- Location
- Rollins Lake, CA
So I have a 1990 superjet with a 61x single carb bottom that I grinded out to accept some 64U 760 cylinders. Ive been running it like with stock 61x exhaust for years now and its been ok, but Im going for more power and I have a full coffman exhaust off a 650 and want to put it on the 760. From the research I have done, it seems like I have an early 650 coffman manifold, the ports are small and narrow. Even if I got a 701 manifold I think I will still have to get it ported to match. I compared the exhaust gaskets from the 61x stock exhaust to the 760 exhaust gasket and 760 is still bigger. Just trying to see if anyone has done this, and what my options would be. Will I be able to have the 650 manifold ported to match the 760 cylinder? Besides the ports, is the rest of the 650 coffman MANIFOLD the same size internally as the 701, or is it bigger? Thanks in advance