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i'm looking at an engine for sale with a 1967 657 block and trying to determine if it's been apart before. the stamp pad info (300hp MT) is still intact so it likely hasn't been decked but i'm wondering if there's anything else that would indicate it hasn't been rebuilt short of disassembly.
fwiw, if this motor has been apart it looks like it was a long time ago.
A 657 is somewhat desirable as they were used as 302 (Z28), 350 SS Camaro and some Corvette blocks however MT IS NOT a Corvette suffix for a 1967 300 h.p. engine. BTW, it does have the desirable draft tube hole.
If we're talking about a fully assembled engine, at least a long block, I'd say that VegasVette is right, the best way to determine if 'anything' has been done, you'll need to have it apart. But, along with looking at the stamped pad up front that you already checked out, there is another telltale to look for that might indicate that the engine has been apart before. When these engines were fresh off the showroom floor, the engines typically had 'thin' steel shim head gaskets. When they were rebuilt, the tendency was to use composition head gaskets. I bought my 65 300 horse Coupe back in '85 and while the rest of the car was trashed, the engine gave up some good compression test numbers and I spotted something that made me think it had been rebuilt. The composition gasket just peaks out at the lower/front corner where the head hits the block and if you spot it, good chance someone has been there. Check out the pic, the composition gasket is just to the right of the Power Steering Cap.
Mike T - Prescott AZ
A 657 is somewhat desirable as they were used as 302 (Z28), 350 SS Camaro and some Corvette blocks however MT IS NOT a Corvette suffix for a 1967 300 h.p. engine. BTW, it does have the desirable draft tube hole.
sorry i wasn't clear, "MT" was meant to indicate manual transmission. i'd really like to use this block for just the reasons you mentioned. the seller thinks it hasn't been apart but doesn't know for sure. he says that if on tear down it's more than .030 over he'll refund my money. however, if that's the case it means i'll have to likely go to .060. i'd rather not have to do that.
" When these engines were fresh off the showroom floor, the engines typically had 'thin' steel shim head gaskets."
vet65te, great idea, i'll check it out.
to do a tear down i have to commit to buying at .030 over or less and i'd like to avoid that.
I would say a commitment to buying at .030 or less is reasonable. And as far as you're concerned you should want to know for certain it's no larger than .030. You could remove the pan and measure the piston skirts sticking down delow the cylinder to confirm. But you also need to know it's no cracked.
The gasket info is correct. I take a feeler gage. Should be no more than about 0.018” between the deck and head for shim gasket.
If the .018" steel shim gasket is still there you can be pretty well assured that the heads have not been off. This OE gasket was never available through service parts. The service gasket was thicker (.026" I think) because it was assumed that if the heads came off for valve work they would be surfaced up to ten thou.
Also, I'm not aware that the aftermarket ever supplied a .018" shim gasket. Measure with feeler gages at the front or rear of the head-block interface. Also, I think the OE .018" gasket has a small round hole that you should be able to see in the corners of the gasket where it protrudes beyond the head.
Years ago when I was in engine rebuilding TRW performance pistons were only available in std, 030, and 060 for most Chevrolet engines. I just checked and now they have the L2166NF available in .040 and I would think KB would also have them in .040.
To the OP, do you have a borescope? If so, pull a plug or two and send the probe down into the cylinder and if the piston tops aren't too carboned up, maybe you can see if there is a number stamped on the piston indicating it was overbored.
I've had my 65 300 horse Coupe since '85 and it needed just about everything rebuilt or replaced but the engine, luckily, ran well and had good compression numbers so in all this time, I had never torn it down other than in the beginning when I reinstalled the
original cast iron intake and rams horn exhaust manifolds. About a year ago, I was curious as to what the cylinders/pistons looked like even though I had already seen those composition gaskets peeking out from the corner of the heads so broke out my borescope and
looked inside and was surprised to see domed pistons in there but also saw the .030 stamped on the piston top. See pic.
Mike T - Prescott AZ
Bored Before?
