It would seem head gasket volume is missing from the factors that produced the stated 9.55 compression here. Actually in any of the compression formulas presented here other then my example, to be dead nuts on one could add another 2 CCs of volume which would then properly reflect the ring land volume that is being left out here.
head gasket was a stock .017 i put in 3.85 for gasket bore, i should have stated about 9.55. the ring land volume is normally built in with the calculator formula
Piston height was 1.283" and rod length was 7 inches. The rods are a Scat FHF rod that uses the Buick bearing and a 3/4" wrist pin that weighs 71.5 grams. Standard ring package. The entire reciprocating assembly is very light. I'm showing a rod weight of 4055/159. Joe, unfortunately I have plans for the 300 heads, as I have a iron head 2bbl 300 (the Mule) in good shape in the car now and intend to use them on it. That will leave me with a set of low mileage iron heads that I will be able to dispose of. I have also made the jump to roller cams and plan to not only use one in the 340 but eventually in the Mule as well. I will probably stretch this work out though as the Stroker 300 now only needs rockers and the blower intake fabricated. Hopefully the flat tappet cam in the Mule will make it until that is finished. The one that came out of the 340 was in very sad shape, but the one in the Mule is OEM. I've used those online calculators and consider them to be a benefit. Some are a little better than others and it is certainly easier to just plug in the numbers than it is to do all the math and you always wonder if you've made a mistake. Best to do it both ways of course. Have to watch the negative numbers too, and the actual measurement of the hole diameter of the head gasket also makes a small difference but I think the 3.950 number is pretty close. In either case you can always either change the formula or plug in fake numbers to find things like a desired dish volume for a given CR. Don't neglect dynamic CR also. That can make a pretty big difference in your cam selection. Jim
i went the opposite of Jim with a mild 340 street engine in my 66 skylark. I was impressed with the little 340 it turned out good with a very low 14 second with 3.23 gears and 2-speed switch pitch tranny. talking with Dave Nelson who worked with Joe Sherman racing, actually got to talk with Joe Sherman a little about camshafts. Dave built a budget 300 stroker that was featured in one of the hot rod magazines. I used his same set up with bigger valves and chevy roller rockers in the iron 340 heads same as 300 heads. with mild porting on the heads and on the intake manifold. with a very mild comp cam, Race tech made me some custom pistons .030 over 1.88 compression height and 17.5 cc d-dish. with pistons 5 thousand in the hole with a little block decking. compression came out to about 9.75-9.8. to do it over again i would keep the compression at 9.5 and a slower advance curve that i put in distributor because of keeping the dreaded pinging under control. my friend had a 1967 GS 340 back in the day, being all stock it was not very fast
Update- Yesterday I brought the block to the machine shop. Nothing fancy here- it'll get cleaned up and magged. If all is good I'm going to take .030 off the deck, it'll need one sleeve and I'll deburr it after. That should bring me about 9.3:1 with the stock pistons. The heads will get a basic valve job with new springs. I'll touch the ports up as well but nothing crazy.
Bummer of all bummers. The 340 evidently froze at some point when it was under the bench. It has several cracks and is not usable. So the hunt is on for a 340 block.. any leads appreciated.
