Messages

Brand new HEI distributor with new plug wires and plenty of juice to it. Double double checked correct installation and firing order. So I tend to think ignition as OK for the moment. Looking into other possibilities. The exhaust is running rich regardless of mixture screw adjustment. When I get a muffler backfire I get a drop on the vacuum gauge, indication of a sticking valve? need to pull plug wires and see if I can isolate the cylinder that's acting up. Thinking I have multiple problems here.

I have a '69 396 BB engine in a 69 Camaro that I'm working. The engine was totally rebuilt 10 years ago and I installed new rod bearings, rings, mild performance cam, new timing gears, and ground the valves and seats. When the engine was fired up it ran like a fresh motor, not issues. It had a stock points ignition and a 4 barrel Qjet.
The engine then sat for 8 years due to unexpected issues in life. I rebuilt the carb to insure no stale gas/varnish issues. Upgraded to a new HEI distributor and new wires. I insured that the distributor was installed correctly ( #1 at TDC with rotor pointing to #1 tower). Fired it up and the vacuum gauge holds steady around 11 inches. It backfires through mufflers. On acceleration it backfires through the carb and mufflers.  Adjusting the timing does not improve the symptoms. Adjusting the valves did not correct it. Ran a compression test, cylinders came in at 110 psi with minor variance. Cylinder leakage test show no major issues. Any ideas on the root cause?  I suspect sticking valves. Any ideas out there?