Thread: 327 rebuild

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btw, the head gasket I hav miked at .052. how far will it crush when the head is torqued down?

They're generally sold stating "compressed thickness" on the package. I would think that the amount of crush is going to vary based on composition, but don't go by my thoughts on this one....

As Roger stated - gaskets are typically sold with their compressed thickness listed on the packaging. .052 is a thick gasket - stock SBC is typically .041.

In my opinion, in a rebuild situation, the head gasket should be selected after the piston to deck clearance has been determined. Ideally the quench should be in the .039 to .045 range. For example, if you have your block decked and squared and the pistons measure .010 from the deck at top dead center and you used a .030 gasket you would be at .040" quench, which in my opinion is near perfect if you’ve built everything else correctly.

I just found some 14014416 heads off a 305. they're 58cc according to chevy casting #'s url. I calculate 10.86 compr ratio if I use a gasket that crushes to .043 and a .010"' deck clearance. the vales r 1.84 intake. am I headed for trouble with pump gas?

IMO yep. You might get away with 10.86 and premium ethanol blend with aluminum heads, but I'd say iron heads are going to be detonating if you push the timing.

is it possible to adjust the timing to prevent detonation. if so, how much do I "lose" by way of performance?

No, you cannot adjust yourself out of a bad choice. Forget those heads.

Originally Posted by ecreek

I just found some 14014416 heads off a 305. they're 58cc according to chevy casting #'s url. I calculate 10.86 compr ratio if I use a gasket that crushes to .043 and a .010"' deck clearance. the vales r 1.84 intake. am I headed for trouble with pump gas?

I don't understand why you're being so hard-headed about this static compression ratio thing. Max 9.5 for iron heads. Max 10.5 for aluminum heads. Each point only allows the motor to make 4% more power, so taking a 300 horsepower 9:1 motor to 10:1 will make an additional 12 horsepower. That's it. That's the awful truth. Keep your street motor at 9.5 or less for pump gas and iron heads.

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its what I have available. and I wanted valves larger than 1.72. ide reaaly like 68-70cc chambers with 1.84 intakes (to accommodate the edelbrock manifold and 4V carb). that gets me in the low to mid range 9's CR. ide setl for any % increase in HP if it doesn't lead to detonation. do u know of any cast irons that fit this bill?

Stop! Save your money. Then buy a set of new Vortec heads and intake. It's better to wait and do it right the first time. It costs a lot more to do it wrong and have to fix it again later.

You want budget friendly? Here: Chevy SBC 350 190cc 64cc Straight Complete Aluminum Cylinder Heads 600 Lift | eBay They are not AFR's but better than fooling with old iron heads and they will work with the intake you have,stick a duplicate of the L79 cam in it and claim 365 HP.

I can find an 4V intake easy enough but don't know which head casting #'s I should be looking at. n e thots on this?

The reason you're finding old, "high performance" iron heads so easy is that very few people want them any more unless they're building some period perfect, numbers matching car. Several guys have pointed out that you're going to spend as much or more buying a set of old iron heads and then having them done right than you'd spend on a new set - go back and read Mike's Post #6 again and think about what he's saying. Now the guys selling will be telling you just the opposite, how much better their old double hump heads are than the new stuff, but that's bogus. I wouldn't invest the money in an old, unknown set of iron heads but it's your money.

Originally Posted by rspears

The reason you're finding old, "high performance" iron heads so easy is that very few people want them any more unless they're building some period perfect, numbers matching car. Several guys have pointed out that you're going to spend as much or more buying a set of old iron heads and then having them done right than you'd spend on a new set - go back and read Mike's Post #6 again and think about what he's saying. Now the guys selling will be telling you just the opposite, how much better their old double hump heads are than the new stuff, but that's bogus. I wouldn't invest the money in an old, unknown set of iron heads but it's your money.

Ain't it the truth, Roger? Those old cast iron production heads are only good for ballast. The technology that was used to produce them is 40-50 years old.

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no, I meant vortec head casting #'s are what I don't kno what to look for. I found the vortec intakes for carbueration easily enuf but don't kno which vortec heads to buy for my old 327. will they all fit? or should I b looking for a certain casting # (#'s) suitable for what I need (pump gas) without getting too much compression. a casting # or 3 would help me head in the right direction (no pun intended).