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1979 Jeep CJ7 Engine Needs Help


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#1 MountainHound

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Posted 20 July 2014 - 11:45 AM

I have hit a sticking point with my engine upgrade on my 1979 Jeep CJ-7. After 8 years on running a carb I finally fuel injected my CJ.
 
I installed a Hesco MPFI kit and Genright tank with an in-tank YJ module. My old tank was rusted and after installing the tank and new lines the fuel pressure was and still is good. The rest of the install went well and I did all the work myself.  I also purchased a new '83 exhaust manifold with the O2 bung. I could not find a good replacement valve cover for that year 79' and the old steel one leaked a lo so to continue the build  I purchased a 4.0 head, exhaust, and valve cover which solved the leaky valve cover issue and a few other clearance issues. I also believed this to be an upgrade after the research I had done.

 

After installing the 4.0 head the problem I faced then was not getting the right pre-load with the pushrods.  I reused my 4.2 push rods, rockers and bought new bridges. After encountering this issue I stopped on the build for a while. Watched the video on getting right valve clearance, pre load etc... and bought an adjustable push rod.
 
Well then I got deployed and the Jeep sat. I think my next mistake when I got home was to fire it up. When I started it The valve train was noisy and I believe I have a bad lifter on No. 1 exhaust. I changed the oil to find shiny metal and the Jeep idles rough and low rpm. I think this was due to the incorrect pre-load coupled with the Jeep sitting, and me turning the key.
 
So with that said I am at a cross roads with where to go from here. I have contacted a few rebuild shops to diagnose my issues and fix my pushrod problem. They say the short block may be toast and I should look at a reman. I am looking towards that too. Only one shop will actually look at it but it is in another city. 
 
The CJ has a manual T-18A with a 1980 scout dana 300. Which year 258 would mate to my drivetrain? I still have the exhaust for an '83, intake, accessories etc.. so I am thinking an '83 reman. I would like to have an aluminum valve cover as well.
 
Advice?



#2 Kevin's 83-CJ8

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Posted 20 July 2014 - 05:49 PM

MountainHound,

 

Just from reading your post, it is obvious that that you are way more capable of a mechanic than I will ever be. So please take my reply with a grain of salt. I cannot advise you about lifters, preload or lifter stuff…I am not comfortable with any of that.

 

But I have an 83 and I just changed out the motor. I went with a crate motor and have been happy with it.

 

It took ½ the time to install than it would to have if I tried to fix the motor and the cost was about the same. They paid for the return shipping and with the core refund, it was not as expensive as I though it would be. I was expecting about $1,800 but I think after the core it was like $1,200. It only took a weekend to install. If I would have known how low the end bill was going to be and how much work it was going to save me, I would not have messed around with trying to fix it in the first place. I would have gone straight for the crate motor and been done with it.

 

Since I put it in, it has been trouble free and I am glad I did it. You sound like a really good mechanic so you are probably capable of handling pretty difficult repairs, but it is going to take time and money. If I were in your shoes, I would go with the crate motor and be done with it.

 

I am just starting to do my own repairs and work, so do not put to much weight on what I say. But for what it is worth, I hope it helps.

 

Kevin



#3 MountainHound

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Posted 20 July 2014 - 06:13 PM

Thanks for the advice Kevin,

 

If I have a good manual I can get things figured out....but swaps are a bit tough for me. Fixing up an old Jeep teaches you a lot. Good luck on your repairs. I think if I can get the right motor to mate with my T-18 figured out I will go with a reman. I do like the fuel injected 258 a lot.  I use the Jeep mainly light to moderate crawling and isn't a daily driver. The fuel injection helps with the long trips though. I won't go back to a carb at this altitude. Not looking for a v8 or expensive stroker build. 

