The Stovebolt Site Forums The Shop Area Engine Shop Exhaust manifold

Does anyone know which performs better the GM stock split exhaust manifold from the blue flame 6 (corvette 235) or the fenton split exhaust manifold?

The Corvette has provisions for exhaust heat to the intake manifold, so would be better for all applications with exhaust heated intakes. With non-exhaust heated intakes, it wouldn't matter.

It's hard to get or give numbers, but by just looking at your two choices I would say that the fentons flow better. BUT, I would not give up the exhaust heat to the intake manifold for a street driver. Corvette duel exhaust manifold is REAL hard to find and they usually go for over $600+.
I would go for the "Kansas Kustoms" split. http://www.kansaskustoms.net/

Old fart, thanks for the info I purchased the manifold along with a lot of 235 parts including an offenhauser 2X1 with carbs. I will probly run the corvette manifold for the carb pre heat.

The ultimate is the original Fenton with the heat box on the back header that bolts up to the intake. With that, you get the heat you need plus the TRUE split exhaust which isolates the front header exhaust from the back header exhaust and gives you the unequaled sound of the Chevy inline six. Kansas Customs can achieve the same TRUE split, but you won't get the "flow" of the Fenton headers.

Joe

This has been brought up a few times. If this vehicle is to be driven a lot, it might be worth considering that exhaust heat in an ALUMINUM intake will cause it to "carbonize" and fail eventually. Water heat is cleaner and will result in a more consistent temp resulting in better mpg and a longer life for your intake. A cast iron intake is a better material for exhaust heat. Or so I've been told.

Rougie ~ If you already have a corvette exhaust for your 235 then use it, use it, use it. Just make sure that the heat flapper works on it. You can still get a new spring for it.
You are one of the lucky ones. Use the Offenhauser 2x1 with it also. The debate on water heat over the exhaust heat has been an on-going thing. If it were me I would definitly use your corvette exhaust. But here is a tip if you don't, if you or anybody else use the Offenhauser intake with water heat. Remove the two steel plugs on the bottom of the intake and weld two aluminum slugs in their place. Otherwise you will have water dripping out the bottom of your intake. The two steel plugs that come in the bottom of the Offy intake are not water tight. Put a pair of Stromberg carbs on it and it will run like a dream. Good luck.

Steel plugs?
Just receceived a new Offenhauser. I noticed what appeared to be a bit of grinding on the bottom in two spots. I'm assuming this is where the steel plugs are. Were these inserted as jig mount fillers in the casting process? Now why would Offenhauser put steel into their intake. I'd like to call them on that.
Strombergs huh?
What year(s)? Off a 216? Tom Langdon of Stovebolt said to go after a 'matched' set of Carter W1's of the 47-50 vintages. But would have to elongate mounting holes on carb flange to accomendate pattern on intake. Or vice versa.