compression test results
#4
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Join Date: Oct 2002
Location: Ohio
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Car: 1985 Iroc-z
Engine: 355 sbc
Transmission: 700r4
as long as the number from all cynlinders are in the same ballpark, probably mosty likely could very well be no if ans buts about it = good..
#6
i think im leaning towards rebuilding this engine. since the compression is good, is it likely i wont need to bore it and get new pistons and rings? maybe just refreshen it with new bearings and gaskets? i know i need to take the motor apart to find out for sure but not ever having done this before its hard for me to know what to look for. i just want a fresh bottom end that will go for several thousand miles more. with what i'll learn from doing this, i will know a lil better what to look for when the time comes to disassemble the 91 motor with the knock.
#7
You could have a bore worn as much as .005-.007" oversized (or even more on the bottom end of stroke) and still be sealing well. Only measurement of the bore will reveal the wear, taper, and roundness of the bores. However, at least there is apparently no significant failure of the rings, lands, valve sealing, and cylinder walls. You may still need replacement pistons and boring, but you may not either. As a general rule, I think it's always a good idea to at least break the glaze of the bors and install new rings, even it they are stock bore.
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#8
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the engine i'm working on now was the cleanest best looking engine i've ever taken apart. the pistons still looked new, it had .008 taper/out of round and needed bored. you just never know untill you get inside and look and take soem measurements. the 4.3 i rebuilt in my truck a few years ago was the nastiest engien i ever had apart. black sludge every where. piston had a flame cut notch in down it and after 95,000 miles the bore was good and i didn't have to have it bored, just a new set of pistons.
#9
ok so basically the first step would be to have the block thoroughly checked once i have all the parts out of it. also im gonna talk about this rebuild with the machine shop that did my heads. thanks for the help.
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