milling heads for compression - 460 Ford Forum
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post #1 of 5 (permalink) Old 04-19-2011, 03:48 PM Thread Starter
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milling heads for compression

I've recently converted over to e85, and was thinking I would like to up the compression to take advantage of the fuel. With my c8ve heads and speed-pro flattops, the compression calc comes out to around 10.75:1. Anyone know how much can be safely machined and how much it would raise compression? I realize I will have to have the intake milled as well. Thanks.

83 cougar 466/c6/8.8 3.73s

73 torino gts/351c/c4

54 ford/390/c6
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post #2 of 5 (permalink) Old 04-19-2011, 04:49 PM
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Originally Posted by 83cougar460 View Post
I've recently converted over to e85, and was thinking I would like to up the compression to take advantage of the fuel. With my c8ve heads and speed-pro flattops, the compression calc comes out to around 10.75:1. Anyone know how much can be safely machined and how much it would raise compression? I realize I will have to have the intake milled as well. Thanks.
to me any cut over .040" your pushing the the gasket sealing . that would be around 6 to 7 cc's less
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post #3 of 5 (permalink) Old 04-19-2011, 05:40 PM
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The speed pro pistons have a short compression height and usually sit a significant amount below deck.

A flat top piston in a 460 at 0 deck will net about 11.7 to 1. You will at best gain .5 point by decking the heads where there is much more to be gained by 0 decking the block in addition to the increased squish effect.

How far below deck are your pistons now?



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post #4 of 5 (permalink) Old 04-19-2011, 06:06 PM Thread Starter
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I figured zero decking the block was better, however the engine is in the car, and since I have the intake off to do some work, I was thinking of pulling off the heads as well. However, if only a .5 a point is to be gained, I probably will not do it. I used a feeler gauge to measure how far down in the hole the pistons are when I assembled the engine, but I don't remember now. I do remember it seemed like quite a bit. Scott, you've got PM.

83 cougar 466/c6/8.8 3.73s

73 torino gts/351c/c4

54 ford/390/c6

Last edited by 83cougar460; 04-19-2011 at 06:20 PM.
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post #5 of 5 (permalink) Old 04-20-2011, 01:36 PM
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Cool

Quote:
Originally Posted by 83cougar460 View Post
I figured zero decking the block was better, however the engine is in the car, and since I have the intake off to do some work, I was thinking of pulling off the heads as well. However, if only a .5 a point is to be gained, I probably will not do it. I used a feeler gauge to measure how far down in the hole the pistons are when I assembled the engine, but I don't remember now. I do remember it seemed like quite a bit. Scott, you've got PM.
PM answered...



S

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