Looking for Info / Specs on Obsolete Mopar Piston
I'm an E-Body owner and have spent a lot of time on this Forum and have been impressed by the number of knowledgeable people on small block engine builds, what works, what doesn't.
So here's my problem.
Working on a 1970 340. Currently out of the car for a refresh. I'm trying to calculate the actual static compression of the current configuration.
Previous owner had the motor built with the Mopar Performance pistons P3690825 (made by TRW), advertised compression of 11.5:1. These pistons are obsolete and I can't find any published data on them. Motor has "O" heads, 72cc open chambers. Cam is the purple shaft, P4452761, duration @ 0.050 = 228/231, lift = 0.450I/ 0.455E.
I emailed TRW and they have no archived data on these pistons.
I'm looking for the dome volume and piston compression height. Anyone have those specs?
I tried measuring the dome volume, i.e., put the piston down a fixed distance in the hole, calculate the volume of the "perfect" cylinder at that depth, measure the volume with the burette and take the difference of the two readings. To calculate the "perfect" cylinder, the reference surfaces I used are the block deck and the quench flat of the piston. So the volume of fluid needed to fill the cylinder (after taking the difference in readings) would be the "net" volume of the piston dome.
Using this technique gives me a net volume of around 19.5 cc.
Does my technique makes sense? Anyone have data for comparison?
I'm an E-Body owner and have spent a lot of time on this Forum and have been impressed by the number of knowledgeable people on small block engine builds, what works, what doesn't.
So here's my problem.
Working on a 1970 340. Currently out of the car for a refresh. I'm trying to calculate the actual static compression of the current configuration.
Previous owner had the motor built with the Mopar Performance pistons P3690825 (made by TRW), advertised compression of 11.5:1. These pistons are obsolete and I can't find any published data on them. Motor has "O" heads, 72cc open chambers. Cam is the purple shaft, P4452761, duration @ 0.050 = 228/231, lift = 0.450I/ 0.455E.
I emailed TRW and they have no archived data on these pistons.
I'm looking for the dome volume and piston compression height. Anyone have those specs?
I tried measuring the dome volume, i.e., put the piston down a fixed distance in the hole, calculate the volume of the "perfect" cylinder at that depth, measure the volume with the burette and take the difference of the two readings. To calculate the "perfect" cylinder, the reference surfaces I used are the block deck and the quench flat of the piston. So the volume of fluid needed to fill the cylinder (after taking the difference in readings) would be the "net" volume of the piston dome.
Using this technique gives me a net volume of around 19.5 cc.
Does my technique makes sense? Anyone have data for comparison?
