Anyone use the 493 dish piston kit? I just called them and asked what compression the two kits had cause its not listed?? The guy said with 75cc the flat top would be 13.1 to1 and the dish would be 12.4 to 1.
this 12.4 to 1 with a dish doesnt sound right to me. why would they sell two kits that you need race fuel with? at less than one point apart. that makes no sense.
diamond has a list piston #52415 that would be about 11.2 to 1 in a 72cc head that would be perfect. Did I just get more bad customer service from mancini.....seems like the status quo for them, rushing you on the phone while shopping for a 1750 dollar item WOW

mine came with diamond pistons, and at zero deck with 1009 gaskets and 84 cc chambers it measured 10.33/1. mine's .040 over, so the 493 would be a little less.

thanks. can anyone venture a guess on what that would be @ 75cc?????????

No way that kind of compression... A zero deck flat top 493 with 75-75 cc heads and pistons with a -4 to -5cc valve relief would be in the 12.5:1 range....a 15 to 20cc dish would be close to 10.5-11:1 or so....just a quick guestimate from the old brain matter calculator.

thanks Bob, every time I call Mancini they talk to me like I just mugged their Grandma......
And even I could tell the #s were out of left field.
So the 493" is near the upper end of pump gas friendly then, thats all I'm looking for, not 9 to 1, but more like 10- 11 to 1?

This is accurate data, but I did NOT use an actual piston, just generalities based on what you asked.

# of Cyl. 8 COMP. WEDGE ENGINES
Bore 4.3500
Stroke 4.1500
Rod Len. 6.760
Gskt Bore 4.410
Comp. Gskt .0390
Block Deck Ht. 10.7200
Top ring down 0.260
Chamb. Vol. 75.0
Dome (-) Dish (+)5.00
Piston / deck 0.005

Total volume 1102.97
Cylinder volume 1010.69
Clearance volume 92.28
Gasket volume 9.76
Top ring volume 1.30
Deck volume 1.22
Piston top land 4.305
1/2 Stroke 2.075
Comp. Ht. 1.880
Cubic Inches 493.41
Compression ratio 11.95

With a 15.0cc dish:

# of Cyl. 8 COMP. WEDGE ENGINES
Bore 4.3500
Stroke 4.1500
Rod Len. 6.760
Gskt Bore 4.410
Comp. Gskt .0390
Block Deck Ht. 10.7200
Top ring down 0.260
Chamb. Vol. 75.0
Dome (-) Dish (+) 15.00
Piston / deck 0.005

Total volume 1112.97
Cylinder volume 1010.69
Clearance volume 102.28
Gasket volume 9.76
Top ring volume 1.30
Deck volume 1.22
Piston top land 4.305
1/2 Stroke 2.075
Comp. Ht. 1.880
Cubic Inches 493.41
Compression ratio 10.88

Thanks alot

The reason I remember is I built a similar engine a few years back.
It was a RB engine deck height deck to 10.72 inch. back then there wasnt a large selection of stroker cranks with 4.15 stroke.. You had MP and then Eagle. Both were standard mopar rod pins...Anyways I used Probe pistons with a CH of 1.85 the pistons were in the hole .005-.008 inch and used Eagle 6.76 H=beam rods.
Those Probe pistons have a generic -4cc valve relief, and I was using the PT replacement head gasket with Box stock Edelbrock RPM heads...
Compression with the 84cc heads was 10.8-11:1 and run just fine on pump 92 gas.