I'm running a '72' 300 six, all stock, in an F250 Special. This truck has been a real workhorse for 162000 miles. I'm the second owner and the first was my father. I rebuilt the engine in 1992 at 135000 miles after it started smoking. It ran like new. Now however, it starts hard, won't run right till it's warm, has little pulling power, lugs on hills, doesn't accelerate, and shifts hard, etc. I've had to change the exhaust manifold three times due to warping. Stock manifolds. Can't find them at the wrecking yards anymore.

Compression is good on all cylinders, although I can't remember the numbers. So is the spark. Can't find a vacuum leak, but that's what it acts like.

Will the split manifold for the EFI engines bolt on? What kind of header would help? I tried to put a standard header on several years ago and it wouldn't fit due to the one ton frame's extra cross member right where the header was supposed to hook up to the exhaust.

Could it be the Carb? It's a stock Carter YF, and I haven't seen any posts telling me I can bolt on any other Carb, except a Rochester (NO THANKS!) without modding or changing the intake. I bought a new one years ago, and it ran horrible, so I put the original back on, and I've rebuilt it at least twice since then.

Regarding the Intake. Is there a replacement with better airflow that is inexpensive? I've looked at Clifford, Offy and others and they all want over $300 for an intake, same for the exhaust. For that, I could buy another engine from the wrecking yard. Regarding that, could I switch over to EFI?

How about aftermarket Electronic Ignition? I found Pertronix, Mallory and Crain conversion kits and I don't know anything about them. I also found instructions for putting later model EI on this engine. Which way should I go?

Off the subject, why did they never make this engine into a diesel? It's certainly built heavy enough.