01-01-2003, 02:35 AM
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CC Member
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Join Date: Sep 2002
Location: Auburn Wa,
Posts: 15
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Not Ranked
There's another thing alot of peaple don't realize is that the size of the valve has very little to do with it. A CJ valve doesn't work better because it is .04 or .05 bigger in diameter, it works better because of its shape.
The CJ intake valve is flat a hell on its back side and it unclogs the port at low lift and work really well with the 30 degree valve seat.
Makes for really nice low lift flow numbers. In a high horsepower 390 I would still use the CJ valves but I would switch to a 45 degree seat for a higher lift cam. With a bigger camshaft, you actually want to kill a little bit of low lift flow and the 45 degree seat will do that and will shift the flow numbers more to the high end.
Its way more important to have a properly shaped valve than it is to have the very largest valve you can get. I wouldn't give you a squirt of pee for a stock medium riser valve, they have almost a tulip shape and they wont flow as well as a nail head shape (flat) valve.
The exhaust port is another matter ( at least on my edelbrocks) they love a tulip shape valve with as much as a 30 degree angle on the back side.
Just a thought
Dale
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