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Discussion Starter #1 (Edited)
I have a 1975 chev 350 out of a truck. I was told the stock pistons have a 13cc dish in the top of the piston, I assume this was to lower compression for the smog motors. I have replaced these pistons with flat top units that have valve reliefs cut into the tops. The crank and rods were left stock. The stock heads with 76cc chambers were replaced with Edelbrock RPM Performer aluminum 64cc heads. The cam I used was the GM RV cam. I have two questions...what would my compression ratio be and how much more cam lift could I safely add with roller rockers that have a 1.6 ratio? Anyone know the cam specs for the RV cam? Okay I said two questions but I guess I asked three. Thanks for your help.
 

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With .030" overbore, .015 deck height, 5 cc valve releifs, .040 head gasket thickness, and the 64 cc chambers, you have 10:1.
 

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You got a leaky spark tube...
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Do you know what the compression height on the pistons are? Some members on here have mentioned the "rebuilder" pistons that have 4 valve reliefs and are basically stock replacement pistons with .020" knocked off the top. If the block deck height is left at 9.025" this would lower your compression. You're probably looking at around 9.25-9.7:1 depending on what pistons you have.
 

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Discussion Starter #4
My pistons do have the four cuts in their tops. I don't know too much more. My friend ordered the pistons for me but he passed away before we gat around to talking about compression ratio etc. Sure wish he was still here. Thanks
 

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You got a leaky spark tube...
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Do you have a part number or anything?
Are the heads on the engine now? If they're not then you can measure how far down the hole they are when the pistons are at TDC. That would be a start.
 

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Discussion Starter #6
The engine is complete and running. I am more concerned with camshaft selection. I don't want to select a cam that may cause the valves to hit the top of the pistons. The rv cam seems to run okay but it doesn't have the raunchy sound of a hi-perf cam. I am going to replace my harmonic balancer before this spring, so I was thinking I might just slip in a cam while the balancer was off. I have a stock converter in my 350 turbo so I am limited as to how much cam I can put in. I have crane 1.6 roller rockers so that is going to help build a little extra lift. Any recommendations?
 
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