1978 Jeep CJ7 4x4 Barn Find!

[TejasCJ7]

Hi Ya'll from the Texas Gulf Coast area.

 

I just acquired a pretty nice 1978 CJ7 Base Model with 9937 original miles on her.. 

 

I have been messing with IH Scouts and 50's Chevy Trucks for quite a while, but sold everything and was not going to get another unitl I heard about this Jeep.  Well, I went to check it out, did not take my trailer, and it really is a 1978 CJ7 with 9937 original miles, so I bought it and then had to go back & get it.  I bought it from the original owner and have all the paper work including the original sales documents from the Jeep Dealer..  They took it to their ranch and it never left. It had been sitting in a barn for the last couple or years, but has virtually no rust and only a couple of dents & dings along with typical brush scratches.  All paint is original and the optional undercoating is mostly still there.. you can see the original factory gray on the frame in spots..

 

The Jeep has the 258 C.I. 6 cyl with the TH400 Transmission & Quadratrac drive with the low range option.  It runs and has no noises coming from the engine..however it will foul the plugs quickly, which I think is vacuum leaks & carb issues.  The tranny does not shift out of low gear, but that hopefully is a pretty easy fix as it may be either not proper vacuum or stuck governer.  

 

I plan to keep it basically original stock, but with some drivability improvements.  First thing is change all fluids front to rear inluding the BW 1339 transfer case with Mopar QT Fluid.  I am going to run 10W30 oil unless someone tells me a better choice??  I also have to buy new seats as the orignals were replaced and the ones in it are WORN OUT!! I will use the Corbeau Moab as I like them and they are reasonably priced.  For now, I am just going to get it running so I can drive it and discover all of her habits, good & bad..

 

Now, for my questions, I purchased the Jeep CJ 72-86 Rebuilders Manual and have been reading it, but I still have a couple of questions.

 

The engine was purchased with the Carter 1 Bbl. carb and I am thinking of upgrading to a 2 Bbl. Weber 38-DGES have questions about the intake manifold.  I really would like to get an original cast iron factory 2 Bbl. manifold if they made them and not use an aftermarket or the newer aluminum one, as I do not want to plumb the water to it.  I think that this engine needs a heated intake to properly atomize the fuel in the end cylinders so am not interested in the Offy or Edelbrock manifolds... I will go with the Weber for overall drivability or possibly use a EFI down the road.  The distributor will be a DUI or CRT HEI and all emission tubing etc will be eliminated as it is not required in Texas before 1984.  I am just going to use it as a run around vehicle on weekends with an occasional trip to the beach.. no rock crawling as we don't have any rocks down here

 

So with all that BS, what suggestions, recommendations or problems do you see??  All comments & suggestions appreciated.. 

 

Thanks for a great manual and a very informative site,

 

TejasCJ7

[Moses Ludel]

WOW, that's a find, TejasCJ7!  Congratulations...Interesting equipment, too.  The low mileage should have everything in good condition, potentially a "new" CJ-7.  The TH400 is bulletproof, as is the 258.  The Quadratrac actually holds up well.  There is a conversion kit (if still available from MileMarker or its successor) for making this TC a part-time unit.  You install front free-wheeling hubs in the process.  That's an option.

 

Glad you have my book, it will cast light.  Thanks for the kudos...An FSM (factory shop manual) or reprint would be valuable as a companion to the Jeep CJ Rebuilder's Manual.  The original Clifford manifold has merit, and a hot water "stove" is available for the desired drivability when the engine is warming.  The later manifolds (1981-90 BBD variety) use a heat stove that operates electrically from beneath the intake manifold.  A consideration.  I agree that you need some provision.  A stock heat stove and weighted exhaust manifold heat riser valve with a bimetallic spring works—as well or better, it's passive, and the bimetallic spring lasts a very long time.

 

As for carburetion, the two-barrel's main advantage is flow.  The intake on an inline six is difficult for balancing cylinder flow volume.  The end cylinders often suffer.  This is why multi-point EFI is an immediate 50 horsepower gain over a stock 4.2L/258.  TBI helps, obviously, when compared to factory carburetors.  Your YF Carter is actually a dependable carburetor, the issue is the one-barrel intake manifold flow.  The biggest gain is port injection, which makes A/F ratios per cylinder essentially uniform with MPI/EFI. 

