Changing to a 4 Barrel Carb for a 1968
Short answer: Swapping a 1968 350 from 2-bbl to a Quadrajet 4-bbl isn’t difficult, but watch a few things: the intake casting, the throttle cable/bracket, and the air cleaner.
- Intake: spreadbore (Q-jet) castings are basically the same 1968–72. Avoid 1973+ (EGR) and 1976+ (restrictive ports, identified by a waffle imprint behind the carb flange). Some pre-1968 4-bbl intakes were squarebore (Carter AFB), and the 1967 Q-jet intake has an odd heat passage on the carb flange.
- Throttle cable/bracket: the 2-bbl cable won’t give full throttle travel. Reproduction 4-bbl cables are available from Performance Years; you’ll need to find or modify the bracket. (Pontiac used a rod in 1967, a cable for 1968+, and the design changed again around 1970–71 toward the Chevy style — so match the year.)
- Air cleaner: you’ll need a 4-bbl air cleaner (FGF, eBay, or Classical Pontiac classifieds for a stock-look one).
Any proposed updates, changes, pictures, and/or corrections, please use our comment section below (may need to click on permalink to access comments feature). Information is subject to change and offered as is without any warranties or guarantees. Please review our Term's Of Use for more information.
Content last modified: June 13, 2026 at 10:06 am
← Frequently Asked Questions
