Howdy all,

Joined the forum to try and get some help with my first engine swap. I have a 1968 F-100 with a carbed 360 and C4 auto-trans. My rings are worn and valve seals and it's either rebuild or swap. I'm looking to swap it out for a 300 I6 due to the slightly better gas mileage and famed durability. Found an EFI running 300 out of an '83 F-150 and am wondering about which route to go. I have limited time to do this and want the end result to be a truck that runs decent and doesn't burn a quart of oil everyday.

I have a couple questions...

Is there anything more involved in converting the EFI 300 to a carbed setup than a new intake, pump, and carb? Also, should the C4 transmission just bolt on. Read about some difference in balancers.

Would it be easier to keep the EFI setup and wire it in? Is there a way to do the fuel return line that doesn't involve a different tank. I only have an in-cab tank.

The truck in bone stock. I have mechanic experience but no swaps. How long should this take?

Thanks for reading!

 

First thing is that you have an FE engine (352, 360, 390...) coupled to a C-6 trans, not a C-4. To use a Big Six (240, 300) you would have to find a Small Block V-8 (302, 351W) pattern C-6 to fit in place with no changes. A C-4 is a shorter trans so will have to use a longer driveshaft. If this is a 2wd, then all you have to do is slide the engine stands to the next hole with the required engine motor mounts. If 4wd, the engine mounting is different between FE and the Sixes. IIRC EFI didn't happen until 87 so that EFI 300 was swapped in, or it has been swapped with a carb.

 

Thanks for your help! Sounds like I need a c6 with a windsor bolt pattern. Any suggestions on adapters or should I try and find another transmission? What would be the best to look for that would be an a straight forward bolt on?
It's a 2wd auto.