 

So, is a two barrel better?  Slightly, due to manifold improvements.  The late Jack Clifford assured me over 25 years ago that his manifold was the closest to uniform flow for carburetion.  There's still a gap despite the much improved plenum.  He was referring to his 4-barrel 258 six manifold, which can be adapted down to two-barrel use.

 

The best carburetor, without concerns for emissions compliance (though the tailpipe met every demand), was a stock profile Holley unit for a 266 cubic inch I-H V-8.  I fiddled with every aftermarket approach available in the day.  The Holley was a dead ringer for the tune required of a 258 CI engine.  Nothing else compared, and I used a $10K Horiba A/F ratio meter (on loan from the manufacturer, thanks!) to prove this point.  A simple adapter to the two-barrel '81-'90 manifold, and the rest was simply linkage adaptation and such.  I placed an oxygen sensor fitting in the exhaust and compared performance.  The Holley OE carburetor for this Scout/light truck application prevailed.

 

One limitation with the Holley, which does show up when probing the exhaust at this level, is its sensitivity to altitude.  Rich A/F readings took only 1500-2000 feet above sea level to achieve with stock jetting.  This 2000 feet formula continues.  Does this create an issue?  Not really.  A stock I-H truck could function at 10,000 feet without a jetting change, although the rich mixture's exhaust might be choking and stinging eyes.  OE carburetors are generally more tolerant with regard to drivability.  You'll get there and back.

 

Most go with a Weber.  This is popular and has been around since the 'eighties.  These carburetors are not without their quirks, and fuel pressure requires careful regulation with an inline regulator.  OE fuel pump pressure is enough to unseat the needle and cause flooding.

 

Your distributor idea works.  You'll get a better advance curve and hot, reliable spark.  Service is easy, you eliminate the Motorcraft module, which is always a gain.  The only ignition worse is the Prestolite electronic distributor used by AMC in the mid-'seventies.

 

I like your plans.  If you need rocks, we have plenty.  The Rubicon Trail and Sierra region as a whole has granite.  Nevada offers basaltic (lava) rock.  Take your pick!

 

Have a great time with your "new" Jeep.  Happy to discuss your plans and hear about your adventures.  Share pictures!

 

Moses

[TejasCJ7]

Moses,

 

I have been reading your book and learning as I go..The Jeep is very similiar to the Scouts I have built so should not see many obstacles..

 

I am going to get all the emissions stuff off and all vacuum leaks plugged to start with, switch to the HEI distributor, but keep the 1 Bbl. for the time being..  I am looking at a 2 barrel manifold that will run the Holley 350 CFM 2 Bbl. carb.  down the road.  Right now i just want to get it running decently and don't care about performance increase.  i have other vehicles to fill that need.

 

I need to get the tranny shifting and the steering cleaned up and lubed up..  so that is the next step..  then just work on her as I have time..

 

Thanks for your help,

 

TejasCJ7

[TejasCJ7]

Moses:

 

Started working on the 78 & I may have intake/exhaust problems.  What could I use as a subsitute for what i now have?  Would a later model 2 bbl intake & exhaust work? If so what would be the best one to try to find?  I am not looking for high performance, but if I could use a factory 2 bbl intake & exhaust then i could do the carb and distributor upgrade and call it a day..

 

Thanks

 

TejasCJ7

[Moses Ludel]

TejasCJ7...Without emissions demands, opt for the 266 Scout/I-H light truck V-8 version of the two-barrel Holley 2300 series.  The 350 Holley universal carburetor will never be the right jetting or metering block for your 258.  I'd do an Offenhauser or Clifford intake manifold and a header if you run an electric or manual choke.  A heat tube choke will not work with a header.

 

HEI ignition, ported vacuum directly to the vacuum canister, simple wiring and fuel system.  Use a fuel filter...The stone stock 266 V-8 carburetor (you must verify, I can help with Holley List numbers) is the only Holley to consider.  You'll be especially pleased around sea level, this carburetor will tolerate moderate altitude for limited periods.  Holley carburetors as a whole are sensitive to altitude.

