Ford truck engine swap issues

keel

Active Member
Aug 23, 2020
208
73
38
Seattle, Wa
I have a 1979 Ford E-150 that came factory with a 351W and a C6. Long story short, the factory engine had about 200k miles on it and gave up the ghost so I swapped in a roller cam 302 out of a 1996 Explorer. Stole the GT40 heads and intake off of that for my Fox and now the E-150 has an Explorer shortblock with E7 heads, still carbureted. Bolted up to the transmission and converter no problem and drives good for the most part. (Put about 1000 miles on it this year.)

Engine seems to run great but has some issues delivering the power at low speeds and RPMs. The first issue is that the transmission shifts really early when trying to accelerate and drags the engine RPM down too much to make any amount of power. I end up just manually shifting it if I need to accelerate quickly like getting on the highway. Once the engine has some speed it feels/sounds good.

Second issue is the engine struggles to get off the line quickly from a stop, especially going up hills. It feels like the converter is stalling at too low of an RPM and lugging the engine. Unfortunately I don't have a tach on the stock cluster so it's hard to tell how quickly the motor is spinning when this is happening. Should I have swapped in a higher stall speed converter when I swapped the motor? The 351W probably did have more low end grunt.

Anyway, if anyone can chip in and offer some advice on how to fix either of those issues that would be great. It's hard for me to tell if it is an engine problem or trans/converter problem.