i have a 82 f100, and i need a motor, i have a 90 injected 4.9, and a friend said that i could put the head from the 82, on the 90 and it would work, the only thing i need to do is put a electric fuel pump, is this true? thanks

 

can anyone answer my question?

 

I'd imagine it would work. I went the other way with converting an 86 to EFI from an 87 motor.

Adrianspeeder

 

It will fit but it won't work very well. Two reasons

1) The older heads from carbureted engines have a different and larger combustion chamber than the EFI engines. Putting a carby head on an EFI engine will drop your compression ratio from 8.8:1 to approx. 8.3:1. A head from a 240 will also fit and because it has a smaller chamber, approximately the same size as the EFI 300 it will not lower your CR but it will not solve the other problem.

2) The EFI heads have a "fast-burn" design: heavily shrouded intake valves, high quench, etc. All the carby heads, 240 and 300 lack these features. The spark/fuel/RPM curves in your PCM are based on the fast burn EFI head design and will not run well with a carby head

 

hey, thanks for the info, im glad there is guys on here that will take time to answer a question. i guess i will find a good motor to put in my truck., jim

 

You just have to be patient - there just aren't too many 4.9 experts around here.

 

But there are a lot of them at www.fordsix.com