 

A four-barrel choice would be the Rochester Q-jet (genuine item) for a Buick 252 V-6.  Here is another application with similar displacement to your 258 six.  That's the aim for jetting and metering.  There are also small AFB Carter units.  In any case, do not use a carburetor designed for more displacement than your engine.  The universal Holley 350 and 500 in 2300 series would be a poor choice.  Neither is suited for a 258.

 

Later '80s BBDs for a 4.2L are not a good choice, although there are earlier versions of the Carter BBD that will fit a stock 258 two-barrel BBD manifold.  The simpler, non-emissions BBDs were used a lot by Mopar on smaller V-8s in the 'sixties and early 'seventies.

 

My two cents...

 

Moses

[TejasCJ7]

Moses

 

Exactly what I want to do.  Would you please give me the correct carb number.  I searched Holley website and found nothing for the 266, probably discontinued..  

 

I will also look in a IH Shop manual I have.  

 

Thanks a lot,

 

TejasCJ7

[Moses Ludel]

TejasCJ7...I dug out and dusted off my Holley Master Catalog from the day...266 V-8 list numbers for the first/earlier engines would be my preference, they are "pre-emissions" and unconstrained tuning:

 

These are specific application "List" numbers, all are 2300 series 0-1710-6 family carburetors::

 

1) R-1710-1A, -2A and -3A

 

2) R-1710-4A

 

3) R-1710-5AAS

 

There are some later (circa early '70s), mostly Travelall listings for a 2300-C Holley that fits both 266 and 304 V-8s, once again in the 0-1710-6 family:

 

1) R-1710-6AAS

 

2) R-2520-1A, -1AAS

 

3) R-2520-2A, -3A

 

4) R-2520-4A

 

There will be nuances like manual versus automatic choke, but the key to this paradigm is that the circuits in these carburetors, the bodies, metering blocks, power valves, idle circuits, accelerator pump circuits and every other critical part, are engineered for this 266 cubic inch displacement engine that has a similar rpm ceiling to your 258 AMC/Jeep engine (forget 6 versus V-8, carburetors function within vacuum and CFM demands).  Actually not rocket science here.  The tendency is to over-carb an engine. 

 

Note:  In the late 'eighties, I talked at length with Jack Clifford, one of the best authorities on inline sixes in the day.  His formula for selecting a carburetor was one CFM for each cubic inch of engine displacement to run the engine at 4,000 rpm.  If you wanted to spin faster, increase CFM proportionately.  Following Jack's mantra, a 258 spinning at 4,000 rpm only requires a 258 CFM carburetor.  This is why the Carter YF and YFA one-barrel work.

 

The alternative is the 350 or 500 CFM "Universal Holley 2300" circle track carburetor sold as a performance item.  Nothing matches OE engineering for a 258/266 CI displacement application.  I had a box full of metering blocks, power valves, main jets and accelerator pieces, add-ons and OE, and after weeks of horsing around with a 350 (the 500 would work with a 400-plus cubic inch race engine with restricted carburetor rules), I finally accepted that there was no combination of parts that worked.  At the time (1990-91 period), a new replacement 266 V-8 2300 series carburetor was still available and generously furnished by Holley for testing.  The results were an immediate success story.  Lesson learned.  Lesson passed on.

 

The intake manifold, incidentally, was a stock 4.2L/258 late '80s BBD two-barrel AMC/Jeep type, the exhaust manifold was also that period and stock.  I used a 2300 to BBD adapter plate and very carefully centered up throttle valves to prevent risk of binding...

 

Was this a panacea setup?  For a Holley 2300 it certainly was.  I also much preferred the performance over the popular Weber conversion, but then again, I'm an OE restorer and traditional domestic truck fleet mechanic. 

 

As you discover in my books, the real cure remains TBI or, even better yet, a Mopar MPI/EFI conversion.  Even the grassroots 4.0L to 4.2L low-buck MPI conversions offer tremendous gains if you can wade through the wiring and piecemeal mate-up of 1991-2006 MPI components, manifold massaging, an O2 sensor exhaust manifold, wiring harness splicing, an in tank or similar in-line high pressure fuel pump, the PCM and other swap demands required, especially for your '78 engine and chassis.

