The maximum amount I can mill off my heads
12-21-2007, 07:59 PM
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The maximum amount I can mill off my heads I am toying with building a gen III 5.3 for my 1987 Monte Carlo SS. I am converting it to the Edelbrock carb set up (w/ a 800 cfm AVS Thunder Series carb). I have installed the Edelbrock #2216 cam. The spec are 540/540 lift and a 110 lobe sep. I know it's not a LS1 but I wanted to build something a little cheaper for my Monte. I have finally finished my Z28 and had to start another project.
Does anyone know how much I can mill off without getting into valve to piston clearance problems.
The 5.3 has a stock CR of 9.5 to 1 and the chambers are 61cc.
Any help would be great.
Thanks,
Mark
Does anyone know how much I can mill off without getting into valve to piston clearance problems.
The 5.3 has a stock CR of 9.5 to 1 and the chambers are 61cc.
Any help would be great.
Thanks,
Mark
12-22-2007, 09:25 AM
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i've been told by a machine shop guy, that you can mill .125 off of an sbc. depending on the shape of the combustion chamber he said it would raise the compression ratio around 1 and 1/2 points. they MUST be angle milled and you would also need to have the intake milled. i've had my heads cut about .035 and i had too slot the intake bolt holes. i'd still check the piston/valve clearance if i was cutting that much. by decking the block you can also raise the compression. you should have about a 4% gain in h/p for every point of compression gained.
01-05-2008, 01:27 AM
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Head milling I would not go more than about .060 as the head castings are not that great. If you are looking for extra power cheap, mild port the heads get a good 7 angle valve job and maybe stroke the engine...with an 800cfm carb ( way big ) you could easily go to 430" and still have more air than you need.
01-05-2008, 09:13 AM
#5
If you're staying with stock cubes that carb is way too big IMO.
You did not list the duration figures of your cam, which plays a huge part of piston/valve clearance. How much advance is in the cam? Moving down the ICL (Intake center) is going to reduce PTV clearance also.
Depending on the duration of the cam, you should be able to go .020-.030 off the head without problems. Never assume anything, and check PTV anyway regardless of what anyone tells you will or will not fit. Every motor is different, and some clear while others don't.
You did not list the duration figures of your cam, which plays a huge part of piston/valve clearance. How much advance is in the cam? Moving down the ICL (Intake center) is going to reduce PTV clearance also.
Depending on the duration of the cam, you should be able to go .020-.030 off the head without problems. Never assume anything, and check PTV anyway regardless of what anyone tells you will or will not fit. Every motor is different, and some clear while others don't.
