Q&A: Willys, Jeep CJ and Jeepster Fuel & Spark
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Sent: Thursday, November 29, 2012 1:41 PM
To: 4WD Q & A
Subject: Holley 1920 for Jeep six
Been a while
since we last E-mailed. Hope you had a nice turkey day vacation and are enjoying good
Have completed the A999 installation in my CJ7, and it is
a pleasure to drive. Ceena now tries to monopolize the Jeep!
Have you ever heard about using a Holley 1920 one barrel
carb on a 258 CJ7 as a replacement for the troublesome Carter BBD?
Hi, John…Good to get your note…Glad the CJ is working well with the
999 automatic transmission!
I have an in depth step-by-step at the magazine on setting up a BBD
carburetor. My experience has actually been good with the BBD, especially on engines that require emission
compliance and the range of BBD features (like the Sole-Vac stepper for fuel metering and so forth). They
worked okay when new. We took new CJs and YJ Wrangler 4.2Ls with the BBD onto the Rubicon
Trail...Perfect? No, but they did function. I would attempt a BBD rebuild before opting for a
The Holley 1920 is an okay carburetor dating to the
‘Fifties/’Sixties, and I worked with many of them as a light truck fleet mechanic in the late ‘60s. Ford and
I-H were fond of this carburetor for inline sixes, and my fleet responsibilities included many inline sixes in
surplus Ford, G.M. and I-H truck models.
All Holley carbs are altitude sensitive, and like the 2300 2-barrel
and other end-bowl Holleys, the 1920 has bowl/float quirks that can create real problems on a side-slope. They
require jet changes for as little as 1,500 feet of altitude change—or will otherwise suffer from poor fuel economy
You’re at a variable altitude zone and would be better off with a
swap I did for my Jeep Owner’s Bible: a genuine OEM 2300 series carburetor from a 266 I-H V-8. This
is a rare carburetor but has nearly ideal jetting, plus the right metering block and power valve. Do not
attempt use of a 350 or 500 CFM Holley “universal” 2300 carburetor, they cannot be brought into A/F balance for a
4.2L Jeep inline six!
If you’re curious, I changed the main jet sizing (slightly) in the
I-H 266 V-8 version of the 2300 to compensate for altitude—nothing more than an idle adjustment beyond that…I used
a two-barrel to two-barrel adapter for the BBD intake pattern. It worked nicely, and this application
carburetor actually came in manual and automatic choke varieties…If you have my Jeep Owner’s Bible, note
the comments about this swap.
Otherwise, if you can handle the cost, the Howell EFI system will
provide far more return and driving satisfaction. I recently did a pilot project with the new MSD Atomic
EFI. (See that coverage at the
magazine site for details and ideas on EFI alternatives.) However, that system is
neither emission compliant (no California E.O. as of this date, though we did achieve a Smog Check tailpipe
reading) nor does it currently offer the bolt-on ease of a Howell EFI package. MSD is in the price
range of the Mopar EFI/MPI conversion—which I have promoted for decades…
I have a plate full, or Tierra Del Sol would be fun. I covered
that event in the late ‘80s, when we lived at San Diego County. Almost went last year. It will be a good
way break up your Lamoille winter! I do the Moab Jeep Safari, an industry “must”, and I do look forward to
Moab…On that note, perhaps we could grab a cup of coffee at “Cowboy Joe’s” in Elko when I pass through on the way
to Moab…That’s a definite stop en route!
Keep me posted, John…I always enjoy news from Elko County…Still plan
to get out to your area for recreation and HD video travel footage!
Best at the Holidays,
Carburetor Needle-and-Seat Pressure
Sent: Monday, October 22, 2012 6:08 PM
To: 4WD Mechanix Magazine
Subject: solex carbs on Jeep L/F head motors
instructions and a number of articles i've seen claim a fuel pressure regulator is required when installing a
solex. some mention articles even had pictures of completely installed, ready to run solex carbs, but no regulator
anywhere. most blog and forum writers claim either one is not needed or have tried that dial type regulator but had
it crap out in only a short time. the Holley adjustable is heavy, hard to find a place for, and a bit expensive. so
is a needle-and-seat pressure recommendation for the Solex carburetors, like Weber and any other carburetor. The
best approach with a Weber is to search the aftermarket product listings. I’ve found these in the
As for Solex, the
same rule applies. If the carburetor is an OEM replacement, find the OEM application and note the fuel pump
pressure rating for that engine. If aftermarket, seek the product's recommended pressure range. An
alternative is to try the existing fuel pump pressure and see if the Solex needle-and-seat will tolerate the
pressure. If too much pressure, flooding and fuel enrichment will occur; too little pressure may not unseat
the needle. Typically, vintage Jeep fuel pumps are not high pressure designs.
I have used
pressure regulators with success. You’re right, some are cumbersome and require elaborate plumbing. Check
out Summit Racing’s online catalog, they deal with pressure regulation on a variety of
Keep in mind
that many pressure regulators do not have check valves. This means that they require a steady, consistently
pressurized flow of fuel (like a gear/rotary or vane type pump or a rapid pulsation pump). If a
mechanical, diaphragm fuel pump stroke is slow or has a pause, some regulators will not be able to
sustain a given pressure. In any case, a mechanical pump's check valves must work
Let me know what
50-State Legal Distributor Upgrade for 258/4.2L Jeep Inline
Tuesday, September 04, 2012 9:06 AM
To: 4WD Mechanix Magazine
Have a 1980 jeep with a 258 staight six and would like to upgrade to a HEI distributor. I live in California
and need a CARB compliant distributor. Can you reccomend some?