 

And let's also respect the "barn find" nature of that '78 CJ7.  You may someday want to restore the Jeep to showroom condition!  The Holley 2300 and a couple of manifolds are hardly a challenge.  Hold onto all of the OEM parts you take off.

 

Moses

[TejasCJ7]

Moses

 

Thanks a lot for all of the information.  I am pursuing a CI OEM intake and if I get it , I will do the Holley conversion.  Other than that, I am just going to continue to fix the daily driver items, leaky valve stem seals, plugs, carb kit etc.

 

I agree about keeping it a "Barn Find" and will not make any other mods including keeping the side spare mount..  I just really like the simplicity of this old Jeep and plan to bring everything back to original working condition.. I will not paint it and may not even buff it out too much..  although I think a wet sand by my paint guy would really make her shine.. I have a Spiderweb bikini coming for it and that is all the top that will get put on.  No doors!! And of course new seats that have the original look..

 

Being an old fart myself, I really like the old & original aspect.  I may forgo the 2 bbl. as it does run quite well with the Carter on it..  

 

Thanks again for all your help,

 

TejasCJ7 

[Moses Ludel]

The YF/YFA is a wonderful truck carburetor.  Many have benefitted, and depending upon your driving demands, you could do well to simply "blueprint rebuild" that one-barrel.

 

I'm a restorer, and OEM works well for me...

 

Moses

[TejasCJ7]

Moses

 

Well, I have been busy business wise, but found some time to work on the 78CJ7..  Got the tranny to shift, it was the modulator valve so got that working.  Plugged all AIR holes in exhaust manifold with high pressure steel plugs.  Found out why it was running rich..  choke spring was messed up and it would close as it got hot..  took that apart and fixed it..  lubed the chassis probably the first time in 10 years, changed all fluids except brake, that will come later and adjusted the steering..  got most of the play out, but will need a new steering box..  any recommendations??  or whatever is available??

 

A friend of mine who is like McGyver and a carb wizard (he has a rebuilt Cherokee Chief with a 360 & 727 that he uses as a daily driver and a 49 Willys Jeepster that is completely restored body on a custom S10 Cahssis with the EFI 4.3 GM engine, vintage Air and on and on and on) worked on the carb a little and it runs great.. he said if it gives me any problem, we will just put a rebuild and as you said blueprint the old 1 BBL..  

 

I am a pretty decent shadetree mechanic and worked on my race cars for years and still build parts for oil field equipment, but my friend is a retired master mechanic & machinist..so I pick his brain constantly and he has helped me lots over the years..  Us Geezers gotta stick together to get it done..    

 

I have decided to leave it almost completely stock as it really runs great..   Have a few more things to do: Install the SpiderWeb Sunshade Top to keep the sun off my old head and just drive her and work on it as I have time..

 

I will take some pictures of her with new Antique Plates and running as she should after all these years as soon as I get it off my friends lift..

 

Thanks for your input on "Stock" as I lean in that direction myself..

 

Gene

[Moses Ludel]

Hi, TejasCJ7...If the exhaust manifold ports are away from the cylinder head exhaust ports, plugging is okay.  Never leave air injection tube inserts within the head/exhaust port.  Without air injection pump air flow, these stainless tubes can melt and raise real havoc with the exhaust ports and the exhaust system.  Did any air injection tubes enter the exhaust manifold itself?  Or did the air injection tube manifold fit strictly outboard of the iron manifold?

 

Rebuilding the original carburetor is the best bet, you have correct jetting and staging...As for the steering gear, if it's a manual recirculating ball-and-nut, Borgeson bought the tooling to produce OE style Saginaw gears.  You can buy a new gear for a reasonable cost...If a power unit, also Saginaw, there are many aftermarket suppliers of modified/upgrade gears, and rebuilding the OE unit is most often possible.  I plan to offer a Saginaw (Jeep application, which fits many other vehicle applications as well)  step-by-step rebuild how-to video shortly at the 4WD Mechanix Vimeo On Demand rental library...If enough demand exists, I'll get that done.  Cast your vote here!

