JayRay

I have been reading in 1975 GM Modified the Qjet and "De-Tuned" them. Is there any advantage to be gained running the earlier model QJet on a Later Model (1977 L-48 Stock 350)?

I have not been able to find out exactly what they mean by "De-Tuned"

I am about to rebuild my carb and used QJets are cheap so I figured if I am going to rebuild one I might as well rebuild one that will get as much gain as possible. Any one know advantages to jumping up or down to another Qjet part number?

This is a Friday Saturday Car and Not a Daily Driver. No Track use but occasional winding mountain roads and highway.

MelWff

get the current paper from Lars below is an older version and it explains the differences

http://www.digitalcorvettes.com/foru...ad.php?t=88376

OMF

I think the biggest advantage of a later model (post'75) Qjet is the APT (adjustable part throttle) feature. This allows you to easily tune part throttle AFR.
The earlier models didn't have this feature.

jim2527

Most will say the later ones are better due to the APT as previously mentioned.

In a certain sense they are 'detuned' because they're 'rejetted' for lower horsepower engines. No big deal, just rejet back up.