Head Volume
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Joined: Aug 2004
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Head Volume
Can anyone tell me what the combustion chamber volume of my 86 cast iron heads is? Will swapping them out to the late 86 aluminum heads help that much? Anyone know who makes the stock pistons and rings.
The engine is sitting on a stand. It has very little wear. I pulled it because it had a massive oil leak from the upper rear of the engine. When I tore it down, I could find no obvious source of the leak.
How much can I raise the compression and still run pump gas? Stock is 9.0 and runs regular OK.
Any help or thoughts is appreciated.
The engine is sitting on a stand. It has very little wear. I pulled it because it had a massive oil leak from the upper rear of the engine. When I tore it down, I could find no obvious source of the leak.
How much can I raise the compression and still run pump gas? Stock is 9.0 and runs regular OK.
Any help or thoughts is appreciated.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Originally Posted by lefoy84
Can anyone tell me what the combustion chamber volume of my 86 cast iron heads is? Will swapping them out to the late 86 aluminum heads help that much? Anyone know who makes the stock pistons and rings.
The engine is sitting on a stand. It has very little wear. I pulled it because it had a massive oil leak from the upper rear of the engine. When I tore it down, I could find no obvious source of the leak.
How much can I raise the compression and still run pump gas? Stock is 9.0 and runs regular OK.
Any help or thoughts is appreciated.
The engine is sitting on a stand. It has very little wear. I pulled it because it had a massive oil leak from the upper rear of the engine. When I tore it down, I could find no obvious source of the leak.
How much can I raise the compression and still run pump gas? Stock is 9.0 and runs regular OK.
Any help or thoughts is appreciated.
I took the heads to a machine shop that does a regular business in race engines - NOT just a normal machine shop that does mostly dealership work.
I had the heads ANGLE milled - NOT flat milled - to the max. I believe .080 was the max that could be cut from mine because of the location of the water jackets.
Angle milling was chosen because it maintained the correct intake manifold alignment, whereas flat milling will call for the intake surfaces to be milled also.
Have the shop cc one chamber before and the same one after the milling and use those numbers to calculate the CR.
I still ran 93 pump gas.
Jake
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by lefoy84
Can anyone tell me what the combustion chamber volume of my 86 cast iron heads is? .
Originally Posted by lefoy84
The engine is sitting on a stand. It has very little wear. I pulled it because it had a massive oil leak from the upper rear of the engine. When I tore it down, I could find no obvious source of the leak.
Originally Posted by lefoy84
How much can I raise the compression and still run pump gas? Stock is 9.0 and runs regular OK.
RACE ON!!!
Drifting
Joined: Apr 2003
Posts: 1,379
Likes: 4
From: rome ny
Originally Posted by JAKE
I had the heads ANGLE milled - NOT flat milled - to the max. I believe .080 was the max that could be cut from mine because of the location of the water jackets.
Angle milling was chosen because it maintained the correct intake manifold alignment, whereas flat milling will call for the intake surfaces to be milled also.
Jake
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Pro
Joined: Aug 2004
Posts: 623
Likes: 1
Is it worth it to swap out the cast iron heads for stock aluminum ones. If I do this what will the compression be with the stock pistons? What kind of performance increase will I see?
Sorry for the questions, but I am trying to learn more about engine tweaking.
Sorry for the questions, but I am trying to learn more about engine tweaking.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by lefoy84
If I do this what will the compression be with the stock pistons?
Originally Posted by CFI-EFI
The 58cc '86 aluminum heads will get to you around 10.2 to 10.3, depending on your deck height and gasket choice. You should be OK even with the stock cam, due to the aluminum heads.
RACE ON!!!
RACE ON!!!
