Current GM Q-jet Rules

[oldskool]

Originally Posted by Travis Miller

There is one style Pontiac Q-Jet that has the bullet shaped cluster in the primary venturi with no outer ring. It is only allowed to be used on the SD Pontiac engine which it came on. We have a few racers who still bring us that style Q-Jet to be looked at. Unless they are racing a SD Pontiac, it is not allowed.

I think you are referring to the 455HO engine carb. Some of them came without the outer ring, in '71, I believe. A few were also used on some other engines, besides the 455HO, including a 400. These were discontinued when it was discovered that they were not very street friendly. This is just info I've read. Have never had, or even seen one of these carbs, up close.

http://www.classracer.com/classforum...22&postcount=1

The '73-'74 SD455 engines came with an 800cfm Q-jet, which had a slashed vent tube, and the larger venturi primaries with double booster rings.

These articles contain info on both carbs.

http://www.cliffshighperformance.com...history_2.html

http://www.hotrod.com/articles/hppp-...et-carburetor/

https://www.facebook.com/pg/PontiacT...11336215645409

https://assets.hemmings.com/story_im...00-0.jpg?rev=2

That slashed vent brings up another question, for me. Are slashed vents allowed, on carbs that did not come with a slashed vent ?