Thread: swap 3.5->3.9

Originally Posted by cdbanks

Hi All,
I am going to soon (hopefully) be swapping my 3.5 V8 for a 3.9 V8.
I was just wondering what would i actually need to make the swap work.
Will i need the fuel injection system out of the 3.9 or can i keep the old 3.5 efi?
Do i need the wiring looms or is it a straight swap?

I really just need info at the moment so any advice would be great.

(i did have a look for a thread that covered this but i couldnt see anything)

You really need to be more precise about which year 3.9. The early 3.9 (pre '94) uses much the same front as the 3.5. Afterwards the front is all different (serpentine drive belt) and requires some fiddling to run the old front cover. The 3.5 ECU will run on the 3.9 using the old inlet manifold, otherwise you would have to fit the complete EFI off the 3.9 vehicle.

Originally Posted by bee utey

You really need to be more precise about which year 3.9..

Sorry about that, i was trying to keep it as broard as possible.
At the moment it looks like it will probably be a late model D1 engine.

Also My bus is a 1986 RRC running the original 3.5 v8 efi.

I did this swap about a year ago and I am sure I put up a thread or two about it.