do you also grind the seat at three angles and do all three angles seat or touch when the valve is closed and provide a better sealing surface or are the angles cut away from each other just to provide better air flow when the valve is open. please explain in the best detail you know try to weigh spend the extra expense when building my new motor
2007-01-08 11:57:01 · 6 answers · asked by Daniel L 1 in Cars & Transportation ➔ Maintenance & Repairs
The seat has to be ground and finished to match all the valve angles that meet the surface of the seat. The machine shop I was at did 3 angle valve jobs on just about any cast iron and some aluminum heads. Its pretty much standard now. The newer equipment are providing service that was extra years ago. I suggest you go in person and talk to a local engine machine shop to get your answers.
2007-01-08 12:05:28 · answer #1 · answered by Anonymous · 0⤊ 0⤋
No, not all three angles touch the valve.
No, it doesn't really have anything to do with airflow.
The seat is ground at 30, 46, and 60 degree angles while the valve is cut at 45. The valve seals between the 30 and 46 degree part of the seat. The thickness of the 46 degree part on the seat creates a valve seat pressure. The wider it is the less pressure, the thinner it is, the more pressure. This 1 angle difference also allows the valve to smush carbon deposits and still make a seal. The intake valve seat will usuall have the 46 degree part about the width of a dime, and the exhaust about the width of a nickel. The intake is of larger diameter and would need a thinner contact area to generate the same pressure as the exhaust.
Most shops do the 3 angle valve jobs and I wouldn't recommend any different. The sealing is better and they last longer. There are two ways that they can do it. They can use a cutter or a grinder.
Hopefully I have explained this well enough for you. I could do so much better with drawing some pictures.
2007-01-08 16:00:18 · answer #2 · answered by adventurouscouchpotatofun 2 · 0⤊ 0⤋
Everyone seems to be of the same opinion. Multiple angles cut into the valve promote better flow. I would consider a 3 angle job to be the minimum for a mild performance motor. I think the valve seat needs only one angle but you would want to smooth any sharp edges that the intake charge would pass through. This would be pretty standard stuff at any good machine shop and should not cost a bunch extra. If this is just a stock rebuild I don't think you would see enough benefit to justify a lot of extra money. Hope this helps.
2007-01-08 13:41:56 · answer #3 · answered by Jason z 2 · 0⤊ 0⤋
I used to do 3 angle valve jobs. It's mainly to reduce the turbulence of the mixture as it goes over the seats and promote better flow. It takes some care to get the middle angle to come out in the middle of the valve face, so it has to be a good shop. It makes a pretty small difference in engine performance. It's just one of the dozen little tricks to engine rebuilding that all add up if you do them right.
2007-01-08 13:05:39 · answer #4 · answered by Nomadd 7 · 0⤊ 0⤋
The seat is grinded, but not at 3 angles. It seats fine. The 3 angles only provide better air flow. Depending on how much you're paying for it, its worth it.
2007-01-08 12:02:17 · answer #5 · answered by blacksrt4acr 2 · 0⤊ 0⤋
better flow from the more gradual turn. My impression was that one or the other (probaly the seat) had 2 angles cut. It's also supposed to seal better and run cooler.
2007-01-08 12:05:40 · answer #6 · answered by popeyethesadist 5 · 0⤊ 0⤋