'87 GW engine rebuild options

[orange65]

Evening All, I'm finally at the point where I need to make the decision to rebuild the engine in my 87 GW. Two plus years ago I fell down the rabbit hole trying to fix a coolant leak. While my initial forray was successful, there was some collateral damage. I broke several exhaust manifold bolts off in the left bank cylinder head. I became a little overwhelmed with the thought of potentially removing the engine to properly rectify my situation. And then life got in the way. Flash forward... I am ready to move ahead with repairs, So any and all advice is greatly appreciated.
I am considering just having the heads and intake rehabed at a machine shop, then reassembling. Planned on new push rods and lifters. Option two is to replace the heads and intake with new parts ie; aluminum maybe better perfomance parts. I had a strong running engine before I parked it. How much of a risk am I taking by not rebuilding the bottom end as well? I'm at 200,000 on the odometer. Aside from the machining, I am able to do the work myself.
Again, I thank you in advance for help.

[tgreese]

Mmm. A seasoned engine is a reliable engine.

While your engine is together, I strongly suggest you evaluate it for wear. The primary tests are a compression test, wet and dry, and oil pressure. Suggest you get a mechanical oil pressure gauge and measure the hot idle oil pressure, hot as in full operating temperature. Post up your results for comment.

The most common catastrophic failure for these engines is low hot idle oil pressure leading to a failed rod bearing. Sometimes you can patch up a low oil pressure problem; I strongly suggest you measure before you assume anything.

Your local automotive machine shop can make quick work of the broken exhaust bolts. Take the head off, take to shop, reinstall with new gaskets.

Also, new lifters and pushrods won't do much for you, unless you want to replace the cam. If you have a lifter tick, you can remove individual lifters and do a leakdown test. Lifter noise is tied in with your oil pressure; again, you need to measure.

hth!

[orange65]

Appreciate your quick response and sage advice. Unfortunately, it looks like in my first post, I neglected to include the fact that had already removed the intake manifold and the left bank cylinder head. As far as diagnostics, when the engine was operating, I did do a compression test and found each cylinder to be between 130 and 140psi. Oil pressure gauge always showed between 40 and 60. Don't recall hearing any lifter noises.
If I decide to have the engine overhauled, are there any key questions you would ask someone who might take on the rebuild? I have no experience in rebuilding an engine, but consider myself to be handy enough to take on the project. I have done a lot of research and do have quite an assortment of automotive tools, but realize that I will need an engine hoist and stand to facilitate this project. I have done some research regarding replacement parts. Are there suppliers that you might recommend?
Thanks for your help.

[tgreese]

Overhaul and rebuild are different. Why have you assumed you need either? From your above posts, I don't see a reason for either. Usually worn rings or bad valves will show wide variability in compression readings. Uniform readings is a good sign.

An old-fashioned overhaul suggests rod bearings, rings and valve job. Seems like shops today would not do an "overhaul," instead doing a "rebuild" with a remanufactured block and heads. This has less liability for the shop and more profit. The block and heads typically are "remanufactured" in a factory setting from disassembled parts.

If it were mine, I'd fix the bolts and put it back together. Kinda think you'd be throwing away the remaining half of your engine's life by rebuilding. A worn-out engine typically burns oil, has compression that's low and variable cylinder-to-cylinder (like 100-50-130-140 etc), and has low idle oil pressure.

To me, engine rebuilding is a fun and satisfying job. However, it expects a lot from you, the rebuilder. Tom Monroe's book is good https://www.amazon.com/Engine-Builders- ... 1557882452 and I would suggest you study it from cover to cover if you want to rebuild your engine. Suspect this is dated now, and now you'd be hard-pressed to justify a piecewise rebuild over a factory-built reman. Maybe if you want something special, or just want the experience and satisfaction of building the engine yourself. Analyze costs and confidence in your efforts.

[letank]

X2 on Tim's idea.
I have 229k in the 85, does not burn oil, 1q per 2200 miles, pass Cal smog test with good numbers. Start easily, all I really did was the valve seal job... and rust control. Of course, the usual, alternator, starter and waterpump swaps apply.

[orange65]

Thanks for the continued input. When I had it running, I had no issues with performance. I just thought that at 200000 miles, If i had it partially apart, wouldn't be a good time time get some work done. But, If you're telling me that it should not be a problem to put it all back together, I'm all for it. Probably a good idea if I take the heads to the machine shop?
This decision has weighed on me for awhile. You guys have really lifted my spirits. I should have posted a year ago. I have ordered the book that was recommended. I'll keep you up to date on my progress. Thanks again.

[tgreese]

I would not do the heads by themselves unless there was a burnt valve. That would show up on the compression test. And you'd have a misfire.

[Srdayflyer]

if you are thinking about changing the lifters, check the lifter face that rides the cam, if it is dished time to consider the lifters and cam as it is recommended to change both at the same time, as far as the heads go , i would consider changing the valve seals,check the head mating surface with a good straight edge to check that the head isnt warped , straight edge and head should show no space between the 2, a good way to check the timing chain for wear is to turn the crank in direction till you feel the engine beging to turn over, stop, reverse direction of rotation but pay attention to the distance the ratchet handle moves till resistance is felt that dimension of ratchet (play) will give you a good idea of chain stretch(wear) i consider changing mine when they 1/4-3/8 inch. AMC blocks had a higher Nickel content to preclude wear as quickly say as compared to a chevy block plain cast iron with a low nickel content