Bigger Vaules!!!

Lebedin8654 · Jan 28, 2008

I have gt40 heads, is it worth up grading the vavles to 1.90 intake and 1.60 exhaust? and can you just switch the valves or do you have to get a machine shop to do it, if so whats a good price? :dunno:
Thanks

Nacho · Jan 28, 2008

If you have to ask, then you can't do it. Better to take it to a machine shop BUT, I wouldn't recommend it. A nice port work will do the trick.

Lebedin8654 · Jan 30, 2008

i have done port jobs and spring up grades what i was wondering is when you switch the valves out with bigger ones do you have to do a valve job or can you just switch them in and out?

Mr. OAM · Jan 30, 2008

If you just put bigger valves in the head but the seat area and the opening remains the same diameter what gain would you get?

Larger valves are installed by machining the pockets and seats larger in diameter so that more flow is gained. Its not a matter of just closing up the same hole with a valve that is now too large. The pocket diameter has to be larger as well as the seat. The idea is to make a larger hole in the head for flow. In doing this you have to be careful with the affect it has. Velocity can be reduced and low end torque could suffer, as an example depending on how much of a difference in cross section is made.

Steve