Re: where to look next?very sluggish 390
I would start with getting some real numbers and more info
- What is initial timing, total timing and what rpm does total come in at. Aftermarket FE distributors are notorious for slow curves
- What is the cranking compression, best with all plugs out and carb wide open. My thought here is you may have accidentally misaligned the gears and retarded the cam
- Which voodoo cam is in it?
- Did you check pushrod length when you swapped the cam in? or was the cam in it in the last vehicle? 390s have multiple pushrod lengths from the factory and many cam kits use SBF lifters which can change preload
- Any chance you have any wires crossed?
- Can you open the secondaries by hand? Engine off, hold throttle wide open from drivers side linkage with left hand, with right hand, grab small secondary linkage and see if it will turn. You will see how the little link bar gets out of the way as you move the throttle.
The coil swap stuff may be a red herring, however, running a coil that says it needs a resistor can hurt the distributor, not the coil. When the coil says that, it is telling you it's got low resistance, and as the field collapses, it can spike the distributor through the trigger wire.
My initial guesses are
- Distributor advance is stuck for some reason
- Timing is off due to slipped balancer or incompatible pointer / balancer
- Bad vacuum leak as discussed
- Cam not degreed properly if new cam
Just generating ideas
70 Sportsroof, 427 FE/489 cid, TKO-600, 31 spline 4.10, A/C. modified Mass-flo EFI/reprogrammed A9L/CnC ported Victor.
Last edited by My427stang; 12-19-2018 at 04:12 AM.