CC'd Heads

[nivvy]

Im thinking of buying these Iron Max Wedge ported heads but the owner says they are milled down .060 and are appx. 78cc'c granted i still want to run on pump gas 94 octane actually....

My Deck height is .013..what thickness head gasket do I need to acheive 10.1 compression?

thx

[Chryco Psycho]

http://www.csgnetwork.com/compcalc.html

enter you #s in to here

[nivvy]

I have on of those programs on my dyno sim. chyrco but I dont know what my piston dome volume is? where do I find that spec out?

[Chryco Psycho]

are the pistons flat tops ?   if so there is no dome volume

[nivvy]

They ar J&E Flat top pistons with valve reliefs cut in them...

[moper]

Sort of true. the valve releifs can represent a bit of "dome volume". In many calculators, you have "dome volume" where positive numbers equal a dish or vavel reliefs, and domes are represented by a negative number. So a flat top ,with typical valve reliefs would be inputted as "6cc" (my J&Es were 6 as I recall), where a large dome and the offsetting valve reliefs would go in as "-13cc".

By my calculator, you will end up with 10.7 with the Felpro thick .043 gasket. So you may look into even thicker. MLS gaskets need an ultra smooth finish to work well. So the heads and block's deck surface may need to be refinished.

[nivvy]

How are you coming up with 10.7

Bore         4.375
Stroke       4.150
cc           78
dome         6
gsk bore
gsk thckns

[nivvy]

I must not be entering data right or something?

[nivvy]

 

[Killer_Mopar]

I got 11.55....this is what I punched in:

1-inches
4.375  - bore
4.15 - stroke
4.38 - gasket diamter
.043 - gasket thickness
78 - CC of heads
-5 - negative cc valve reliefs in piston (could be different, I used the numer from JE website)
.013 - deck height

[Killer_Mopar]

You can get the compression down to 10.3 if you use a .095 SCE copper gasket, but I wouldnt buy those heads unless they are a really good deal.

[moper]

Ok, sorry, dotn ask what I did...lol...I can just say I messed it up.

Using your numbers, and a .043 Felpro blue gasket, that has a 4.38 bore as I recall, and comes to 11.45:1.

Like was said, the .094 gasket is usedyou can get it down. But really, they are just too much with the pistons used. You can also polish the chambers and make them bigger too.

[nivvy]

hmm.when i punched in info I got 9.87  -  1  using the link above chryco suggested??

1
4.375
4.150
4.380
.043
78
-5
.013

9.87 - 1   

[moper]

Using CPs page I still get 11.5something...

[nivvy]

you must not be clicking on calculate CR  button?? because it said 11.5 for me until I clicked on that button..