Rick…MSD’s 8516 Pro-Billet unit is 50-state legal. It does require an MSD 6-series matching digital
click here for details from MSD! A Blaster 2 coil is also
50-state legal and recommended…
Contact MSD for details.
has an HEI for the Jeep 258: http://www.performancedistributors.com/amcdui.htm. Check to make
sure this is 50-state legal, I do not see a CARB E.O. number
this helps…I'm here if you have further questions…
for a 1974 4.2L Inline Six?
Wednesday, April 18, 2012 9:07 AM
To: 4WD Mechanix Magazine
Hello Mr. Ludel,
My name is Bill and I would like some information please. I have a 1974 CJ5 with the original 258-six, T-18 tranny,
Dana 20 tc, Dana 30 and Dana 44 axels and no power steering or brakes.
My question is this: Would the Mopar 4.0L EFI upgrade work for this 1974 block or would the engine itself need to
be upgraded to a newer vintage before the EFI unit would bolt on? The current 1974 engine would be rebuilt at the
same time of course.
Thanks for your time,
From: "4WD Q
To: Bill K.
April 18, 2012 9:19:15 PM
Subject: RE: 1974 EFI upgrade?
goal is sensible. The concern is intake port/manifold matching. I have done this EFI swap on ’81-up
258s, using the Mopar EFI Kit, with great results. However, the HESCO listings say the Mopar EFI Kit will
only fit back to ’76. Why, I’m not clear, since the intake/exhaust ports on 1971-80 AMC 4.2L/258s all use the
same intake/exhaust gasket set. Ignition distributors are the same fit from the 232/258 to the 4.0L.
4.0L sixes use a Hi-Port intake arrangement from 1991-up, yet the Mopar EFI kit is patterned from this engine era
(1994-95 YJ Wrangler, originally). The issue seems to be the exhaust manifold and header choice, in
particular which exhaust manifold will work with the Mopar EFI kit or 4.0L intake manifold.
What you apparently need here is: 1) intake and exhaust manifolds with ports that line up with your 258 head
design, 2) an exhaust header that will be compatible with both your head and the 4.0L MPI intake system, and 3)
cylinder head fittings and ports to accept the necessary accessories in the Mopar EFI kit.
My suggestion would be a call to HESCO’s tech line, phone (205) 251-1472, with these basic questions. Ask why
the 258 is listed back to ’76 and not ’74. (There may be a cylinder head difference.) Ask whether the
kit will fit your engine/head, and if so, what exhaust manifold, manifold stubs and hardware do you need to
complete this installation.
HESCO has a forum, which like others on these topics, is from the lay level and can lead to more confusion than
answers, but here it is:
I would like to know what HESCO shares. Your question and the 4.0L cylinder head swap to the 258 block
question are common. HESCO is a higher level source, they developed the EFI conversion kit with Mopar; if
contacting HESCO does not prove useful, contact me again. I’ll research head castings and engineering changes
between your 1974 engine and the 1976-up 258.
Thursday, April 19, 2012 9:45 AM
To: 4WD Q & A
Subject: Re: 1974 EFI upgrade?
Thank you for
the speedy reply. I'm.... impressed. I'll check with Hesco and see what they say. Clifford Performance has some
interesting approach to upgrading the 258 as well. Although, perhaps in a more traditional way. Haven't really made
up my mind which way to go. But, again, thank you for the response.
Bill, I did not
mention Clifford; however, if you are considering carburetion, they have a lot to offer. Also, MSD introduced
the “Atomic” system at SEMA, and this looks promising—perhaps on a Clifford intake manifold for better intake flow,
and add a header…? Let me know your thoughts and findings. This is all very topical
4.2L EFI Conversion and the 4.0L Inline Six-Cylinder Head
From: John M.
Sent: Friday, July 01, 2011 3:32 PM
To: 4WD Mechanix Magazine
258 head swap
Hello, I am researching
swapping a 4.0 head and EFI onto my 72 CJ 258. Do you have any details of this on your website? I have a '79 CJ that my son and I did a complete restoration in 2008. I
purchased both of your books, and they were
Hi, John...If you have my Jeep CJ Rebuilder's Manual 1972-86, I included details on the Mopar EFI conversion.
The 4.0L cylinder head has extra cooling ports and must be modified to fit a 4.2L/258 cylinder block. Valvetrain
and pushrod design must also be considered, as AMC uses pushrod length to set the lifter clearance on engines
without adjustable rocker arms.
The easier route is to use your 4.2L
cylinder head with either the Mopar Performance conversion or, if you're on a budget and want to pursue it, use
a 4.0L (1991-up) MPI intake and all the factory parts that make up the Mopar EFI conversion. The latter route
(piecing together your own system with OEM parts) requires the aftermarket TDC crankshaft pickup or a 4.0L
flywheel and bellhousing changeover, plus fabricating/mating a wiring harness and several other rabbit holes
that you can go down. On that note, there is not a 4.0L factory bellhousing that resembles your OE
transmission’s face pattern. Advance Adapters does make a conversion bellhousing that has a pickup provision,
but this is still work and extra parts.
When Chrysler/Mopar Performance first
offered the EFI/MPI conversion, it was a TBI system with aftermarket parts. The next and logical step was a
50-State legal MPI system patterned off the 1995 YJ/XJ 4.0L components. The simplicity and virtues of
off-the-shelf parts makes this a very good approach. These kits were followed by a '97-up single fuel line
system, and that kit is also relatively easy to install. All of these pieces work with a 258 cylinder head, as
by good sense, AMC maintained the same manifold-to-head configuration from the 258 to 4.0L transition. You do
have the earlier 258 head, so take the time to confirm the intake/exhaust gasket similarities.
