I am purchasing a rebuilt engine for my GN. The machine shop has offered to change the current 4 angle valve opening to either a 5 or 7 angle. Which is better for these cars. Car is mostly stock. Chip, injectors, exhaust, boost dialed up, etc. This engine came out of a GN with Nitrous that ran "high 9s" at a local track. I have talked to others who know the owner. The guy brought it in, the shop tore down the engine, and the guy left town - leaving the engine - rebuilt - ported and polished heads, polished crank and cam, new pistons, etc. The shop owner said it will be all profit as the guy had paid him for work done so he is letting me get it very inexpensively. I am the guy that my "church member Buick loving mechanic" blew it up when he was dialing it in for me while I was in the hospital having surgery. I am so THRILLED to be getting my GN back on the road!!!! Which valve job would be best?:smile:
Valve Angles????
- Thread starter tscruggs
- Start date
- Joined
- May 26, 2001
A 3 angle.:smile:
- Joined
- May 26, 2001
Seats on a stock valve are so narrow, more than a 3 angle job will just beat them down if you step them more, especially for street use on unleaded gas.
- Joined
- May 26, 2001
A good machine shop should be able to easily do a 3 angle job for you.
turbodave231
Moderator
- Joined
- May 24, 2001
I have a little different view on this question.
More than 3 angles should not impact the valve seat durability. The 45 degree sealing surface where the valve face contacts the seat should be the same width regardless of the number of top or throat angles. The additional angles provide a smoother entry and exit from the port to the chamber.
Some of the best and most expensive carbide seat cutter blades (see the Mondello series in the Goodson catalog) have multiple angles and some even have radii instead of angles. In Theory, the extra angles help the air "Make the turn".
In the real world, the only way to know if the additional angles help, is to test on a flow bech before and after.
On stock heads you would be better served by unshouding the bowls under the valve seat, match the port to the gasket and do a good 3 angle job. Compare the a stock head to a Champion ported ............or any other well ported stock head. Work done in this area will provide good results.
More than 3 angles should not impact the valve seat durability. The 45 degree sealing surface where the valve face contacts the seat should be the same width regardless of the number of top or throat angles. The additional angles provide a smoother entry and exit from the port to the chamber.
Some of the best and most expensive carbide seat cutter blades (see the Mondello series in the Goodson catalog) have multiple angles and some even have radii instead of angles. In Theory, the extra angles help the air "Make the turn".
In the real world, the only way to know if the additional angles help, is to test on a flow bech before and after.
On stock heads you would be better served by unshouding the bowls under the valve seat, match the port to the gasket and do a good 3 angle job. Compare the a stock head to a Champion ported ............or any other well ported stock head. Work done in this area will provide good results.
knperformance
knperformance
- Joined
- May 4, 2006
TurboDave is correct, we typically use minimum of 5 angles on all of our heads
on the intake and a full radius on the exhaust. Also depends on type of head
and chamber shape.
on the intake and a full radius on the exhaust. Also depends on type of head
and chamber shape.
These cars are so FUN! This is my second one - the first I bought new 12/87 and have always regretted selling it. I am still learning. I will post after we install the engine next weekend and let everyone know what we went with and how it is running. THANK YOU for your input!!!!! Y'all are AWESOME!
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