 

Moses   

[TejasCJ7]

PO just cut the air tube off and put a small bolt and JB Weld in it.. couple were leaking and all are being replaced with high pressure carbon steel plugs..  The only thing that was in the manifold was the fitting that the air was injected through, Looks like a hollow bolt with a hole in the shaft..  so far all have come out fairly easily.  

 

I am very interested in your Saginaw unit for my Jeep when it is available, I have manual steering which is OK for me.  However if a power upgrade is easy, I might be interested in that.

 

 

Thanks again,

 

Gene

[Moses Ludel]

Gene...As long as there is no tubing extending into the manifold, you're good...The premise is simple:  Without the ambient air from the pump, tubing inside the manifold will get excessively hot and can melt.

 

Power steering conversion is straightforward on your Jeep CJ.  If you can find a donor vehicle with the pump, pump brackets, hoses, the power gear with pitman arm and so forth, make an additional comparison between your steering column, tie-rods, the pitman arm and pitman tie-rod end.  Get all parts needed to complete the conversion.  Any differences between the donor and your vehicle need to be considered. 

 

The manual gear is also rebuildable, in fact, there is generally little wrong with a Saginaw recirculating ball-and-nut gear unless the front end or front wheels took a solid and shocking hit.  Very unusual.  Most issues are adjustments, and there are only two to consider: 1) the worm bearing preload and 2) the over-center mesh load between the sector cross-shaft teeth and the worm nut teeth.  Note that the over-center mesh requires careful consideration for the center position of the steering gear, not the steering wheel position, which could be off center if someone installed the steering wheel improperly.  I have rebuilt and adjusted Saginaw gears by factory methods since the late 'sixties.  The biggest mistake when adjusting the gear over-center mesh preload is that the steering wheel is off-center and used as a guide.  Disconnect the pitman tie-rod end and make certain that the gear is on dead center position during the over-center load adjustment.  Set the preload to factory specs.

 

Worm bearings seldom need attention between rebuilds.  The low mileage on your Jeep would indicate to me that the worm is likely okay (unless damaged), and the over-center mesh needs to be set by the book.  Once done properly, there should be no issue with "wander" caused by a loose steering gear.  You can confirm and isolate gear play by keeping the pitman arm stationary while checking steering wheel play.  (When performing this test, make sure there is no play in the steering column or coupler!)  If there is no play or backlash over-center (check only through the center movement), and if there is wander or indications of loose steering while driving, look to other causes like loose wheel bearings, loose tie-rod ends, loose steering knuckle ball-joints or too little caster angle.

 

Moses

[TejasCJ7]

Moses

 

I would like your input on my cooling system..

 

I got the first part of getting the CJ7 back to being roadworthy and took her out for a jaunt through the countryside today.

 

She ran well, shifted properly and overall for sitting in a barn for a few years did well..  I have removed all of the emissions from the engine and the converter was removed years ago..

 

Today while cruising down the road the temp got over the 195 mark, but would come down if I slowed down.  the Thermostat in the vehicle is old and is 195..  I was wondering if going to a 180 degree thermostat would have any beneficial effect???  Again, all emissions parts have been removed including the EGR valve.

 

I have not gone through the cooling system yet, so it could be as little as a good flush and new hoses etc. but after reading some of your comments on thermostats, i thought I would ask??  which would be the best and remember, I am in South Texas, today was 96 and it is has been up to 109 last earlier this month..  

 

Thanks again for all your help,

 

Gene

[Moses Ludel]

Gene...The concern is keeping the temp as close to thermostat setting as possible, whether using a 195 or a 180 degree F thermostat.  If higher speeds heat the engine up, I would flush the cooling system.  The problem could be the cooling system's inability to properly flow coolant (producing a lower GPH flow than required). 

 

Before spending a dime on replacing parts, thoroughly reverse flush the cooling system.  Make sure anti-freeze/coolant mix is 50/50 for a -34 degrees F safety and cooling level.  Install a new thermostat, 195 is fine if the system is in top shape.

