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I can tell you a brand that I would never get again - Clifford!
The flange warped after 13,000 miles. After 8 phone calls to Clifford to get advice, I took them to a machine shop to have them trued. Clifford's best advice was to lay the flange on a flat, concrete floor and beat with a shop hammer until it was straight. I even asked them what they would charge me to true them in their shop (since they manufacture them there), but they basically refused. It also took them 28 days to get a manifold gasket to me, but only one day to charge my credit card. Needless to say, I wouldn't recommend them based on their customer service.
For reliability I don't think you can beat the dual cast iron exhaust manifolds of the EFI 300s. If you already have EFI, you could pull the manifolds and have them opened up a bit and line up the ports for better flow.
INLINE SIX POWER! '95 F150 XL
300 Cubic Inches of Low RPM Truck Torque! And twin-I-beams too!
"Drive a stick young man! There'll be time for automatics when you're old and unable."
What kind of intake are you running? I have a clifford intake the thickness of the flange is not the same as the header flange..What did you do to get yours to seal up good? I am thinking machining a step washer. Right now I jsut ground one side of the washer down further. IS the Offenhauser Intake have a thinner flange?
I just took my headers of and put them on my BIG MISTAKE pile. I have an offenhouser intake and dynojunk headers. the header flange and the intake flange are different thicknesses and mine will not seal up eather. I went back to the stock exhaust manifold but ported it out a little with a die grinder. No prodlems.
Forget headers!!!!!!
Hmmm interesting so with the Offy intake you can use the stock manifold? That is very good to know!!!! Must make installing them very easy!!! No more hidden bolts? Can you get all bolts with a socket?
I used the pacesetter header offy intake with the stock bolts and washers. Yes you have to wrench some but you do on v8s also. The thicknesses are pretty close. I always use copper high temp rtv on header gaskets and you must spend some time lining these up. The thing is headers require some matinence on any engine just the bolt/washer/flange setup takes more. I look at it this way I replaced 2 manifold gaskets on the stock setup and they ended up leaking also. So at least the header gives some power and nice noise for the aggravation.
[updated:LAST EDITED ON 31-Aug-02 AT 12:15 PM (EST)]after porting the stock exhaust manafold and puting it all back together with the exhaaust from one of the headers it seems that i didnot loose any power over the headers. Still have to wrench on a couple of the bolts but no leaks after for three months now.