look at post # 117 of this thread http://www.alfabb.com/bb/forums/spider-1966-up/29640-msierts-black-spider-project.htmlcast iron manifolds can be as good as tube headers
Headers make sense only if replacing the entire exhaust system with a performance one, such as Magnaflow. Otherwise save your ducats for something more meaningful...
In the state of Kommiefornia, modifying emmissions system including exhaust will likely garnish a "fail" at the next smog inspection. Hence I have only considered doing these type of mods on my pre-76 cars ( cut off YM for smog exemption). Some have resorted to installing earlier S2 OE manifolds on cars subject to smog to gain few hp and some bottom torque without tipping off authorities. Again, without making serious mods to the engine (incl chucking the emmissions mumbo jumbo) and the rest of the exhaust, earlier OE manifolds would be a better option - cheaper and easier to install.that's not strictly true. if the exhaust manifolds are badly done than there is a substantial gain to be had in changing them regardless of what the rest of the system looks like ( on any car ) . as example, my 79 had the iron smog manifold that was terrible and I changed out for the early stock cast " header" system and it woke the motor right up. if I hadn't been able to source an early set I would have done headers of some sort . on this later car that this guy has, I don't know what his stock iron manifold looks like or if its any good or not. if its bad like my 79 was then he will get some meaningful benefit doing something else. if its decent like the early cast headers and he does nothing else to the motor then headers will be a lot more trouble than they are worth as others have rightly observed.
HP peak at 7300, torque peak at 5700.Ed, what RPM was the peak HP at?
just for clarity ... the data came from the sports 2000 cars ( 2l ohc motors ) and other 2l motors in various trim from 150 to 190 hp . not the formula ford 1600 cc pushrod motors that made much less and used a 2" pipe.HP peak at 7300, torque peak at 5700.
I have been inspired and influenced by this project but my motor is not built to survive at such high rpm. Stevesxm in particular advised me that the 2.5" system used in Murray's car was designed for high rpm power and as a result my new system is 2.25". That is the same diameter used by Alfaholics in their system and the same that Steve used on his championship winning formula Ford racers. I will not know for sure where my peak power is until I get back to the dyno but I expect that it will be around 6500.