I believe the cost of the conversion
kit is justified by the considerable time saved, the fact that all wiring, the high-pressure fuel pump, the
induction system, air intake and sensors make this a virtual turn-key approach. I'm especially drawn to the OEM
parts and diagnostics capability. The current kit is actually OBII era components. You can get a trouble code
from these PCM units (included, too!), as the supplied wiring harness has that provision. The kit includes the
distributor, coil, injectors, rail and pressure regulator, sensors and other needed items.
For use on a '72 258, you will need to
plumb the exhaust head pipe for an oxygen sensor. This is a non-issue, bungs are available readily, and any
muffler shop can install the threaded bung. (You can, too, if you MIG weld.) Of course, there is time and work
involved in any conversion, but the gains are really worthwhile; there is nothing better than MPI. A TBI
alternative does not provide the uniform fuel distribution per cylinder, which is even more noticeable with an
While the 4.0L head does offer flow and
combustion chamber improvements, a 258 head is more than adequate for normal highway driving and any kind of
trail use. The alternative is a 4.6L stroker engine build, using a 4.0L block and heads, a 258 crankshaft and
the Mopar EFI conversion kit (or combination of recycled parts and some pieces from the Mopar kit). Since you
have already restored the ’72, including the engine presumably, you are probably not in the mood for scrapping
the 258 long block.
One cautionary note: I would keep
compression at 8.5:1 to 8.7:1 maximum for use with the MPI conversion. Otherwise, you will be running 91-octane
fuel to overcome detonation with the leaner, factory-programmed mix and a 258 cylinder head. (This is a footnote
that comes with the ’81-’90 4.2L Mopar EFI conversion kit. Mopar Performance recommends 91-octane fuel and a
195-degree F thermostat for complete combustion at a stoichiometric air/fuel mixture of 14.7:1.) There is minor
room for timing retard/adjustment, done through the PCM. At Denver and in the Rockies, detonation should not be
an issue, as the atmosphere will in essence reduce your compression. 87 to 89-octane could work just fine at
Look at the system in my
Jeep® CJ Rebuilder's Manual...This is Mopar’s ’95
4.0L MPI prototype, the current Mopar Performance kit is similar but with single rail fuel supply…If you have
further questions, I'm available!
John M. comes
From: John M.
Sent: Tuesday, July 05, 2011 10:56 AM
To: 4WD Mechanix Magazine
Subject: Re: Fw: Jeep 258 head swap
Okay—I think you have talked me into the Mopar kit. I am slightly
curious on the 4.0 head swap. I did do a full rebuild on my 258 with about 2500 miles, so everything is
tight. If the 4.0 head would add another step increase in performance/hp/ mileage I would consider though. If
you can elaborate a bit more on that idea, I would appreciate it.
Do you have a recommended source for the MPI kit? I understand I will need a new front damper on my engine—do you
have a part number for this unit?
Thanks—I appreciate your help and response.
Hi, John…The Mopar Performance kit should be available through Mopar
dealers and Jeep dealerships. 4Wheel Drive Hardware and HESCO have been parts suppliers as well.
HESCO did some of the development work.
With your full rebuild and recent cylinder head work, I would not
bother with the labor and parts involved with head swapping. The 2000-up 4.0L head has small valves; previous
4.0L heads offer some gains in combustion chamber design and resistance to detonation as I have shared.
Claims of a "40 horsepower gain" sound extreme, I'd like to see dyne results. Later
smog era 258/4.2L sixes have a 110 horsepower rating stock…That's a 36% increase
in power from a change in combustion chamber and port design. EFI/MPI
port fuel injection is another story. A 50-plus horsepower gain is
I would bring into the equation combustion chamber size. Keep in mind
that the 258/4.2L has a longer stroke and more displacement. This means that if the combustion chamber
for a 4.0L engine is too small, there will be an increase in compression, not a good idea with
regard to detonation. I would compare chamber cc's before plunging into this one in any
While some convert these heads by using the right cooling
port plugs and even a complete 4.0L "head kit" available through various sources, there is a real issue with
oiling the rocker arms. Later 258 and all 4.0L engines oil through the lifters and pushrods.
The 1965-72 AMC 232 or 258 sixes, and the early 1974 engines (not the 1973 engines), have a
pressurized rocker shaft oiling system. The 1973 and late-'74-up engines oil the rocker arms
through the pushrods. You have a 1972 CJ, and if the engine is that origin, the 4.0L head will have no
provision for oiling the rocker arms. This is an issue!
Note: The 258 first appears in 1971 AMC references, using a "type
one" cylinder head with a rocker shaft (above). Back and forth AMC parts availability clouds the head
applications from 1972-74. The distinction is a rocker shaft with cast rocker arms versus canoe-type pedestal
rocker arms (below illustration). 1975-up 232-258-4.0L use the basic design
For the engine speeds involved in normal highway and trail running,
and considering your primary driving venue at Colorado, I see little incentive to change the head. I would
stay with the 4.2L/258 head and concentrate on installing the Mopar EFI kit. Below is one source for the kit
from 4Wheel Drive Hardware. There are kits for automatic and manual transmission, each referenced as
“1981-90” model year but suitable for use back to 1972. Below these listings are the vibration dampers, one
for automatic transmissions, the other manual transmissions. All part numbers are official Mopar Performance
Click here for access to the section on Mopar EFI at 4Wheel Drive
Note the additional mounting kit for the damper when used on a
1972 engine. There is also the Howell TBI system described, an alternative if cost is critical. If
affordable, MPI is superior to TBI.
