Strange 292 head problem

Gene F said:
I guess I am asking if a person has a 312, that was shipped out of the factory as a 292 and the heads were put back on it, what compression is that upgraded 292 likely to be? I feel like the 312's that left the factory that way are superior to a 292 that has been punched out. I keep telling people yes they are a 312 CID, but they are not the same engine that you think they are when you refer to a "Thunderbird 312".
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IF a person took a 292 and built it into a 312, it is a 312 (CI).

IF a person did the same and claimed the engine was numbers correct for a particular classic car - /and/or dedicated restoration or possible survivor -, then it would be fraud (IMO) (unless very careful about CASTING and DATE CODES) (maybe)(and was not declared to be the original engine).

CR/HP would be determined by parts chosen and modified. The year of the engine would determine how much you could get away with (say 1957 assembly as compared to 1956).

To find true CR, one would have to CC the heads and cylinders. Even the use of different style head gaskets would affect final CR.

Does that help?
 
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miker98038 said:
I wouldn’t worry much about slight compression variations even from one bank to another. It won’t be a problem on a stock or mildly modified street engine. I would be more concerned about things being “square” as I stated above.
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I would worry as if I took the heads to a machine shop and either they failed to notice/check the actual cause of the malady, you are out of a lot of money.

If just a sight difference between the banks, it may not be noticeable but a large difference will (rough idle/spark plug readings). How well does an engine run with one or two dead/near dead cylinders?

Whatever one's interpretation may be, it was good Yankee money spent for the incorrect outcome. Now will the shop stand behind it's work?

Would I assemble the engine with that head? No way (especially a customer's car). Grind down head bolts and pray she sits down correctly? You are just begging for it.
 
It's a good idea to involve the shop that did the heads before you do anything to them. They might fail to accept responsibility and blame it on you.
 
I went back and reread this, and all I found is the machine shop “reworked” the heads. I guess that could mean a lot of things, from hot tanked and lapped to milled, guide’s, guides cut for keeper clearance, etc. I could go on. So that’s a business problem to me. Did you get what you paid for? Still a problem.

I’m still more concerned (I don’t know the term) that everything is in spec -straight and true-flat-fits properly.
 
^^Yes, it is enough to piss you off.^^

I'd never put it together that way and hope that it's okay. You will ALWAYS be thinking "is it going to hold?"

When I was into VW's in the 70's, I had all my heads done by a local shop. I took four pair of heads to be done, they did a great job. My mistake was taking a pair of 1200cc dual port heads to be redone. I paid for the job, but had no use for the heads. I ate the cost and never used them. Just the cost of doing business.

If the machine shop can't/won't fix the problem, I'd be looking for another head.
 
KULTULZ said:
Case in point, recently watched a U2 short about a guy with a 396 CHEVELLE (and you respected these damn things back in the day). Somewhere he had lost his take-off heads and was wanting to bring the car back to numbers correct. Finally found a set (CASTING ID correct and DATE CODES within a few days of one another) on FleaPay and when he got them ($$$) they were pure junk.
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Here is the video -

- https://www.youtube.com/watch?v=1RJ78O8KrA4
 
I was a senior in HS in 1973 and owned a 1969 SS396/w 375-horse L78 (same engine rated 425 in 65) and L88 427 cam. Needless to say, breaking the tires loose was easier done than said. I didn't keep it long, however, because I couldn't afford $10 per day for gas. My folks didn't appreciate the raw-gas smell in the garage.
 
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