I can not get my 390 Ford engine to "hit" on cylinders 2, 3, 5, and 8. The engine has a new cam, lifters, heads rebuilt with new valves, seats, and guides. The vacuum is only about 10 at idle and the needle shakes. Compression on all cylinders is about 115. I have tried the following: Switched spark plugs from firing cylinders to those not hitting, new plug wires, new spark plugs, new points, condenser, coil,and rotor, switched distributors, switched carburetors (4 barrel Edlebrock to 4 barrel Holly and back) , watched the rocker arms move while running the engine with the valve covers off. I have jumped across the resistor momentarily with no change, Voltage at the coil is around 11 without the jumper (power going through the resistor). The valves seem to be seating OK, I can turn the push rods with the lifter on the low part of the cam and there is no "play" with the engine running. I can't measure the valve lift but it looks OK idling, all rocker arms seem to have the same travel. When I first started the engine after the rebuild (rings, heads rebuilt, cam, lifters, timing chain and gears). The engine seemed to run OK and the vacuum was at about 17 at idle and steady. After driving about a mile the four cylinders no longer hit.

I have also hooked the plug wire from a non-hitting cylinder to a spark plug laying on the engine and the spark looks fine. Timing is at 6 BTDC. I have hooked a timing light to each plug wire and the flash is even (consistent)in all cases.

The engine ran poorly prior to the overall and runs about the same now. Sometimes it backfires back through the carbureator as if it is too lean. I have a manual choke and apply the choke does not improve how the engine runs. I do need to choke it while the engine is cold but not after warming up past 140 degrees.

I give up!! Can someone give me some help?

 

There is a better forum for your questions, you need to scroll down to the forum titled FE & FT Big Block V8. There are lots of guys there that know plenty about the 390 V8. Give it a try.

 

Thanks, I will give it a try