John comes back...
From: John M.
Sent: Thursday, July 14, 2011 8:24 AM
To: Moses Ludel
Subject: Re: Footnotes from Moses...
Thank you Moses - I did actually purchase a '95 4.0 head that
had a complete valve-job just completed and had not been installed—so is was definitely going that way!
Thanks for the follow up—maybe I should sell the 4.0 head and just go with the original 72 head?
My jeep is a '79 but the engine is a '72 from the casting code "410 A 18" on the side of the block. You are
right—I was a bit mesmerized by the "40 hp gains."
I did order the Mopar MPI kit and should be here next week. I appreciate your thoughts and welcome any others
you may want to share.
John, glad I brought the oiling issue up. You would have
gone down the rabbit hole on that one. So much for anecdotal enthusiasm on the forums, you can wind up
way short of facts.
Although there are gains in the 4.0L head design, we’re talking
about a low-speed engine for all intents. AMC was not that off the mark in 1972, it’s ridiculous to
assume a cylinder head in that era flowed “badly"—realistically, the 258 head was somewhat less
efficient than a 4.0L head; the older heads were prone to detonation due to less efficient
AMC’s aim was quick torque rise and fuel efficiency, always gained
by the highest manifold vacuum at real operating speeds. Frankly, for me and others familiar with the
4.2L, the bore/stroke of the 4.0L was a great disappointment in terms of tip-in performance and speeds
under 2,600 rpm. The 4.2L reaches its peak torque by 1,600-2,000 rpm (depending upon year and
tune). This rivals a 5.9L Cummins diesel’s torque rise and peak at 1,600 rpm!
The weak link of all inline carbureted sixes with a centrally
located one- or two-barrel carburetor is the induction system. I had many discussions with the late Jack
Clifford (Clifford Performance) on this very topic. His ram induction manifold for the 4.2L claimed major
horsepower gains through more uniform distribution of fuel/air volume to individual cylinders. You’re way
beyond this with the pending electronically managed fuel-and-spark system: MPI for the most part
eliminates any differences in A/F or volume per cylinder!
For off-roading, the performance you want is bottom end, quick
torque rise and a nice ceiling in the 4,200-4,500 rpm range, each characteristic of the 258 bore/stroke
and cylinder head design. If I were doing a stroker motor (4.6L or 4.7L) with the oversized 4.0L
bore size and 4.2L stroke, I would use the 4.0L cylinder head.
I have always run a late tubular OE exhaust manifold with these
Mopar EFI conversions. Either the stock stainless OE or a Borla makes the best sense. There are
gains in performance here, as the OEM iron manifolds are a hindrance. Make sure port shape and
gaskets match up to your cylinder head.
Won’t it be nice to concentrate on the induction and exhaust
installation and not have to remove that bulky cylinder head in the chassis? You’ll be very pleased with
the outcome here, and I predict 87-89 octane will work without detonation at your altitude and manifold
Keep me posted. I trust you’ll get a sensible deal on the
Mopar MPI/EFI kit and be happy with how much product it contains. You might save the 4.0L head for when
you build a 4.0L block into a stroker with your 258 crankshaft—200,000 miles from now. Have a good time
Keeping the Vintage
CJ's 196 Rambler Six
Sent: Monday, March 28, 2011 6:37 PM
To: 4WD Q & A
Subject: Re: '64 CJ5
The engine has a flat, machined pad on the front of the driver's side just
below the head. It has the code 801 C06. As near as I can guess the motor is a mid sixties, iron, OHV
The carburetor is a Carter. There is an aluminum tag that is folded and beat-up. The
first number is hard to see. The tag could say either 3706S with an E7 underneath that, or it could
say 5706S E7.
Once again, thank you for your help.
The carburetor is a 1964 build, the last 196 two-barrel
type. Carter model is a WCD 3706S. The design continues into the 199/232 era. It incorporates two (separate)
floats and requires some time on the bench to set up properly. The carburetor probably needs rebuilding, with
care, and you don’t want to get an “exchange” carburetor when you have such an original
I recommend a “blueprint” rebuild of this carburetor to
alleviate the flooding on hills. A carburetor kit should still be available. You would order it as 1964 Rambler
196 2-barrel under the tag number 3706S. There are aftermarket carburetor options, but this carburetor is jetted
and engineered precisely for this engine application—if it is rebuildable, you have a way to go here. To offset
your flooding and starvation issues, I would set floats at precisely the height recommended in specifications,
just high enough for adequate fuel supply.
If you would like to quickly confirm your problem, try
adjusting the float heights to specification. A thorough rebuild would rule out clogged passageways and other
restrictions. I have rebuild steps and specifications if you need them. I can scan and PDF a copy your
A New CJ-7 Owner Seeks Carburetor
A. Sent: Saturday, January 15,
2011 4:27 PM
To: 4WD Mechanix Magazine
I recently bought my first CJ, and I am very
excited. It is a 82 CJ7 Renegade, a project that ran when I purchased it, but the 232 that
a previous owner swapped into it did need to be rebuilt. I would like to
build a daily driver Jeep that I can drive in every season. In Iowa, we have the coldest winters and the hottest summers. We get tons of snow and deal with icy
roads. Luckily The CJ7 does have a hard top, and I am looking for hard doors. I am looking to build a modest utilitarian Jeep. I will need it to travel 60 miles round
trip to work on the interstate yet be able to hit the mud and trails. My
concerns are the icy roads and winters. I am not concerned with my driving. I know when to go slow and when to stay
home. Hitting a patch of ice with possibly the wrong tires or too much
height of a lift that would increase my center of gravity is what scares me. I am
looking for recommendations in tires and lift
height. Currently, I have a 2.5" BDS suspension lift kit, taller
shackles, and no sway bar. I'm not sure how much longer than stock the shackles are but,
it does fit 33 x 12.5 x 15" M/T tires without any rubbing. We
have a great small town local tire shop that advises me to keep the width of my tire contact down for good traction in Iowa driving conditions. I have been thinking
about replacing the shackles with heavy duty stock ride height, changing my tires to 31 x 10.5 x 15" BFG all terrain tires, and installing a sway bar with
sway bar disconnect links.
