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I took my stock exhaust manifolds off my 81 f250 351m and i got the new passenger header on but with the driver side its hitting the subframe where the motor mounts are. So i really dont k ow what to do at this point a buddy of mine said cut the subframe but i dont want to mess the the structural integrity but really dont see any other way. Here is what the new headers look like
Cutting the frame is not common for headers you buy that are supposed to fit. I have put several sets in different vehicles, and while I have had to tweak the header here and there, I have never had to cut any brackets or frame pieces. They will tell you in the instructions to look at your motor mounts if you have a serious fit problem.
Everyone here knows how I feel about long tube headers on these trucks anyway. Your headaches are just beginning, you have the rest of the system to hook up and that's not easy to do and make it look good and be able to get to the transmisson pan to service it. I would take them back.
Dave F., you forgot the big one header leaks!
Both at the heads and collectors.
Dave ----
I have had header leak problems with the old style headers. With the newer style and the "o-ring" style flange that bolts to the heads, they seem to have conquered the leaking header problem. Their "o-ring" is just a big fat weld on the flange at each tube, and then they grind the weld flat across all the flanges.
Actually the headers I have bought for these style trucks fit pretty good as far as the engine compartment went. It's the underneath hook-up I didn't like. And I always bought the cheaper brands, and they usually only lasted about 5 years before they rusted through. I drive my trucks in the winter, in the snow and salt.
My high-dollar L&L headers sit on the driver's side engine perch. That means there's lots of engine vibration introduced into the frame, and there's a clang when you shift gears rapidly as the engine returns to the "rest" position. I'm not at all impressed, and question the use of long-tube headers in these trucks.
My high-dollar L&L headers sit on the driver's side engine perch. That means there's lots of engine vibration introduced into the frame, and there's a clang when you shift gears rapidly as the engine returns to the "rest" position. I'm not at all impressed, and question the use of long-tube headers in these trucks.
IIRC the headers I used came from a similar-year F250 2WD with a 351M, it was apparently some enthusiast's project truck in really nice condition with an MSD ignition + other goodies but that somehow ended up in the junk yard, this was close to 10 years ago by now.
