I just picked up a used set of 305 torquer heads for 450.00 they are in great shape and will just be a bolt on come the spring. These heads are 58cc chambers and 170 cc runners 1.94 valves and should work great on my 307 . My 307 has 600 edlebrock carb,performer intake,Crane 266 energizer cam and headers with 2.25 exhaust I was wondering what the compression ratio would be using stock 039" gaskets and flat top pistons i'm guessing close to 10 to 1 .I was also wondering if anybody ever used these heads on a 350 how much horsepower do you think they would support, down the road i'll be looking to up grade to a 350
thanx

Has the engine been rebuilt? Or does it have original pistons still?

By the way, the factory didn't use .039 gaskets. I tore apart an untouched 307 last year and I found a steel shim gasket, not a composite. Stock pistons still in place.

If you've got stock or good hyperneutic/forged replacements...

You'd be right around 9.25:1 with the .039" gasket.

If you used the smallest of the composites, .028" you'd get around 9.5:1

If you're working with cast "rebuilder type" pistons, your CR will be much lower with any composite gasket.

I don't see why your 307 shouldn't make in the 300hp range with those heads. When I bought my 68 it still had the stock motor in it. With bolt-ons it was making in the 250-260hp range(enough to run high 14s). You have better heads (world products claim a 30hp gain) and a cam in yours, so 300 seems reasonable. If you got carried away and added compression, head work and a "big" cam you could make over 350hp with your motor (but a 350 would make it easier).

I picked up a set of World SR used 2 months ago. They were used also with 1.94 & 1.50 valves. One thing I had checked out was seals (none) and flatness (not) so they are getting redone. You might want to have yours checked as well. The seals are a must have and getting it checked now saves time and money.

check on the deck height of that block. If its not zero decked or at least pretty close to it(Id say a .010 deck at most), dont use a .039 gasket. It will provide too much quench distance and that aint good. Factory small block chevy deck height is .025. Even if its bone stock, Id be surprised if it actually measured right on .025, but theoretically, it should be there. Assuming it is at .025, use a .015 to .020 thick head gasket in order to reach a quench of about .040-.045. Thats where you want to be. If the decking process hasnt been done, or hasnt been done recently, the deck surface could have some imperfections. If thats the case, use a steel shim gasket with a copper spray coating and that will keep the thin gasket from blowing if its mated to an imperfect deck surface. If its a zero deck block, the .039 gakset is fine(which will give you .039 quench).

I know the engine was rebuilt because when we had it out of the car to change the cam my mechanic pulled the oil pan and he said it had been bored but we did't look at the pistons that closely to see if they were cast or forged we'll have a good look when the old heads come off. i'll get him to check the deck height but i'm sure it has not been decked , and will dicuss getting the quench down to the .040 to .045 range. My mechanic has removed the springs and valves and seals already to fully check every things and they are in excellent condition.I was also thinking the 307 should be making 300hp now , not great but should be alot of fun .Anybody else run the 305 torquer heads on a 283 or 307 -what compression ratio did you end up with

The compression ratio is going to be directly linked to how far the pistons are down the bore and the thickness of the gasket (these two dimensions added together are called the "quench" area.)

Assuming the block is bore .030 over, and the pistons are common flat top pistons(about 5cc):

.035 quench = 10.0:1 (keep in mind, this is a dangerously tight quench)

.039 quench = 9.89:1

.041 quench = 9.84:1

.045 quench = 9.73:1

After this point, you're beyond the "performance quench distance" of an SBC.

.050 = 9.60:1
.060 = 9.34:1
.070 = 9.11:1
.080 = 8.89:1

The same range of quenches except with a common dished piston (say 12cc) would be about 9.2:1CR at the tightest quench (.035") and 8.25:1 at the widest quench area (.080" for discussion, although many engines are rebuilt with even wider quenches.)

10.13 CR. if you are at .030" overbore and have stock flat-tops using Fel-pro's PN 1094, .015" thick rubber coated, steel shim headgasket. (10.01 CR. if you are still at 3.875" bore?)...

pdq67

PS., down in the hole = .025", 58 cc heads and -4 cc valve notch, flat-top pistons. (I used the "ROSS Racing Pistons" site's compression ratio calculator)..