 

Need to fill in my profile. May help with my post

 

Thanks again



#4 Moses Ludel

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Posted 29 July 2014 - 03:01 AM

MountainHound...I read your metal in pan comments, likely camshaft/lift shredding (shiny steel) unless the material looks like bearing Babbitt (copper and alloy).  In any case, the engine needs to come apart.  The 4.0L head conversion requires specific needs like plugging off unused cooling port holes and such.  You likely know all of that.  My video/vlog at the magazine covers the Jeep inline six valve clearance issue and does explain the overall lifter clearance needs.  The head, head gasket and block milling can each change the lifter clearance, as you note.  You were on the right track here, MountainHound. 

 

If it makes sense and you have access to a leakdown tester, I would run a leakdown test on the existing engine.  Sounds like the camshaft lost the #1 exhaust lobe.  If the valves are actually sealing with each piston at TDC on its firing stroke, you can get a rough idea of the lower engine condition.  Then again, given the metal findings, you might as well tear the engine down and do the inspection—or use this as a core for a rebuilt short or long block.  You've changed the head, and some shops will not accept a "mixed" core, engine block assembly from one era, head from another era or engine design.  In your case, the 4.0L head does have value and so does the original 4.2L head core.

 

When you get the 4.0L head modifications right, many like this combustion chamber improvement, so rebuilding your engine could include the 4.0L head.  As for what year engine to get, any 1981-90 4.2L core will do.  They are plentiful out there.  The mate-up to your existing 1979 bellhousing and shim plate, flywheel, T18A and the Scout Dana 300 should all work out, pay attention to the crankshaft/flywheel stick-out distance from the block on your replacement engine.  Make sure the flange is at the same stick-out position as your '79.  Also use the correct pilot bearing in the crankshaft to align the T18A input shaft properly.  If all this currently works with the '79 block and crankshaft, you should be able to duplicate that with the later core.  If you decide to rebuild your '79 engine, that's fine, too!

 

The valve cover issue goes away with the 1987-90 YJ Wrangler application.  It uses an aluminum valve cover similar to a 4.0L.  There is also the time-honored use of an earlier head, like your '79 type or up through 1986, with an aftermarket Clifford or Offenhauser aluminum valve cover:  Not as many bolt holes but still a major improvement!

 

Glad you'll stick with the Mopar EFI, there is really no better system.  You've done all the legwork already, and the system is in place and working.  Good job!

 

Moses 



#5 MountainHound

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Posted 29 July 2014 - 06:45 PM

Thanks Moses!

 

I took the 4.0 head back off yesterday. I pulled the lifters out and they all look pretty good. The one I believed to be sticking isn't dished or showing any unusual wear and the rest look surprisingly good. Doesn't mean they are though but will reuse them.  I also looked at my push rods, rocker arms and pivots. Push rods are fine. Five rocker arms and pivots are worn to where I cannot see the oil channels anymore. Checked the oil again to make sure nothing big and shiny was in there. I didn't see anything this time but I am sure it's in there somewhere ha ha.

 

I have decided to try to make the 79' head work for now at least until I can get the reman. So a few replacement rockers and pivots and a couple of gaskets and I'll see what happens. I will hold onto the head, valve cover and header for now. My buddy has a Cj and may want to give the swap a go.

 

 

Thank you for the advice on this. I will do some more research before purchasing the later model engine.

 

I have read there are two different timing chain covers so I will pay special attention to crankshaft stick out and the pilot bushing.  My current setup works so at least I have something to go off of. I would be bummed if I got it all together and had clearance issues and would hate for the pulleys not to line up.

 

I will update my progress and let you know how it goes....It would be nice to keep the 79' going for a while but I may be kidding myself 

 

Josh



#6 Moses Ludel

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Posted 30 July 2014 - 05:34 AM

Hi, Josh (MountainHound)...A heads up on lifters:  If you did not lay them out in order of their positions on the camshaft, get a new set of lifters.  The lifters establish a wear-in pattern that can cause havoc if you mix up the fit between lifters and lobes.   Also, with the lifters out, look over the camshaft lobes carefully.  See if there is a lobe going away.  I'm still looking for that shiny metal that showed up in the crankcase!

