The Stovebolt Site Forums The Shop Area Engine Shop Cylinder head exhaust port/ exhaust manifold port?

Not sure what way to go here. I am planning on running a set of 461 g.m. cylinder heads which has a 1.50" round exhaust port. Now, my exhaust manifolds have a stock 1.312" rectangular shape. I could see it being the other around, so what would be my best option here? Get the Die grinder out? Thank you!

To me it looks like the exhaust pressure coming out of the cylinder head would be partially blocked if the exhaust manifold ports are smaller, thus loosing power.. This is the way I bought the cylinder heads with round ports, some 50 years ago..

Yes, you'll need to blend the exhaust manifold ports to match the head ports. Even a relatively abrupt cone shape in the manifold to prevent turbulence as the exhaust gases enter it is better than creating a step. Those round ports are intended to be used on a race-only engine with headers of the same size and shape as the ports. As I've been preaching for years, doing race engine stuff on a street engine makes no sense, and usually ends up with a very temperamental engine which only develops increased power at RPM ranges and road speeds that makes the vehicle a ticket magnet. Cops and judges love hotrodders!
Jerry

Thanks Jerry, out where I live cop's are generally dealing with more serious stuff then us small hotrodders as we generally go up to a 1000 ft. track about 10 miles from here just to have a little fun..

Put four turns and a chert gravel surface, and 20 cars on that track, and you can do some real racing. LOL!
Jerry

Yeah you know Jerry were not to far from where you run that frozen whale up over the Grapevine some time ago.. Were still just a bunch of Ol country farm boys still alive having fun and of course having the Good Lord with us.. Jerry your the Man and I can honestly tell you most will agree. Thanks..