Here are a few
more specs on my Jeep:
Currently rebuilding 232 (I tried to find a 258
locally with no luck) 2140
Holley 2V conversion
Dana 300 transfer case
Frame is in great shape (not sure how it survived in the
Midwest!) Tub has some rust but very
Painless Wiring harness (to be installed)
I would appreciate your advice on my tire and
ride height selection. I would also appreciate any other advice. I hope I have given you all of
the information you need. I
really enjoy reading your Jeep Owner's
Bible and CJ
Jeep Restoration Manual. Both of the books have been a great source of
information. Your website also has some great information. Thank you
for posting the videos of the Wounded Vet Ride. As a veteran, I really appreciate what you and
the organizers are doing for vets. I hope one day that my family and
Jeep could join you on one of the rides.
Thank you for
your time...Chad A. at Independence, IA
Reply from Moses
Hi, Chad...Thanks for the comments on my
books and your enthusiasm for the magazine's content! You have acquired a great Jeep. It can meet each of
the needs you describe, especially with a hardtop and doors. If you need
hard doors, consider placing a "wanted" ad at the magazine's free private party classified ads. The ads get wide circulation...
I appreciate your attention to
center-of-gravity, which I emphasize in my books. For an '82 CJ, I would limit any lift to a maximum of
4-inches. Running 33" tires (traditionally 33x12.50x15), I would use
8-inch or even 10-inch wide wheels with shallow backspacing to increase the track width. If you're not after maximum lift, 31-inch tires (traditionally 31x10.50x15) on 8-inch rims
would work with a 2-inch suspension lift. In my view, any lift should be
chassis/spring and not a body lift. Use quality shock absorbers. Your current 2.5" suspension lift is okay for the
31-inch diameter tires. 31x10.5x15 tires with a multi-purpose tread would
work here. Wheels should have shallow backspacing to widen the track width and offset the
If 31" tires will do, I would install a
shackle reverse kit at the front springs and do as you suggest: bring the lift down to 2-inches or so. The front
sway bar is always an asset on the highway, causing the vehicle to squat
on turns, reducing body roll and lowering its C.G. on corners. The question is really whether
you need the 33" tires or not...At 2.5" true lift, you might be able to
fit 32" tires. Your local tire store's advice is sound: the narrower tires do
have more pounds-per-square inch of vehicle weight on the contact
patch. This provides less "flotation" and works better on slick, icy highways. Another aid for icy
asphalt is a tire design with extensive sipes. Years ago, I tested
the Goodyear GSA tread with its multi-purpose design and considerable sipe count.
They worked great, even to 33" diameter...By contrast, the
last thing you want is a wide-spaced cleat or "high-flotation" tire on icy pavement! High
flotation tires work best for mud and sand.
Since your concern is family safety, I
would emphasize that the distinct difference between your CJ and a longer wheelbase vehicle is handling in
an evasive maneuver. You can offset C.G. issues with a track width
increase, and should do so. The sway bars help on the highway with cornering. You do not mention whether the Jeep has manual or power steering. Power has a quicker ratio and reacts
promptly. Manual steering is slower and does not create as much risk of
over-steer in an evasive maneuver. Get used to driving a shorter wheelbase vehicle, know how it handles and
reacts. As a rule, steering input should be thoughtful and precise,
not jerky if avoidable.
I have the advantage of an 81-inch
wheelbase CJ in my earliest driving experience. To this day, even at
higher speeds in the desert, I have a sixth sense for the twitchy reactions of a short wheelbase, higher C.G.
chassis...You can learn this, too, Chad.
The 232 is actually okay if you keep
overall vehicle weight in check. It should deliver good fuel efficiency. I'm envisioning a likely original
axle gearing of 3.73:1. You have an overdrive with the T-5 and a slight
overdriving effect from 31" tires—even more effect with 33" tires. This should make
fuel efficiency decent if the
Holley carburetor has correct jetting. Since you're at a constant
altitude, you can jet that carburetor accurately for your Iowa driving
If you're currently committed to the Holley
2140 carburetor, I'm curious what the original application was. This is a most unusual carburetor choice,
a carburetor best known from vintage V-8s. Often called the "Christmas
Tree" design, the first 2140 I worked with fit a Mercury V-8 from the early '50s. Most
Holley carburetors are altitude sensitive and require re-jetting to
perform well at higher altitudes. An alternative might be a Quadrajet (Rochester)
non-feedback carburetor from a smaller displacement G.M. engine. If
built properly, with a brass float upgrade, a non-feedback Quadrajet will deliver excellent fuel efficiency on the small primary bores and maximum performance on the large
secondaries. Despite the wide range of opinions about the Quadrajet, in "blueprint" form, this is one of the best carburetors available and far less
sensitive to altitude changes.
