Cliff's Quadrajet Parts and Rebuild Kits

General Category => Quadrajet Carb Talk and Tips => Topic started by: 70GS455 on September 20, 2017, 01:59:56 PM

Title: Supporting high hp - thin down the pri and sec shafts?
Post by: 70GS455 on September 20, 2017, 01:59:56 PM

Is it advisable when supporting high hp (say 600) to thin down the primary and secondary throttle shafts or choke flap shaft (street/strip)?  I've seen this done on throttle body shafts to get a few more cfm by reducing shaft cross section.  The downside is if you get a backfire strong enough to break the shaft, you get instant WOT

Title: Re: Supporting high hp - thin down the pri and sec shafts?
Post by: Frank400 on September 20, 2017, 10:37:23 PM

  I really don't think it's needed.  Cliff's own carb (on a 600 HP Pontiac motor) is physically 100% untouched except for correct calibration.

  Also, many Stock and Super Stock racers are deep into the 9 sec. range without any physical mods.

  I wouldn't do it if it was me.

Title: Re: Supporting high hp - thin down the pri and sec shafts?
Post by: Cliff Ruggles on September 21, 2017, 04:20:18 AM

Complete waste of time on a Q-jet, IMHO. 

We have Q-jets on high HP and Super Stock applications well into the 9's w/o touching the shafts, and many of them are the smaller "750" cfm castings!......Cliff