How bad do they flow compared to headers? The stock log type ones...... Having a tough time finding headers that I like, manifolds would simplify things but I don't want to give up a bunch of power. Anybody do a dyno comparison between the 2? Factory cast headers are likely out of my price range, may have to build some headers...
406 fe manifolds aren't that bad on price, comparable to good headers, 427 fe manifolds ray on the price, 428 cj manifolds are.good too but you have to have the 16 bolt cj exhaust pattern for them Sent from my SAMSUNG-SM-G870A using The H.A.M.B. mobile app
Might be easier to find the 1966-67 Fairlane/Comet 390GT exhausts than a 428. But still need the 16 bolt heads.
IMHO, price shouldn't be a concern. looks and functionality should be. If you want higher horse power, then anti-up for a set of headers. If you think the cast iron manifolds look great on your ride, then spend whatever it takes to get the set you like. Either way it's a small investment in the big picture. Consider this; a modified engine, (i.e. longer duration cam, ported heads, aftermarket aluminum heads, or even OEM HP heads, bigger CFM carb, higher gear ratio, etc.) should absolutely have tube headers. If you choke a modified engine with stock type cast iron exhaust manifolds, then you waste all the effort and money you spent modifying it. On the other hand, if it's a relatively stock engine, (even the hypo version) then tube headers are generally one of the first things that you change, in order to free up cheap horse power by allowing the engine to breath. That's why guys with modern LS cars change the factory air cleaner to a K&N system. So do you think you want/need tube headers or not? Answer to your question...40 to 75 horse power, depending on what other modifications are made. If you added a bigger carb, but no headers, then you're cheating the carb from making it's full potential of power. As a wise man once said, "Everything must be in harmony Grasshopper." Dave
The FE log style manifolds are a result of a competition to see who could design the worst flowing exhaust manifold on earth. IIRC in Jay Brown's FE book headers were a 30-40 hp gain. Sent from my SM-G930V using The H.A.M.B. mobile app
Those Sanderson headers above(#FF427) are close to what I need, but they are a bit too long with the collectors at oil pan level. I bought a set of stainless shortys off ebay, they will work but the quality isn't the greatest. I kinda knew that the log manifolds sucked.....thanks for making up my mind!
During my years in the header business, Fords showed the biggest gains with headers compared to the factory exhaust, especially any FE with the standard log type manifolds. If you care about getting power out of your Ford, spring for some headers, long tube are best but even the common block hugger should be better than the standard log manifolds. My old F100 with a stock 390 really came alive when I built a set of 1 7/8" x 35"L headers into a 2 1/2" exhaust system.
I have had a few FEs , the log manifolds are the worst OEM manifold I think I have ever seen . The 427 style headers must be close to 75lb for the pair