Piston to Valve Clearance Question
10-10-2003, 06:22 AM
#1
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Piston to Valve Clearance Question
Ok, here's the deal. I like my 224/230, but I'm already wanting something bigger. I know my heads will easily support 400 RWHP, so I'm looking at a cam that will do it. 230/230 is up there, but I'm really considering the GM847 grind. Now here's the question:
I had the heads milled .005 for a slight increase in the compression ratio. Am I going to have to undercut the valves due to the almost .600 lift on the 847 cam?? Or will I be all right??
I had the heads milled .005 for a slight increase in the compression ratio. Am I going to have to undercut the valves due to the almost .600 lift on the 847 cam?? Or will I be all right??
10-10-2003, 07:18 AM
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Originally posted by grygst76
.005 is nothing, you will be fine AT less then .600. If it is at or .590 you will have to check piston to valve clearance.
.005 is nothing, you will be fine AT less then .600. If it is at or .590 you will have to check piston to valve clearance.
10-10-2003, 07:31 AM
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Originally posted by Fastbird93
Ummmm so which is it that I'll be chancing it?? .600 or .590??? I believe the lift on the exhaust with a 1.6 for the 847 is .595??
Ummmm so which is it that I'll be chancing it?? .600 or .590??? I believe the lift on the exhaust with a 1.6 for the 847 is .595??
10-10-2003, 08:44 AM
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Well, I'm using 1.6 rockers. That .595 was with 1.6 rockers. And I already have brand new springs good to .600 lift on the heads. The whole setup doesn't even have 1000 miles on it yet.
10-10-2003, 08:51 AM
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Originally posted by Fastbird93
Well, I'm using 1.6 rockers. That .595 was with 1.6 rockers. And I already have brand new springs good to .600 lift on the heads. The whole setup doesn't even have 1000 miles on it yet.
Well, I'm using 1.6 rockers. That .595 was with 1.6 rockers. And I already have brand new springs good to .600 lift on the heads. The whole setup doesn't even have 1000 miles on it yet.
10-10-2003, 09:31 AM
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I realize that I'm going to need better springs. That goes without saying. It's like using hotcam kit springs with a CC305. You could, but would you want to??
Back to the original question, I really need to know if I'm going to need to undercut the valves or not.
I'm actually quite happy with my setup as it is right now, but I'm very strongly considering the bigger setup because A: I want to go over 400 at the wheels, and the heads will easily do it, and B: Emissions are now a non-factor for me.
Back to the original question, I really need to know if I'm going to need to undercut the valves or not.
I'm actually quite happy with my setup as it is right now, but I'm very strongly considering the bigger setup because A: I want to go over 400 at the wheels, and the heads will easily do it, and B: Emissions are now a non-factor for me.
10-10-2003, 10:20 AM
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Fear not Fastbird93. my heads have been milled over .030, I run thinner headgaskets and the GM847 cam with larger valves. My piston to valve clearance was .085" Typically you want atleast .100 exh and .080 int for valve clearance. You should be fine.
10-10-2003, 12:09 PM
#13
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Originally posted by Grease
Fear not Fastbird93. my heads have been milled over .030, I run thinner headgaskets and the GM847 cam with larger valves. My piston to valve clearance was .085" Typically you want atleast .100 exh and .080 int for valve clearance. You should be fine.
Fear not Fastbird93. my heads have been milled over .030, I run thinner headgaskets and the GM847 cam with larger valves. My piston to valve clearance was .085" Typically you want atleast .100 exh and .080 int for valve clearance. You should be fine.
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