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post #1 of 4 Old 06-09-2007, 10:12 PM Thread Starter
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1987 YJ Wrangler 
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Engine rebuild tips

Hi all...
I'm rebuilding my '87 4.2 and would love to read about some of the tips you experienced people have. I already have the block, head, manifolds, pistons, crankshaft, etc. back from the machine shop and ready to assemble. The reason for the rebuild started as a leaking rear main and a oil pan that refused to come off. I'm glad I decided to rebuild as I found 2 cracked pistons, worn timing gears, and peeling cam bearings. I'm not new to rebuilding engines... it's just been awhile and I know that there could be some new things I can learn.

One question I have... the Haynes manual says to put the crank in first. Unfortunately that doesn't leave a lot of room for installing the cam. Can I install the cam first?

Anyway, any tips you guys have would be appreciated. I've been down for 6 months due to a job loss and would really like to get this thing back together.


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post #2 of 4 Old 06-10-2007, 01:03 PM
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You should be able to install the cam first. Every rebuild i've done I have always put the cam in first reguardless.

I would say a good tip is to keep each valve/lifter/spring/retaining clip/rocker arm together from where they came off. So, the intake set of those on cylinder one would stay together, the exhaust set on cylinder two would stay together, etc if you'r not replacing any of those since they have a specific wear pattern. But since its already disassembled, oh well. And you should at least be replacing the springs anyway .

Tip two would be if you can do a 3-angle valve job and re-grind the valve seats. If you dont have the tools/knowhow, see if you can find someone to do it. The valve job alone will make a noticable difference in the engine and where its not life or death important, it sure helps. Gives the valves a much better seal.

Aside from that...go slow, don't brake anything, don't cut corners, and be sure you put the piston rings in right!
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post #3 of 4 Old 06-10-2007, 02:46 PM Thread Starter
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Thanks for the reply. I had a machine shop do the head/valves for me, as well as hone the block, put the con rods on the new pistons, polish the crank... all the things a good machine shop does. As for the rockers, I can see the wear marks that differentiate the intake set form the exhaust set, so I'll be able to match those up.
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post #4 of 4 Old 06-10-2007, 03:30 PM
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Rockers and pushrods are cheap, I replaced those also when I built my stroker.
Read the links provided about premature cam wear, some people have had their cam die in as little as 3000 miles.

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