If you want to stay with
the 2V configuration, a Motorcraft 2V (2100-2150 series), used on engines
like the Ford 302 or 304 AMC V-8s, is also a great carburetor. (Similar
Autolite carburetors were fitted to 221/260 Ford V-8s and other smaller applications.) Be sure to use a smaller bore 2100 carburetor! Making an adaptation to your intake manifold would be a consideration.
I trust this
helps, and your questions are welcome, Chad. Ask more when necessary.
Reply from reader Chad
Sent: Sunday, January
16, 2011 5:00 PM
To: 4WD Q & A
Subject: RE: Iowa CJ7
Thank you for your advice, it really helps, and
I appreciate it. You were correct to think the 2140 was a strange combination. I purchased a new
2300 and adaptor plate that are still in the box. The intake I am
using is a stock '82 258 intake with the coolant passages and electric intake
heater. For our cold winters, I thought it would be good to keep the
I chose the 2300 because our local parts stores
have an extensive Holley section. I wanted to be able to stop anywhere for parts. I thought about
the Motorcraft 2100 and found a local junkyard with plenty of rebuildable
cores. What I didn't like about the Motorcraft was our local parts stores could not support it as well as the Holley. The stores can order anything that I need but are very
limited on what is on hand. I do like Motorcraft 2Vs and I have
experience rebuilding them. I am up for reconsideration if you think the Motorcraft would make a better carb. I am
more of a Ford/Mercury guy, but I do appreciate the Qjet. A close
friend of mine in the service taught me that a Qjet performs excellent if treated properly.
Is there an adapter I can use for the stock
intake? I am up for any carb options. I still have the stock BBD. I really wish my budget could
afford the Mopar EFI.
Thank you again
for your time...Chad
Reply from Moses
Chad...In ranking order, the Mopar EFI
would be the number one choice (costliest, too, I know). The BBD can be rebuilt as I describe in the '72-'86
CJ Rebuilder's Manual and also in an article that I have posted at
this website: click here for BBD rebuilding details. The BBD
can be a success story if done right—despite the bad press. In your case, however, the OEM peripheral
feedback devices are likely gone. A feedback type BBD carburetor should be considered only if the whole regalia of factory ignition and fuel system equipment is in
The 2100 series Motorcraft is
an excellent choice, trouble-free and easy to
rebuild. An off-the-shelf 2300 "universal" carburetor is, in my view, a poor choice. I have two
universal 2300s in my stack of old parts, one a 350 CFM, the other a 500
CFM. Using all of the tuning parts available from Holley and a borrowed $10K Horiba portable (real time) A/F
meter, I could not get either carburetor to tune right for a 258 Jeep
six. (In off the shelf tune, either version would over-fuel a 232 and fuel-wash your freshly
I did find a Holley solution, however. In
researching OEM Holley carburetors, I found the part numbers for OEM 2300 series carburetor versions used on the
266 I-H Scout V-8 (late '60s era). I located a correct, original
carburetor for a 266 engine and rebuilt it by the book. That carburetor, by its design,
was still hyper-sensitive to altitude, but at your elevation, the
Scout (or I-H pickup) 266 V-8 carburetor might work—at least for a 258
For your 232
six, a clear OEM application would be the 2300 carburetor used on the Jeep Tornado OHC sixes of the 1963-65 period.
These engines were 230 cubic inches, even closer to the 232 in displacement. Here is the Holley model and "List
Number" for that application:
Model 2415—with automatic choke, the Holley List Number is an
R-2934A. This is a 2300-C style carburetor.
sake, I believe you would be better off with a 2100 Motorcraft from a smaller displacement, popular engine application like the 304
AMC V-8 or a Ford 302 V-8...Another possibility is a 2G or 2GC Rochester two-barrel designed for a Buick 225 or 231 V-6. Any of these carburetor
choices require a matching air cleaner with the right base size. Carburetor linkage must match or be configured
My overall approach for your application:
Find an OEM carburetor that originally fit an engine close in cubic inch displacement to your 232 six. (A 260
Ford V-8 Autolite 2-V, for example, might work well.) The idea is to use
the OEM engineering and provide the right fuel metering and jetting for a
displacement. Trying to attain this with a universal "high performance" carburetor is virtually
impossible. On the 2300 universal carburetor, I changed the metering block, power valve, main jets, float block and pump lever, and still did not reach the right flow for a 258 cubic inch six! (The 2300 universal carburetors must be for
circle track racing or patterned for a large displacement truck V-8.)
Carburetors designed for engines closest in
displacement to your
Jeep's 232 cubic inches will work best. This is ultimately about flow rate (CFM)
and proper fuel metering (tuned jetting, power valve flow, metering passage sizes, etc.). Pick your favorite carburetor design!
