decking heads

militarymustang88gt · 03-26-2009, 01:11 PM

how much more compression would i be looking at if i decked the heads like .040". is it going to be like a 58 going to a 56cc or some thing like that or a little more. just trying to get an idea of how much i am going to need to take off to get to where i wanna be at.

coupe · 03-26-2009, 01:58 PM

What heads? The volume removed is going to be a simple calculation of the area of the combustion chamber shape (sq. inches) x the .040 (inches)..giving you cubic inches. Then convert to cc.

To get the area of that chamber, I would estimate an equivalent circle radius (squared) x pi (3.14159).

militarymustang88gt · 03-26-2009, 02:09 PM

i just had some e7s i was looking at porting and decking for a little cheap motor i could try and blow up for some fun........ and to see how much hell a rebuilt 50 could take before letting loose.

coupe · 03-26-2009, 02:13 PM

E7's...I will get a "reduced volume" in cc's (with a .040 cut) for you when I get home. I have some E7's there.

1Quik85GT · 03-26-2009, 04:25 PM

you need to check and see how far the piston is in the hole!!! getting compression isnt just in milling the heads

EHardy1971 · 03-26-2009, 04:55 PM

You also have to calculate compressed thickness of the head gaskets too. FWIW,I had my GT40's milled .030",which took them from 64cc's to 60cc's,and a CR of 9.8:1.

militarymustang88gt · 03-28-2009, 10:48 AM

yeah it is a stock rotating assembly i will be using. i am just going for like 10.5:1 then put a 150 shot on and see how long it will last.

BAD INT · 03-28-2009, 12:14 PM

stock cam?

militarymustang88gt · 03-29-2009, 11:19 AM

maybe not. not sure.

03-26-2009, 01:11 PM	#1
militarymustang88gt Senior Member Join Date: Jun 2007 Location: bham and auburn Posts: 337	decking heads how much more compression would i be looking at if i decked the heads like .040". is it going to be like a 58 going to a 56cc or some thing like that or a little more. just trying to get an idea of how much i am going to need to take off to get to where i wanna be at. __________________ finally got my avatar. it is the white one.

03-26-2009, 01:58 PM	#2
coupe Super Moderator Join Date: Dec 2004 Posts: 6,313	What heads? The volume removed is going to be a simple calculation of the area of the combustion chamber shape (sq. inches) x the .040 (inches)..giving you cubic inches. Then convert to cc. To get the area of that chamber, I would estimate an equivalent circle radius (squared) x pi (3.14159). __________________ " If you can't explain it simply, you don't understand it well enough. " - Albert Einstein

03-26-2009, 02:09 PM	#3
militarymustang88gt Senior Member Join Date: Jun 2007 Location: bham and auburn Posts: 337	i just had some e7s i was looking at porting and decking for a little cheap motor i could try and blow up for some fun........ and to see how much hell a rebuilt 50 could take before letting loose. __________________ finally got my avatar. it is the white one.

03-26-2009, 02:13 PM	#4
coupe Super Moderator Join Date: Dec 2004 Posts: 6,313	E7's...I will get a "reduced volume" in cc's (with a .040 cut) for you when I get home. I have some E7's there. __________________ " If you can't explain it simply, you don't understand it well enough. " - Albert Einstein

03-26-2009, 04:55 PM	#6
EHardy1971 Trunk Monkey Join Date: Jun 2007 Location: Home Posts: 5,708	You also have to calculate compressed thickness of the head gaskets too. FWIW,I had my GT40's milled .030",which took them from 64cc's to 60cc's,and a CR of 9.8:1. __________________ Eric 89 LX Coupe-Juiced 01 Lightning-Boost 06 TBSS

03-26-2009, 04:25 PM	#5
1Quik85GT Senior Member Join Date: Apr 2005 Posts: 895	you need to check and see how far the piston is in the hole!!! getting compression isnt just in milling the heads

03-28-2009, 10:48 AM	#7
militarymustang88gt Senior Member Join Date: Jun 2007 Location: bham and auburn Posts: 337	yeah it is a stock rotating assembly i will be using. i am just going for like 10.5:1 then put a 150 shot on and see how long it will last. __________________ finally got my avatar. it is the white one.

03-28-2009, 12:14 PM	#8
BAD INT Senior Member Join Date: Oct 2007 Posts: 184	stock cam?

03-29-2009, 11:19 AM	#9
militarymustang88gt Senior Member Join Date: Jun 2007 Location: bham and auburn Posts: 337	maybe not. not sure. __________________ finally got my avatar. it is the white one.