Thread: piston and rod questions

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I got a screamin good deal on a set of venolia forged pistons for my Buick 455, they are designed to be used with a BBC 6.800 inch rod. i was doing some figuring trying to determine how far the new pistons and rods will be in the hole compared to the stock setup..something aint adding up or i dont know what the hell i'm doing. here is what i have

stock pistons have a 1.955 compression height (pin height)
stock rod is 6.600 long, this should give me a total length from rod journal centerline to piston top of 8.555 correct?

new pistons have a 1.620 compression height (pin height)
new rods are 6.800 long, crank will be offset ground for an additional .050 stroke to take advantage of the .050 smaller rod journal on the bbc rod so this means i would add .025 to my measurement correct? that gives me a total from rod journal centerline to piston top of 8.455 correct? this means that my piston will sit down .100 farther in the bore than a stock piston if i am correct?

this is true... so you would actually be losing compression while increasing stroke and also increasing cylinder volume.... great if you're planning on adding a super charger

thats what i was afraid of.. the stock length setup is typically .040 in the hole on a stock block..that means my new stuff would be .140 in the hole which is a good recipe for detonation. i think i will go with the BBC 6.900 rod and that will cure that problem. i paid 300.00 for a brand new set of pistons that retail for nearly 1000.00 so i'm not to broken hearted

if you happen to come across another super deal like that on some small block ford pistons let me know.... i'm replacing my bottom end right now due to a nice little mess of spun bearings and twisted/snapped rods