California based 1982 CJ-7 has a high performance V-8 transplant and fuel injection. For
video details of this Jeep, click
provides an update:
To: 4WD Mechanix Magazine
Thank you for
posting my door ad. I decided to return the 2300 Holley and universal
base plate and go with the 2100 Motorcraft. I found a gentleman off
Ebay (Michael Erhmann) who sells 2100s for Jeep applications. The carb will
be built for my application: 232, Iowa's altitude, daily driving with occasional off-road use, and manual
The carb comes
with a machined adapter plate to go from the 2V BBD base to the 2100. I like that better than the universal. I was afraid
I would be chasing vacuum leaks. I also bought a short ram air intake
from him. I like the looks of the air intake; I attached a photo for
My next item I
have to research is the ignition system. Along with rebuilding the
232, I will be replacing the wiring harness. The original was a mess
w/burned wires and bad splices. I appreciate the Duraspark ignition,
but I have been toying with the idea of an HEI for simplicity. There are pros and cons to each, and I do not know what is the better application for a
Jeep. I am also a fan of MSD ignitions. This may be another
budget restraint. Thank you again for all of your
Reply from Moses
You're welcome, Chad! Nice looking induction system...If set up for your 232 cubic inch
engine, a 2100 will work well. Manual choke is a
Hardware has a bargain basement price on an HEI retrofit distributor. It has the advantage of G.M. replacement parts and the coil-in-cap...That's the best deal
price-wise. See my PDF article (http://www.4wdmechanix.com/pdf-downloads/Jeep%20Ignition%20Upgrades%20for%20Pre-EFI.pdf) for details on ignition system
options...MSD is tops but expensive when you need the "box", too. DUI makes a quality G.M. HEI based
distributor. See my article...Also, in my Jeep Owner's
Bible, I share the use of a Chrysler "5-pin" module with the
Jeep/Motorcraft type distributor. This makes the OEM Jeep distributor more reliable. Jacobs recommended this
CJ-7 and a Quick Discourse on Closed Crankcase
Ventilation and EGR Valves!
From: Chad A.
Sent: Saturday, March 19, 2011 11:20 PM
To: Moses Ludel
Subject: RE: Fuel System Questions
Thank you for the words of wisdom. I will be using the
charcoal canister and along with it, the EGR system. I have a few parts to
order but, it
looks like I will be able to find everything. As far as the
EGR, do you
think it would be all right to run the hose straight from the CTO
valve to the EGR? The schematic you sent (thank you) shows the hose running from the CTO valve, to an EGR TVS
on the air cleaner, then to the EGR. I want to run the new
intake system I ordered and it won’t have the TVS.
I also have a canister question for you. Once I cleaned all of
the caked mud out of my canister I found the external filter deteriorated and I lost a small amount of
charcoal. I believe there may have also been some sort of a cloth screen inside the canister to keep
the charcoal from spilling out. Is there supposed to be
a screen inside or does the external filter keep everything in place?
Now that I am learning how my emission system works, I am
regretting ordering the MC 2100 with a manual choke and open vented fuel bowls. I am starting to wish I
had ordered the carb with the electric choke and the correct fuel bowls that I could connect to the charcoal
Unfortunately, the carb I have was built to my request and for my
application. It doesn’t feel right to ask Mike to allow me to return the carb so he can build me
another. I may ask and offer a restocking fee but I am going to have to think about
it. Any advice, do you think I would be better off with a more emissions friendly
carb? I hate to put you in the middle of my moral dilemma but, I really respect and appreciate
your advice. You have been a great asset and I cannot thank you enough.
Reply from Moses on the value of an EGR
Hi, Chad...Great idea to run the EGR. This will keep upper
cylinders of the engine cooler and preserve your fresh rebuild. Many disconnect the EGR as a "smog" part, but
the EGR serves a quality function, especially in reducing risk of detonation on low octane fuels. (Cylinder
temps can reach 4,800 degrees F without EGR; EGR drops temps to 2,500 or less degrees F for defeating NOx.
The EGR gets its signal from manifold vacuum routed through a
coolant temperature switch. The goal is to keep the
EGR off-line until the engine warms to a certain temp (usually 140-degrees F or so, sometimes hotter) before
the EGR will open under vacuum. The CTO and TVS switches accomplish this. Check the vacuum circuit
again. The EGR uses CTO (coolant temp) and its own EGR TVS (thermal vacuum switch). As long as you
have a sufficient vacuum signal at the right temps, the EGR will function well.
TAC is a separate function. If you
choose to eliminate TAC (thermal air cleaner) due to an aftermarket air filter, you can route the EGR as
described, using CTO and the EGR/TVS if necessary. CTO routes vacuum via a thermo coupler valve in the
cooling system. The thermal coupler is typically a wax pellet valve that melts wax as the temp rises. As the
wax melts, the switch opens vacuum ports. By itself, a thermal coupler can operate an EGR. The TVS may be an
additional safeguard that AMC built into the system, or it may regulate or stabilize the vacuum signal. Using
a simple vacuum gauge and blipping the throttle as the engine coolant temp rises will indicate the vacuum
available to the EGR. You can test EGR opening with a hand vacuum pump. Yes, you can keep it simple and
clean, as long as there is an adequate vacuum signal to the EGR at the right
EGR should not open at an engine
idle or when the engine is cold. Make sure you draw the vacuum signal from the correct vacuum supply port.
Typically, this is a "ported vacuum" source at the carburetor that will not provide a strong enough vacuum
signal at engine idle to open the EGR. (If you hook to manifold vacuum, the signal will be high at an idle
and open the EGR, which should not occur.) Ported vacuum is typically used for distributor spark advance
As for the EVAP canister, these are
usually not serviceable. They get replaced as a unit. Years ago, cleaning the canister was possible and part
of emission service. Unless you can compare your canister with one in good condition, it's hard to say
whether all material is in place. There are no workshop measures described; however, I copied a 1981 Mopar
parts section that shows a filter available as a separate part. (See attached PDF.) The filter is shown, no
other parts are removable.
