[QUOTE=zippy;6624488]So, my 455HO (470cid) runs great, get about 15mpg when drive easy. But when hard accel, say from 30mph, Pull out pass someone, WOT itll starve for fuel after a second. Then kinda come back, If I ease off a little, she fine.
remove the secondary hanger and rods. chuck the rods up in a drill, spin and file them down to at least .040" on the tips- a long taper. reinstall rods with hanger into the qjet. Then push the secondaries fully open, measure from the top of the carb nearby, to the top hook of each secondary rod. bend the hanger arms (not the rods themselves) so that dimension is 21/64" from top of carb at wide open- this will be the same dimension as the richest "B" hanger of which in 45 years, I've only seen and obtained ONE. start car, happy motoring.
btw this entire procedure is in Pete McCarthy's first SuperStock book in the Qjet section. you can file them to .040" for starters, but if need be even to .030" tips. Pete Mc. also used rods with only .018" tips on his SS class cars. you can make .020", .030", and .040" tips from rich junk rods from other vehicles, use them as cores to file new rods from. then tune as need be to the engines needs.
I'll add one trick found myself recently - my friend's 1972 455 w/7M5 heads had an aftermarket universal electric choke bolted onto it by previous owner, and the dashpot pulloff vacuum pot to control secondaries was completely missing. I cranked up the tension on secondaries from 1/2 turn of tension on the small spring, to 3/4" tension. also filed the rods to .040" - and adjusted the secondary hanger to 21/64" at WOT. the car is now a rocket- my point being you really don't even need the dashpot If the rods are rich enough to make the transition. this is only with a Pontiac Qjet with the square cutouts in front of secondary air valves, and big fuel pullover fuel passages in top front of secondaries on lid.
HAPPY MOTORING
Last edited by GTO-relic; 07-18-2026 at 09:18 AM.
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