Ok I donÆt mean to be a smart a$$ with this response, but what does your repair manual say? I would imagine it would have a length for your engine? I honestly don't know though. But thinking about it logically, all of your intakes should be the same length, and all of the exhausts should be the same length, all 12 could be the same length too. I wouldnÆt take too much work to pull them all out and lay them up side by side in order to see if there are visual differences.

bought the longer 9.72 pushrods (mine measured about 9.5). replaced the one on the bad valve. the valve now opens and doesnt backfire. still some slack on that rocker however.

You might take that rocker off and look at the ball.. It may have extreem wear for aome reason.. Perhaps a prior valve job has led to more wear in that area.
Rockers with balls can be purchased individually.. Might be a good idea..
The longer pushrods are what I install in used heads. Even with a new camshaft I use them and have never had a problem.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

unfortunately nobody stocks rockers and rocker balls around here, so i have nothing to compare mine to. just looking at them id say they are good.

new variable: i tore the valve cover gasket. went to get a new one. the one for an 86' doesnt fit. had to buy the one for a 1980. does this mean i have an 80' head or entire engine? how can i tell?

as for the smart a$$ comment (kidding). my manual says 9.64 to 9.66; parts store says 9.72; jeep dealer says 9.695. mine measure about 9.5. i was just looking for a solid figure for reference.

Once you understand the workings of the hydrolic lifter you will understand why there are so many slightly different rods available.. The lifter "swells" to meet the length of the lifter. It operates there untill the wear gets to the limit of the "swell' available. When this limit is reached the thing starts clicking.. telling you to put in a longer pushrod...or do something to make the lifter work as designed again. If they are not clicking I cannot see how a slightly longer lifter would make it run better..
As for the cover gasket...NOBODY knows which head was installed in a particular year!!! period!!! About 1986 there were at least 2 different shaped cover gaskets. The one with the long straight side was the one that finally won out. It came with a plastic cover, not steel or aluminum.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

it is clicking. when i run the engine with the valve cover off i can see that the clicking is coming from my problem valve. normal wear seems out of the question considering i replaced the pushrod with one almost a quarter of an inch longer and still have play. im thinking that the lifter has a broken spring inside. but anyway the jeep is now running as good as it did before so im satisfied. i ordered two rockers and a bridge today. maybe i can get rid of the slack with those.

while im getting top notch advice ill ask another question: my jeep has never idled well. i can retard the timing a bit and solve the problem, but i lose a lot of power. ive had a friend who is good with carburators rebuild and adjust mine but it doesnt change a thing. any tips?

I think I remember you saying it is an 86.. If so it has a computer that retards the timing. It should also have a serious lectric module on the back of the carb.. the computer controls that too. Set the timing as indicated in the specs and it should run as goood as it can without modifications.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

What Bigbird79 said is exactly what I fixed for someone
recently, doubled gasket, one stuck to the block.
A collapsed lifter is his problem, I'm sure they are
not solid.

im glad to say the jeep is back in dependable status once again. when i first started on it i failed to check the pvc valve. i just pulled the line off and made sure it had suction. yesterday it dawned on me so i checked the valve. the guts were gone. i replaced it and she purrs like a kitten now. as for the oil pressure problem, solved it to. i removed the pump and disassembled it. there were some fragments in the pressure release valve (i want to believe from the pvc valve). i cleaned it and now the pressure tops out at 70 when cold, 40 warm idle, 60 on the road.

i replace the rocker balls and put the longer pushrod on the bad cylinder and it eliminated the slack. i still think its possible the lifter is collapsed, but im going to run it for the time being.

thanks for all the help guys