Regarding manual choke, bowl vents and non-vented air cleaner,
there are emission era engines with manual choke like the Toyota Landcruiser F and 2F
engines. A vented 2100 fuel bowl will hardly cause global warming, there are far larger
contributors, and, yes, we should be concerned about the environment. There are some minor
advantages of not having a vent port on an off-road vehicle, but again, the CJs with Buick V-6s had vented
bowls and sloshed around plenty without a lot of grief. If it's a hassle to return the carburetor, allow
yourself the minor fume venting from the float bowls. Most states do not require gas pump nozzles with
capture and return vapor systems, and a single fill-up of gasoline will vent more fumes to atmosphere than
your 2100 carburetor will in a whole day of hard off-roading. Typically, the vent is only open with the
throttle closed to idle speed, and this is necessary...Later 2100 and 2150 carburetors do not vent their
bowls to atmosphere, but that would require a carburetor change, too...Use the manual choke appropriately,
and you can control cold engine fuel mixtures wisely.
[Beige text is the reply from Moses
From: Chad A.
Sent: Sunday, March 20, 2011 8:59 AM
To: Moses Ludel
Subject: RE: Fuel System Questions
Thank you again for all of your insight. I have attached a vacuum
diagram that I found for a Howell TBI that I think may work for my application.
The only line not shown is the inlet hole at the rear of the valve
That inlet hole at the rear of the valve cover should be the crankcase
return to the air cleaner that enters inside the air filter element.
I will install an enclosed filtered breather and route
it to a port on my air cleaner or a through port on the Motorcraft 2100's air filter base. I hope this
will cover all of my bases.
You’ve got it…A PCV valve creates low pressure (vacuum) at one end of
the valve cover and draws through the crankcase. The breather hose from the air cleaner to the rear of the
valve cover will provide the air supply for the crankcase. This makes for a closed system.
As far as the carb, I think I may keep what I have. The carb vents are
inside the air filter so hopefully some of the gasses will get drawn back in and get burnt. I also like the
fact that the carb came with a manual choke and throttle
If the vents are inside the air
filter, you have it made. Risk of fumes escaping through the air filter is minimal, and as you say, the fumes,
if any, get drawn into the intake stream with the engine running. Note that Howell’s diagram shows
manifold-sourced (not ported) vacuum to the middle pipe of the EVAP canister and the PCV valve. The CTO and
distributor source is ported vacuum (very low at idle, increasing dramatically just as the throttle opens,
tapering off as the throttle opens wide). Use this approach for your system.
Hopefully I have this section of my build covered. Next project; the front diff. I
knew I had a bad rear pinion bearing out but upon further investigation, I found the inner pinion
bear bad and a diff case half way full of dirt. Looks like a total rebuild and a new learning
I honestly can't wait.
In my Jeep CJ Rebuilder’s Manual 1972-86, you will find a low
pinion Dana 30 axle build step-by-step. Follow it for best results. At the website, I also cover the
high-pinion 30 with an ARB Air Locker; many of the fundamentals are the same. The book also covers your Dana
300 transfer case and the rear axle (AMC Model 20)…There is a lot of detail in that book—tailored to your
Next Step: Chad's Carburetor Leads to EVAP
From: Chad A.
Sent: Thursday, March 17, 2011 10:10 PM
To: Moses Ludel
Subject: Fuel System Questions
The weather is starting to warm up in Iowa so I am back out
garage trying to wrap up my 232
rebuild. I am happy to report that
the long block is complete and going to start installing the
intake and fitting my rebuilt Motorcraft 2100. Moving to this phase of the build has brought new questions that I am having a hard time finding the
correct answers to. My
questions have more to do with the fuel system. The
fuel tank has more ports coming out of it than I have ever
seen. From the sender I have a fuel outlet and
return. At the driver’s side of the
tank I have two ports for fuel vapor
I plan to use both fuel outlet and return with my Motorcraft
carb and the stock Jeep fuel filter. Is there any reason that I should not,
I have read where folks have only used the outlet and plugged the
For vapor release, I have the two ports coming out of the fuel
connecting to the liquid check valve then to the rollover
check valve. From there, a line runs to the engine bay to the charcoal
canister. I am missing everything after the canister. The pieces I do have
look rough, and it looks like I will have to repair or replace what I have
and find what I am missing. From my initial research, this may not be
an easy task.
I am debating removing a portion or all of the fuel vapor
release system even though I know it is not the right environmental decision.
If I removed the canister and kept the rollover protection, I am
concerned where to release the vapors. I am thinking about running a
hose then filter above the rollover check valve but I am concerned with
collecting gas vapors. I have also read about folks plugging the vapor
lines at the tank and running a vented fuel cap. One forum stated that a
vented fuel cap might suck in water during a water crossing. If I went the
vented fuel cap route, I am concerned with fuel spillage in the event of a
I don't have the off-road experience to answer my questions
and I would really appreciate your advice.
Thank you for all of your help.
Reply from Moses Ludel:
Hi, Chad, happy to assist!
Glad your project is progressing...
Always use the three pipe fuel pump with a return line. The return line keeps fuel circulating
through the fuel pump and helps resist vapor lock. Using a two-pipe pump or plugging the return will defeat this
function. Although an emission-era addition, the three-pipe return pump is an
Folks screw up these systems constantly, thinking that stripping off and
plugging components will simplify the approach. EVAP is a closed system, which is safer and more environmentally
friendly. It is also passive and does not tax power or performance in any way—when hooked up
properly. I have attached a scan of the typical ‘80s CJ EVAP vacuum hose
circuit for your benefit. It should be self-explanatory and helpful for restoring your
here to download a PDF copy of a typical '80s era CJ 258 Jeep
Restore this EVAP system to
function properly and as intended. Even though some of the emission devices will likely not be restored in
your case, you can at least make the EVAP functional—and safe!