Quadrajet Problem Solving > Quadrajet Parts and Numbers

Newbie with Decoding question

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Cliff Ruggles:
You are lucky in one respect, that carb does not need any modifications to the idle or main airbleeds.  It may need idle tubes enlarged, idle down channel restrictions, and idle bypass air, but no other mod's are needed to the main components when setting it up.

Most likely jets and metering rods will need upgraded as well.  Not sure exactly what recomendations to make without knowing the specifics about the application?.....Cliff

tall455:
Thanks Cliff - thats good news. My car is a 1971 Buick GS convertible. It is heavy - with me in it and 1/2 tank of gas we weigh 4100 pounds. It has a 2.93 posi rear end and TH400 automatic transmission. The torque converter stalls at about 2200 RPM. The engine is a 1973 455, bored .030 over with 8.5 to 1 forged pistons. The intake manifold is stock cast iron. The heads are moderately ported stock heads, stock valves with a 3 angle valve job and "Stage 1 spec" valve springs. The specs on the cam are 230/242 degrees duration, .490/.488 lift, 114 degrees lobe separation. The rocker ratio is stock 1.55 The exhaust system is headers with 2 1/2" dual exhaust and dynomax mufflers. At a track 1000 feet above sea level, I ran a best of 14.1 seconds at 99.5 mph in the quarter mile, shifting at 5400 RPM, but only turning about 3800 RPM through the traps because I do not get to third gear until a few hundred feet from the finish line. Best regards - Robert

Cliff Ruggles:
For the 455 with 8.5 to 1 compression and that much camshaft, it's going to need some idle and off idle fuel, and re-jetted as well.  I'd use the upper end of the 3rd "recipe" in our book. 

I have the correct jets and custom metering rods in stock, and the correct power piston spring as well.

Not much else will be required, aside from a high flow Viton needle/seat assembly, and good accl pump to hold up in ethanol.......Cliff

tall455:
Thanks for the recommendations! I forgot to mention that I am using Crane "High Intensity" fast bleed down lifters. They work similar to Rhoades lifters except they do not bleed down so fast that the lifters "click". They do work well in "taming" the idle.  Have a good 4th of July weekend - I'll call your shop Tuesday and get the proper parts on order. Best regards - Robert

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