Hello everyone, im measuring the compression on my '68 383, I was wondering if anyone knows the factory piston dish CC?
Thanks!

Hello Ori, JohnRR would (likely) be the man with that info, he's the 383 guru

'69 shouldn't have a dish or valve reliefs.

Thanks Robert Sorry I mistyped that. Its a 1968 instead of 69

same piston. pretty sure pistons are the same '68-'70.

2bbl had a dish

BUMP!

I want to say it's 8cc. I have a piston but never measured it.

The difference in ADVERTISED ratio between the 4bbl engine and 2 bbl engine in 68/69 is .8 , to get that difference using a compression ratio calculator I come up with 8.5cc.

Well you have a couple of ways to find it.

You could measure the diameter and depth if it is a cylindrical shape with a flat bottom. I'll calculate the cc with that data.

Or you could use the Mopar method divised for Hemis where you put the piston some precise distance down, seal up the ring area, and cc the block. Subtract the volume of the cylinder and you have ccs of the dish.

You could even set the piston up level and just cc the dish. That's probably the quickest method.

I'm surprised JohnRR hasn't answered this post, maybe it's beneath him to talk about 2-barrel engines? He knows more about stock 383 pistons than about anyone else here.

R.

I posted 5 mins before you did

Ori if you have the piston in front of you, you might measure the diameter and depth of the trough as close as you can cuz it sure ain't gonna be a perfect geometric figure. if you get a cubic inches number (length x width x depth) then multiply that by 16.387064 to get CC's. EDIT How about this! Ori fill the trough with clay (dead even level) then take the clay out (all of it) & have your burette filled to maybe 50 CC dead even on the 50 CC mark then drop the clay in & see how far the water level rises. (knead the clay into a thin rope so it dont catch on the sides of the burette). MORE EDIT forget the burette, take the clay out & knead it into a perfect square then measure the sides (l/w/h) & do the math. MORE EDIT roll it into a ball in the palms of your hands cuz that will be way easier than molding it into a square then put the math on that, volume = 4/3 x (Pi x radius cubed) & the radius will be 1/2 of the balls' diameter then convert that cubic inch number you get into CC's. MORE EDIT Hey Dog, John is a post ho & he would not pass up an opportunity to kick his numbers' higher & he does know the 383 piston ins/outs

8.9cc's

Did mine last year

thats too easy! Hey thanks for helping my buddy Ori out