.581 lift and milling heads?
05-23-2003, 07:07 PM
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.581 lift and milling heads? If you have a cam with lift of .581 is it still safe to mill the heads about .030? or will this reduce the piston to valve clearence to unsafe levels? this is assuming the pistons don't have valve reliefs.
05-23-2003, 07:08 PM
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Re: .581 lift and milling heads? The only way to truely know is to clay, that is a gaurnteed way to let you know..
With .30 heads and a .591 lift I smacked the pistons w/the valves...
With .30 heads and a .591 lift I smacked the pistons w/the valves...
05-23-2003, 08:31 PM
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Re: .581 lift and milling heads? As BIGBOS said, the only way to know for sure is to check them yourself.
Personally, I wouldnt go with a .030 mill on that cam. I went with a .020 mill on a .571 cam, and I was okay.
Personally, I wouldnt go with a .030 mill on that cam. I went with a .020 mill on a .571 cam, and I was okay.
05-24-2003, 06:27 AM
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Re: .581 lift and milling heads? Of course the for sure way is to do the clay test 
But to give you some hope 
I just clay tested mine, I'm running the ASA cam, it has 525/525 of lift, I have the Crane 1.8 ratio rockers on top of that which take it up to approximately 555/555 of lift, I have 2.02 and 1.6 valves, and my heads were decked a total of .040 
I had over .110 of clearance. So for sure I would do a clay test. It doesn't take that long. Just put the head on w/no gskt, stick some clay on the piston, I sprayed some WD-40 on the top of the clay so the clay wouldn't stick to the valves. Then put the head on put a few bolts or studs in, just to hold it on. Bolt down the rockers for the two cylinders and rotate the motor about two full crank rotations. Undo all of the bolts and be very careful on how you take the head of as to not tear the clay. When you get the head off you should have two indentations in the clay, cut down the center of them, then take your micrometer, and measure the lowest point in the indentations to the top of the piston, and then add about .054 I think for the compressed gskt thickness(if using stock head gskts) and that should be your clearance. Hope this helps out and good luck!!!! 
But to give you some hope I just clay tested mine, I'm running the ASA cam, it has 525/525 of lift, I have the Crane 1.8 ratio rockers on top of that which take it up to approximately 555/555 of lift, I have 2.02 and 1.6 valves, and my heads were decked a total of .040 I had over .110 of clearance. So for sure I would do a clay test. It doesn't take that long. Just put the head on w/no gskt, stick some clay on the piston, I sprayed some WD-40 on the top of the clay so the clay wouldn't stick to the valves. Then put the head on put a few bolts or studs in, just to hold it on. Bolt down the rockers for the two cylinders and rotate the motor about two full crank rotations. Undo all of the bolts and be very careful on how you take the head of as to not tear the clay. When you get the head off you should have two indentations in the clay, cut down the center of them, then take your micrometer, and measure the lowest point in the indentations to the top of the piston, and then add about .054 I think for the compressed gskt thickness(if using stock head gskts) and that should be your clearance. Hope this helps out and good luck!!!!
05-24-2003, 07:07 AM
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Re: .581 lift and milling heads? Thanks fellas! I figured that this would need to be clay tested but thought I would ask and get some feedback. The setup is not for me but for a guy we just did some ported heads for who already has the cam and was asking me about using 1.8 rockers or milling .030 off the heads. I knew for sure the rockers would cause him problems but wasn't 100% sure about the milling though I knew it would be close. My son it the company expert but is out of town for the weekend.
05-24-2003, 08:08 AM
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Re: .581 lift and milling heads? Well, as you know Scott my setup is going to be Comp Cams 224/224 .581/.581 LSA:114 with S2 5.7 heads with a C/R of 11:1 (I think that is .040???). I was told by Jay at Absolute Speed that I would not have any problems since I choose to go with the 114 LSA. Guess we will know next week.