I have some finned aluminum heads that are 10.5:1. By my rudimentary, and likely wrong calculations, with two head gaskets they might be in usable range for pump gas. Would it work or would it mess up the turbulence?
You might want to recheck your calculations and/or have the heads cc'd again. My recollection is that you couldn't get that high of compression without restricting the flow to a degree that it would be counterproductive (and thus you probably don't really have 10.5:1). How about posting the raw numbers (combustion chamber volume/engine displacement) you are using to calculate the compression? Charlie Stephens
I would't worry about turbulence. If they are that high (which I would doubt) it's pretty much all you can do to get the CR down. But even if it ends up high, just add water!!
I believe you will only wind up opening the proverbial "can of worms"? How are you figuring the C.R. Put up some add'l engine specs, along with some brands. No way would I "double-up" on the gaskets! Chances are you may not that be that high?? Thanks, Gary in N.Y. P.S. You will definitely have to "cc" the chambers to be more accurate though still.
I'd guess the valves would hit the head with that kind of claimed CR --- either that or a very low-lift cam --- which'd be counterproductive. Jack E/NJ
Thanks Guys, Sorry, I should have mentioned it's a v8-60. The heads are Edlebrock and stamped 105, which I am reading is the comp ratio on an otherwise standard chamber. I cc'ed them myself, crudely, and it does appear to match. Also read that at least some of the potential power gain with raised c/r is given back in lost breathing. They look good, but my iron heads with the chrome doodads look pretty good too. My main interest, being a 60, is power, or lack of.
torque the heads down with clay on the piston tops and remove and check clearence. If it is not at least .050 you might be to close. H&H flathead can fix that problem
I will, but at the moment I have a runner, plus I don't have a new set of head gaskets. In the mean time, this web site says the standard CR is 6.6:1 and the head volume is 41-43cc. http://restoreyourford.com/v860spec.shtml Using the formula I know of for CR, displacement of one pot, 278cc, plus say 42cc for the stock head equals 321 divided by 42 comes out to 7.6:1. Since the standard ratio is 6.6, I'm guessing they have about 8cc of head gasket/piston/valve area volume (278+50)/50 is roughly 6.6:1. I cc'ed the alloy head by filling with clay, s****ing flat, then dropping the resulting ball of clay in a graduated cylinder filled with water. I came up with somewhere around 20cc. Using the prior formula, 278cc + 20cc +8cc divided by 28cc is 10.9:1. Allowing for error in my clay measurement, I believe the 105 stamping is the correct ratio for these heads, and the old catalogs do say they were offered in that ratio, for alky probably. I'll do the full clay on the motor measurements when I get some new head gaskets, and also check my old iron heads. Thanks guys!
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