Thread: compression question?

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i plan on doing some work to my motor over the winter and had some questions someone may answer...

i had my motor rebuilt 2 years ago and i just had the pistons re ringed i was on a budget... now i've upgraded my 305 heads on my 350 to a set of double bump heads milled down to 60cc. its a a four bolt main 480 lift cam and airgap intake..
it currently has stock truck pistons with the dish and valve reliefs in them... i wanna put some good pistons and rods in it but am not sure what to run..i'd like around 10:1 compression but am not sure what pistons i need to get it.. the block hasnt been decked and i'm not sure what i'm running for comp now??? with a 60cc combustion chamber what kinda pison design do i need...how much should i bore it?? what kinda piston forged?hypertectic?? ohyea its stock bore...

I'm not sure about the specific pistons you are asking about but the advise I have is to be careful when upgrading compression, especially if iron heads. You dont want to run over 9:1 unless you can commit to running race fuels. You could go to 10:1 with aluminum with out much problem on pump gas. The 60cc chambers will increase the compression a good bit also.

I'm assuming you are running a cam something like this....
http://www.cranecams.com/?show=brows...tType=camshaft
Notice that this cam works with a c.r. of 9.5 to 11.0 to 1, so that's where you want to be. If you bore the block 0.030" and use Keith Black part number KB193 hypereutectic pistons with a 12 cc dish, zero the deck and use a 0.039" compressed gasket thickness, you'll have a squish of 0.039" that will allow you to run on premium pump gas at a c.r. of 9.97:1. The only way you can get away with it is with the tight squish.

If you don't pay attention to the squish, then you'd better pay attention to s10streeter.

If you zero the deck, pay close attention to the intake/head sealing to prevent a vacuum leak. Follow my plan....
http://streetmachinesoftablerock.com...opic.php?t=350