I have heard of issues arising with the thickness of the flanges being different between the intake and exhaust manifolds, causing problems with leakage because the bridge clamps don't hold the parts tight to the cylinder head. Also, the quality of the offshore made "Fenton" clones is poor at best, nothing like the USA made manifolds from the 1950s and 60s. Using coolant to "heat" the Offy manifold is a lost cause- - - -it's cold when the manifold desperately needs exhaust heat- - - - -during warmup. It's possible to plumb exhaust gas heat to the area at the center of the Offy intake manifold with some creative plumbing- - - -right where there isn't a carburetor to benefit from it. Why don't the "It worked fine for me" comments ever include dyno run figures to back up their claims? (Maybe because there aren't any?) "Your mileage may vary!" My dyno tests usually documented no improvement- - - -or a power loss everywhere except wide open- - - -high RPM operation.
Jerry
