I just swapped the engine of my 1994 G20 van with an older engine from a pick-up truck and would like some insight on timing settings. The G20 engine I took out had an EFI 305, and the label shows the timing to be set at 0 degrees. The engine I installed is a 350 and it comes from a carburated 1984 C20, its timing was 6 degrees BTDC. I installed the engine using the EFI intake manifold and injectors. I set the timing at 0 degrees and it starts and idles, but not smoothly, it also backfires when quickly letting go of the accelerator. Should the timing be set as per old truck specs even though it wasn't EFI?

Thanks

 

Backfire is timing. I'd not think 6 % would make alot of difference, but it's easy enough to play with.