 

This vehicle set up for long periods, there could be block mud and radiator clogging.  Keep in mind, your barn find is now 37 years old.  With the low mileage, this means years of either short drives or parked.  It would be normal to have radiator clogging.  If you feel ambitious, consider removing the radiator and having a shop tank and rod the core.  Flush the whole system first.

 

Moses

[TejasCJ7]

Not really an answer, just an update on the 78 CJ7.

Basically what I have done so far is:

               Removed all Air Pulse lines and hoses.

               Removed EGR Valve

               Rebuilt carb and flipped the choke spring around.. it was in backwards and that is what was causing the plug fouling.. as you gave it more gas it closed the choke more..

               Installed High Pressure Plugs in manifold where Air Pulse tubes were.

               Installed EGR Block Off Plate (billet aluminum) looks funny on the old green engine, but she needed some jewelry..

               Installed Valve Stem Seals

               Pressurized the engine and did a leak down test..  passed with flying colors.

               Installed New Aluminum Radiator, Thermostat (there was none) Hoses , belt etc.

               Flushed the engine and the heater core as well water was run in the engine..

               Fixed pitting on the cylinder head to thermostat housing caused by well water.. (Use Permatex Ultra Gray if you ever need to do this..  put it on both sides with NO gaskets and it will seal completely)

               Replaced Vacuum Modulator with one off of a GM vehicle which got rid of the piping the Jeep used.

               Replaced Transmission Governor..  Old one was pretty good, but since I had a new one I used it..

               Drained and replaced all fluids and filters.

               Installed a SpyderWeb Sun Shade

               Removed tail lights and pigtail back to factory connector and going to install new lights.

               Going to friends body shop after Thanksgiving to have dent by the spare and small one in the hood pulled out.  Then I am going to paint the interior but will leave the original paint on the body..

 As soon as it is painted on the inside, will install new Autometer Jeep Logo gauges.. speedo works except for the temp and the PO already put a temp gauge where the tach goes, so I am just going to put a new one there..

She starts right up and runs like a top..  just need to do a little suspension work but up to 55 or so no problems..

fun to drive..  mainly because it is so simple,,

Gene

[60Bubba]

Sounds like you've got all the critical stuff taken care of.  Here's hoping it makes it another 37 years!

[Moses Ludel]

Lots of work on the barn find CJ, TejasCJ7!...Sounds like you're pleased with the results.

I would like to cast some light on the EGR valve.  EGR is primarily passive and has a minimal impact on performance either way.  Its role is to dilute incoming A/F and reduce NOx.  NOx occurs at high temperatures, and the role of EGR is to lower upper cylinder heat to below 2,500-degrees F.  Otherwise, upper cylinder temps can reach as high as 4,800 degrees F, approaching the heat in familiar metal welding processes (6000-degrees F or so for full liquifying and fusion).

I traditionally have left EGR in place to keep upper cylinders cooler.  Did you notice any improvement in performance from the EGR removal and block-off?  Or did this increase detonation (ping)?  Not sure whether you made all of these engine changes at the same time and can isolate the impact, either positive or negative, of removing the EGR system.

On another note, air injection systems often get tossed.  This can lead to havoc if the air injection tubes still enter the exhaust ports yet no longer offer cooling ambient air flow.  Stainless steel tubes have been known to melt in the exhaust ports when AIR type systems get modified or "gutted" and there is no longer cooling ambient air flowing through the tubes.  The only way to properly remove AIR or air injection is to eliminate the tubes and fit the cylinder heads with suitable plugs.  As for what kind of gains might result, the AIR or injection smog pump draws a whopping 1/4-horsepower or so.  Arguably, and notable on collectible muscle cars, the AIR or pump injection system should simply be restored and left alone.

As for Pulse Air, this is also passive.  It uses existing exhaust pulses to create a low pressure "vacuum" and pumps that air into the catalytic converter to create a more complete burn in the cat.  Power robbing?  Doubtful...We do remove Pulse Air with the installation of a 50-State legal EFI conversion, the emissions drop enough to justify eliminating the Pulse Air system.  Both Mopar and Howell kits allow removal of Pulse Air but not the catalytic converter.  This requires pinching off and welding the end of the Pulse Air inlet tube at the cat.

Moses

Edited November 14, 2015 by Moses Ludel