347 build up questions

send the pistons back for different ones. 12:1 is pretty much race gas compression. i think you want to be at 11:1 max for 93 octane.

where did you buy the kit (i hope not at a swap meet) ?

also have a reputable machine shop check all the clearances on the rod and main journals. i bought a "ready to install" 347 stroker from coast high performance (the good steel crank forged probe piston kit) and the crank journals all had to be regound and polished as they were way too big for the proper bearing clearance.
my machinist said the engine would have lasted a few thousand miles had we not corrected it.

build a relationship with a good shop and listen to what they tell you!

mancu5.0 said:

building 347 stock block .040 over the kit I bought has the dome (high compression) pistons I did not purchase cylinder heads yet but the kit gave me a rough estimate of compression ratio around 12 to 1 my question is there any way I could get the compression lower to an area where I dont need race gas and whats the highest I could go before I need race gas. The engine will be N/A any input will be greatly appreciated.

Click to expand...

Well you have a couple of options...

There are companies that can custom make you a head gasket to a specific thickness.

Or you can try and retard the cam timing. I've seen people run engines with 12.5:1 with iron heads and pump gas.

As far as what's the highest compression you can run, it totally depends on your cam.

mill the dome off the thing.