Swapped the stock 327 cast iron intake and 2bbl rochester for a Performer and Quadraject setup on an original '67 327 block that I recently rebuilt.
After driving it a bit (maybe 50 miles), I developed a severe intake backfire popping noise, complete with shutter in the gas pedal from the butterflies. Things I have checked and the results:
-Verified timing to 8-10 BDTC with vac advance off.
-Verified vac line connected to ported vac, not straight vac.
-Engine runs, but makes an individual pop backfire to intake, my guess is just one cylinder is popping.
-Intake backfire = too lean, right?
-Used carb cleaner to wet around gaskets without much luck in sealing a gap.
-Went ahead and changed the intake gaskets to Mr. Gasket ultimate sealing type with raised port edges and all.
-Sealed all bolts, intake valley with RTV
-Carb idles at ~800rpm in drive
-Compression checked all cylinders - all within 5-10 psi of each other
-Checked distributor again to verify not 180 off, but engine runs fine with all other cylinders
-Verified correct plug wires to corresponding cylinders.
In reading through previous threads, maybe I have the valve rockers on too tight . . .
What else might I check?