 

Of course, shiny metal can be other things, like the mechanical fuel pump arm or lobe on the camshaft (which you no longer use with your EFI conversion, install a block-off plate at the fuel pump location if you haven't already done so); the distributor drive gear; the rocker arm metal that you know went somewhere (good prospect here!); or timing chain and sprocket wear.

 

The rocker arms are a good possibility if the camshaft and lifters are not the culprit.  Check closer here, Josh.

 

If you're curious about timing chain wear, I have a quick check that has served me for over 45 years:  Pull the distributor cap.  Turn the crankshaft (head removed, this is safe and easy) in the normal direction of rotation until the TDC mark just comes up on the crank pulley.  Stop at the TDC mark.  Note the rotor position.  Slowly turn the crankshaft in the opposite direction (backward from normal rotation).  Note how far the crank pulley moves before the rotor begins to move.  This is the amount of timing chain wear!  Allow for the mesh movement between the distributor drive gear and camshaft, the rest is actual play at the timing chain...On a pulley the diameter of a 4.0L EFI conversion kit's pulley, up to 5/8"-3/4" movement at the surface of the pulley would still be tolerable.  Beyond that, the chain and sprockets likely need help!

 

Moses



#7 MountainHound

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Posted 09 August 2014 - 06:43 PM

I put on the old 79' head. I replaced the rocker arms, pivots and bridges. I put the lifters in the same locations one at a time and they looked fine. The cam also looked fine. The rockers and pivots did not. I changed the oil and filter and there wasn't any shiny metal this time. I believe the metal was from the rockers. 

 

After putting the old head back on I have no noise from the valve train or lifters. I believe the problem was the 4.0 conversion head and the push rod length and pre load. 

 

I checked the timing from your advice and the chain is within spec. What a good way to check! The distributor driven gear is also good. wear pattern is good.

 

So I need to get a new exhaust going to do a good road test. All the tests I did were at idle in the street with only a down pipe with no cat or muffler...my neighbors are really cool haha.

 

I talked with clifford on the valve cover. I had to grind the flange around the bottom and file to make it fit. No leaks yet. I am hoping it works for a while This valve cover is 3'' higher than stock so it interferes with the throttle cable and the thermostat. I got a spacer from hesco for the thermostat and the throttle cable moves ok but still doesn't look like it will ride that way for too long. 

 

I have taken a couple of pictures that I will upload and update after I have the exhaust in place and do a true test drive. 

 

Thanks again!!



#8 Moses Ludel

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Posted 10 August 2014 - 05:08 AM

MountainHound...Every day of reliable transportation and four-wheeling is money saved and expenses postponed.  Count the "free" miles!

 

You did the right thing here, if the '79 engine and cylinder head will behave itself and prove predictable and reliable, what the heck, right?  The 4.0L head conversion and pushrod relationship sound like the issue.  Rocker arms are plentiful and not expensive (new or used).  Confirm your pushrod clearances, and go for it!

 

The later crankshaft stick out and pilot bushing/bearing comment is about the rear or flywheel end.  This simply needs to be checked for a match.  The front snout is not an issue, a shorter snout can be used with your Mopar EFI pulley by simply installing the longer bolt and special washer (available from HESCO) for this crankshaft conversion.  There is nothing intrinsically wrong with your 1979 258, you're past the intake and exhaust manifold issue with the EFI conversion as long as the intake and exhaust ports lined up okay.  The Mopar EFI conversion intake manifold is supposed to work with a 258 port arrangement. 

 

Beyond that, if you want to take the guesswork out of the engine, run a leak down test once you know the lifter clearances are correct.  We can discuss the results.  (You'll find leakdown test pointers at my forum topic post: http://forums.4wdmec...+leakdown +test.)  As for metal sweeping through the engine, that's not a good thing, but a string of oil and filter changes could remedy the situation.

 

Keep us posted!

 

Moses




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