piston compression hight V rod length

When I built Manzos first K/B alky motor I used this combo for 176 cc heads, mind you that this was a steel motor, no one made an alum. block yet, 1/2 in stroker, 4.250 bore, Venolia pistons and rods, rods .250 longer, piston top of dome .777 out of the block, std.deck. pistons were ultra lightened.they took material from under the dome with a ball cutter to make piston lighter, and above wrist pin, if you use too heavy of a piston the motor won't rev fast enough, and thats the key to drag racing, how quick the motor rev's, not how much it rev's, 5.5 second isn't to long,quicker the motor gets to max r.p.m.'s quicker you go.Thats my story and I'm sticking to it.

 

thank you all for your information and help

cheers

 

I hate to thow a wrench in the gears. But the deck of a hemi piston is not necessarily where the dome breaks the plane of the deck of the piston. That will screw up your deck clearance and computed compression ratio. You need to have the job/part number for the piston so the manufacturer can tell you where the deck is.
The other thing you need to be aware of with big chamber heads is the chamber diameter at the deck. Not all of them are the same. For example. If your using a set of heads designed for a 4.310 bore with a 4.500 bore block, your going to have interference problems with the dome.

 

well i was not aware that the heads would also be diffrent chamber sizes diamater wise , one more thing to keep in mind , yes i have been struggling as to where the deak hight of the piston starts , i was using where the plan had changed , but this could well be wrong .
the old pistons were 4.28 bore and have no part number on them .dam it .
thanks guys .
i will send all the info i have to a few piston companys and see what comes back , i was keen to see if i could use an off the shelf piston to make life a little easer for the future .