I am looking for part numbers for a set of pistons. What compression are you running on the street with aluminum heads? I have the Indy aluminum heads for the next motor and a 600 lift solid roller and a 4 speed.

My 572 Hemi will be 13:1

Mine is 11:1. CHIP

The only piston i have found with a part number is a

J and E
131834

Just under 13 to 1 here with Indy EZ's and Ross "0" decked flat tops with valve reliefs, but I mix 110 leaded racing fuel with my pump gas. It cost a bit more to fill up, but there's nothing like high compression, and I only plan on burning a tank or two a month.

Is the next motor a "Wedge" or a Hemi motor? If wedge I run 10.5 to 1 in the 464 C.I.(440 block with Eddy RPM heads) motor and 10.29 to 1 in the 518 with the CNC ported Eddy RPM. I run straight pump gas in both, no problems so far. I'm temtped to switch heads on the 518 to a set of 440-1 with smaller chambers(64 cc versus 84 cc on the Eddys) and up the compression to 11.5 or so, I haven't done the math yet on that parts swap so I don't know the exact compression numbers yet. The bad thing on the 518 motor is it has a set of 22 CC dished piston at zero deck so the quench is non existenct

11.6:1 in my Hemi on pump gas here...But you weren't specific if you were talking wedge or hemi..

11.7 comp here pump gas only, 606 hemi,tryed a mix of race gas and slowed down!

It is another hemi. Sorry about that.

Durations on the cam have some affect this is my 3rd pump gas (94 hear) motor first was 11.75 to 1 452 with an ultradyne 263/271 duration cranking compressions were 194 to 202 and no detonation.
next (same heads) was 11.5 to 1 542 274/282 roller
160 cranking probably could have used 87! LOL
Now have 452 with a 272/282 roller 11.5 to 1 (or 12 with the aluminum rod growth??) cranks 160 to 170 cold could probably run 89 or 92 but I use 94 runs great! Indy wedge! same head on all motors.
I think if you keep the cranking compression below 190 with aluminum heads you are good for 93

You really need to post more about the combo and the intended use of the vehicle before any recommedations can be made on CR. What fuel type? What cam? Bore? Stroke? etc? I run 12:1 in a 572 hemi. I wouldn't try to use a shelf piston with an indy head and try to get any kind of compression out of it. We can spec you a diamond custom piston to get exactly what you need.

do you have the intake close point for the cam?

Are you figuring the actual compression ratio of the motor or ordering pistons by the compression ratio and putting them in thinking that is the actual mechancical compression ratio? I have found out by pouring the cylinder volume with the pistons sealed below TDC and figuring the calculated cylinder volume and then figuring the compression ratio that the compressio ratio was not anywhere close to what the pistons where suppose to be The 426 Hemi heads and the dome shape and size make it real hard to get the compression ratio correct without doing the dome volume check Now as far as pump gas compression ratio the hemi motors can probally get away with a lot more than a wedge due to the combustion chamber size and shape and the spark plug location

Yup Cab is right CC the head, CC the cylinder with piston down X amount to be below the dome - the calculated amount of that down volume and head gasket cc is the only true measure to calculate compression ratio

1969 road runner
dana 60 3.54 gears
4 speed
street car
world 4.25 bore block
callies 4.15 crank
manely rods 6.86 long 1.031 pin
stage V two four intake
msd 8546 distributor
msd 6al2
msd plug wires
Indy aluminum legend heads
comp cams solid roller camshaft


Part # Description 426-C1-
H-R1-ST ROLLER: Street much smoother idle than H-R1 perfect
for E.F.I or Supercharger
RPM range 2500 to
6500
Dur@ .050
(Int/Ex)
248/248 with 1.6/1.55 .616/.597 108


comp roller lifters
indy timing set
two edelbrock 750's
stage V valve covers


I am just looking for an "as advertised compression ratio"


I am going to just order the JE 11.7 to 1 with the head CC's according to the ad for the heads being 170cc it will be 11.1 according to the tech's at JE