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Author Topic:   Valve Seals
chief4car
Dirt Full Roller

Total posts: 56
posted July 10, 2002 09:40 PM
Just recently we had to have all of the valves replaced in our heads (motor trouble). The heads are DART Iron Eagles. The machine shop called me and asked if I wanted new valve seals put back on the heads (old ones no good after replacing valves) I told him yeah put them back on. He asked me did the seals come on the heads when I bought them. I told him they are just as I bought them.

He then tells me that most of the racers that bring heads to him dont run valve seals, which is why he is asking me. I asked why they dont run them. He says the guides wear out faster.

My question, is this right. Should the heads be run with or without the valve seals and what are the pros and cons of each way.

Sorry about the length,

Jim Cleaver Jr
Cleaver Racing Inc

CUSTOMPERFORMANCE
Dirt Forum Champ
Total posts: 639
posted July 10, 2002 10:12 PM
i RUN MINE WIHTOUT SEALS AS DOES MY MACHINE SHOP RECCOMEND THIS ON RACING ENGINES, THE GUIDES NEED ALL THE OIL THEY CAN GET IF YOU RUN SEALS THEY GET OIL BUT NOT MUCH. THEY WILL WEAR OUT FASTER WITH SEALS.

chief4car
Dirt Full Roller

Total posts: 56
posted July 10, 2002 10:18 PM
If you run without the seals does this or could this cause oil to leak into the chambers, and cause other unwanted problems

Thanks
Jim

Monster
Dirt Maniac

Total posts: 135
posted July 10, 2002 10:37 PM
I can't recall one of the racers that have brought their heads to me to port, machine, or otherwise set up that has had a specific opinion on that. They have said: 'Set 'em up', and that's what I do. Bronze guides, honed(not reamed, broached, or knurled!) to fit each individual valve, a wiping type seal on the intake to keep oil out of the chamber and to keep as much crud from forming on the back of the intake valve as possible. On the exhaust, most of the time nothing is used, rarely I will put an umbrella type seal on. My opinion is it is of the utmost importance to keep oil out of the chamber, cause oil reduces the octane of the fuel, which can lead to very bad things. A seal will let a measured amount of oil through, and control the rest.Oil control is a good thing to maintain. Valve guide wear has not been an issue with heads done this way. They can and have lasted for 3 seasons if the valve train is set up correctly. Other ways of finishing the guides may not wear as good. A racer would have to argue long and hard with me if he wanted no seals at all. High performance cylinder head work has very little in common with everyday automotive machine shop jobs.

sdhnc29
Dirt Freak

Total posts: 467
posted July 10, 2002 11:13 PM
Jim ,
Once again I'd have to agree with monster on this subject . Valve guide wear has nothing to do with the seals that are used . 99.9 percent of the time , premature guide failure is caused by valve train geometry problem's , and NOT valve stem seal's !!

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

chief4car
Dirt Full Roller

Total posts: 56
posted July 11, 2002 09:31 AM
Thanks guys,

You confirmed my opinions.

Thanks
Jim Cleaver

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