Complicated problems....1989 f350 460
 

I tried to put a 1985 new short block into a 1989. The heads from the 85 wouldn't fit the newer89. The older was carved and newer was fuel injected.

So we put the newer heads on the old block. But now timing is an issue. When you set the timing with a light it doesn't run right. But one extra complication is that the 85 had an RV cam in it.

I manually reset the timing and with a shot of ether it starts and runs but you have to feather the peddle to keep it running. It will also not reach the upper Rpms without bogging out.

I have changed the coil, the distributor, the timing chain, the plugs, cap rotor, wires,throttle position sensor, coil,fuel pumps front and rear,fuel filter, battery. All with very little effect.

Cylinder checks 135-160 on all cylinders, 40 lbs on the fuel rails, stethoscopes the injectors and all function. There is very strong spark.

I have reached my limit anyone else have any ideas?
Cant find vacuum leaks but vacuum lines may not be right...connections? New computer as well.

Better luck in the appropriate section.

@redford please move, thanks.

Moved to 1987-1996 forum.

Though you may have other issues, right off the bat, the 85 uses a different timing chain than the EFI trucks, and the cam may not be compatible with early EEC speed density.

The carb 460 cam timing is 8* retarded. You may be able to fix this by putting an EFI timing set on it.

Also keep in mind you're losing a lot of compression. The carb shortblock block barely scrapes 8:1 compression, while the EFI blocks are around 8.5:1.