Re: Valve Job Question
[Re: GI Moparman]
#1560863
01/08/14 05:51 PM
01/08/14 05:51 PM
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Joined: Jul 2010
Posts: 2,091 Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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Quote:
So if I'm understanding it correctly, go 080 on intake and 100 on exhaust. I'm looking for making it live on the street. To much money in this thing to go for every hp.
This whole scenario based only on the width of the seat contact area is misleading at best IMO. The width is important, but seat concentricity, valve concentricity and the location where that 45 degree angle intersects the valve is way more important than just the width. There's no reason a .060 wide seat won't live a long life on a high performance street engine as long as the location and concentricity are what they should be. Old worn out valve grinders, worn out seat/guide machines or stones and holders and even hurried machinists would be your worst enemy. good equipment and attention to detail will net great results and great longevity. I've used .040 wide seats on street/strip engines and we don't have any problems with longevity. Your basic 250 HP grocery getter would get a wide 45 angle and last 100,000 miles, a .060 seat done right will live as long as the rest of a good performance build if done right. If in doubt, use some ultra fine lapping compound and only two or three twists of the stick and then look to see the where the gray line is located on the valve and if it goes all the way around the seat at the same width. If it does, you're fine, if it doesn't, have them fix it so it does.
machine shop owner and engine builder
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Re: Valve Job Question
[Re: 383man]
#1560867
01/13/14 12:14 AM
01/13/14 12:14 AM
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Joined: Jan 2003
Posts: 14,539 So. Burlington, Vt.
fast68plymouth
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 14,539
So. Burlington, Vt.
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as two points of reference.....
i remember being in Bartons shop many years ago(late-80's) when he was still up in the Montreal area, and saw some SS/AA heads he was working on there. the intake valve seats were just a very, very thin pencil line.....probably around .015" wide at most, right on the very edge of the valve.
on the other end of the spectrum, that old SBC Pro Stock engine book by Grumpy Jenkins specified the intake seat width to be .100" wide......and that was for a true max effort application.
so whats the right width seat??? its just another example of the many, many things that are engine related that fall into the "it depends" catagory.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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