Modern valves for an out of production engine


I am gathering parts to build a stroked Rover 4.0. I have a set of Buick 300 heads I want to use, but would like to install a set of larger valves. I intend to replace the seats to match what ever valve I find to run. What I would like to hear is from others that have put larger valves in a Buick 300. What valve did you choose, and how did they work? I am willing to cut to length the stems, or even go to larger guides if necessary. So I ask, what did you do and how did it go? Thanks!


Active Member
Larry, I took the head to my STRAIGHT EIGHT to a performance machine shop and asked them to do their thing. They did. I have no idea what was used. They have access to EVERYTHING.

A good place to start your search is the SBI e-catalog found here:
I do notice that it does not show a listing for the intakes, which means you will have to measure the intake valve diameter. The stem and overall length will be similar to the exhaust which is listed as an 11/32" stem (good same as sbc = cheap), length 4.643 (not so good sbc is 4.923).

At a quick look, I see the Ford Ranger uses almost the same exhaust with a 0.270" stem. The intake is 1.661

Or, better, look at 1986 Buick Century. 11/32" stems 4.649" length, 1.5" exhaust, 1.72 intake.