Current GM Q-jet Rules

oldskool · 02-26-2017, 06:30 PM

Please excuse this Dummy question. But, I just wanna get this straight in my mind.

In the Class Racer Info guide, I see that for many engines there are a couple of numbers listed for legal factory carbs, and either a 1901 or 1903 Edelbrock Q-jet, depending on whether the engine came with what we call a 750 or an 800 Q-jet. It appears that they are separated by their max allowable venturi size. So, for this post I'll just refer to 'em as a "big" or "small" carb.

So here are my questions:

(1) Have these rules been changed, or relaxed, to allow ANY small carb, for any GM engine that came with a small carb, and ANY big carb for any engine that came with a big carb ? Again, I realize that no carb can have a larger venturi size than what is listed as legal, for the engine.

(2) If the answer to #1 is no, then exactly which replacement Q-jets are legal ?

For example: Can you use a different number carb, from your engine brand, but not from another GM brand ?(such as a side inlet Chevy carb instead of a BOP front inlet carb)

And for the big carb engines, can you use any big E-carb, or just the 1903 ?

http://www.carburetion.com/Rochester.asp

02-26-2017, 06:30 PM	#1
oldskool VIP Member Join Date: Dec 2014 Location: The Land of Bayous, Boudin & Crawfish Posts: 1,668 Likes: 223 Liked 747 Times in 362 Posts	Current GM Q-jet Rules Please excuse this Dummy question. But, I just wanna get this straight in my mind. In the Class Racer Info guide, I see that for many engines there are a couple of numbers listed for legal factory carbs, and either a 1901 or 1903 Edelbrock Q-jet, depending on whether the engine came with what we call a 750 or an 800 Q-jet. It appears that they are separated by their max allowable venturi size. So, for this post I'll just refer to 'em as a "big" or "small" carb. So here are my questions: (1) Have these rules been changed, or relaxed, to allow ANY small carb, for any GM engine that came with a small carb, and ANY big carb for any engine that came with a big carb ? Again, I realize that no carb can have a larger venturi size than what is listed as legal, for the engine. (2) If the answer to #1 is no, then exactly which replacement Q-jets are legal ? For example: Can you use a different number carb, from your engine brand, but not from another GM brand ?(such as a side inlet Chevy carb instead of a BOP front inlet carb) And for the big carb engines, can you use any big E-carb, or just the 1903 ? http://www.carburetion.com/Rochester.asp