I have to order a MSD chip .
On the form i place to order the chip .
I have to note the compression ratio.
I have a set of CP pistons with cam cut outs.
What is the best way to find this ratio.
I have a set of old pistons that i could measure the bowl capacity on.
The car is a 2wd with a 4x4 head YB.

Thankyou
ok i have been on the calculaters.
31cc piston bowl.
46 cc head (this is going of a picture of a head and measurements on passionford)
91.3 mm bore x 91.3mm x pye(3,14) /4 x 76.9 stroke
guessed at 5cc head gasket
i am looking at 503 cc / 82cc =7.13:1
i would like to no the cc of a standard piston as they were about 8.1:1 standard.
If the bowl is up or below 31 it would help me become more confident with my results.
I have calculated 100 times and each site gives me a diffrent outcome.
mainly between 6.3 and 7.3.
Ok read the tech passionford and you add the 503cc to the tdc volume /by tdc.
This is why I had such low compression.
I have just the head cc and gasket to master and I can order my chip.
I have a bd14 inlet cam so the tuners will add this into the equation for non static compression .due to the cam being open longer.

Regards Craig