Some carb advice for a new guy. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**MikeB** · 01-26-2026, 02:08 PM

I want to add that all Edelbrock Performer-series carbs use Air Valve Secondaries, not just the ones ones branded AVS and AVS2, which are adjustable. I copied this explanation from a Jeff Smith article:

"The AVS name is an acronym that stands for Air Valve Secondary. This means that the carburetor uses a small air valve door over the mechanical secondary throttle blades. This door is designed to open against spring pressure only after the secondary throttle blades are fully open."

What he didn't say is the air valve on the earlier Edelbrock carbs used a fixed weight instead of an adjustable spring. So instead of overcoming spring pressure, the air valve opened when air flow overcame the counterweight. Sometimes guys would lighten the weights, but that could introduce a bog.

Also, the AVS2 has a major improvement, and that's the annular boosters. Plenty of info about them in the Interment.

01-26-2026, 02:08 PM	#31
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 4,035	Re: Some carb advice for a new guy. I want to add that all Edelbrock Performer-series carbs use Air Valve Secondaries, not just the ones ones branded AVS and AVS2, which are adjustable. I copied this explanation from a Jeff Smith article: "The AVS name is an acronym that stands for Air Valve Secondary. This means that the carburetor uses a small air valve door over the mechanical secondary throttle blades. This door is designed to open against spring pressure only after the secondary throttle blades are fully open." What he didn't say is the air valve on the earlier Edelbrock carbs used a fixed weight instead of an adjustable spring. So instead of overcoming spring pressure, the air valve opened when air flow overcame the counterweight. Sometimes guys would lighten the weights, but that could introduce a bog. Also, the AVS2 has a major improvement, and that's the annular boosters. Plenty of info about them in the Interment. __________________ Mike 1969 Custom/10 LWB -- owned for 37 years. 350/TH350, 3.08 posi, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. Hedman stainless headers. Old Air installation in progress. 1982 Custom Deluxe 10 SWB -- converted from 250-six to roller cam 350 w/ Vortec heads -- sold 1981 C10 Silverado LWB, 305, TH350C -- sold, but wish I still had it! 1969 C10 (not the current one) which I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 26 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! Last edited by MikeB; 01-27-2026 at 01:30 PM.



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