Jon Osborne cannot rebuild my 75 Q-Jet due to the baro sensor which is unique to 1975. The car is a completely stock 75 Riviera GS 455--do you guys recommend anyone else?ray:
Might try this site which I found on the net today. http://www.thequadshop.net/ I don't have any experience with this vendor although I know he advertises in the GSXTRA. (GSCA Newsletter) I'm also on a quest to understand / rebuild / modify my quadrajet, and just picked up Cliff Ruggles Quadrajet Book also. :3gears:
Cliff Ruggles is 9 months backlogged. :shock: If it's completely stock, why not rebuild it yourself? Rebuild kits are $20-25. Even if you need new throttle shafts, you can get a kit for about $40. btw, what's a "baro sensor"?
A very few Q-Jets (M4MCA and M4MEA) have a barometric (aneroid) device in them to compensate for different barometric pressures--altitude (primarily) and weather. It's not a sensor, it's a bellows connected to a metering rod in a fuel passage. I haven't seen one in twenty years or more. Most of the Mod Quads use a plastic "shot glass" to fill the cavity. Delco says "Adjustment should NEVER be attempted unless a replacement is required" And the NEVER is quoted exactly as they printed it--in caps. They also say not to dip the aneroid in carb cleaner.
OK...just looked in the Cliff Ruggles Q-Jet book, there's a little info on them in there. Looks like the bellows controls another power piston with a single rod / jet for even finer control of part-throttle mixtures. Cliff mentions removing it entirely, but you'll have to completely block off the passages to and from that second power piston and jet. It *looks* like you could rebuild it like a regular carb with little problem, assuming that the bellows/aneroid isn't shot. Any idea if they're still available as replacement parts? Bandit524, what shape is your Q-jet in? Worn throttle shafts? Do you know if the baro bellows thingy is working or not?
The Q-jet has never been off the car (to my knowledge). I'm the second owner--purchased in 1990 with 85000 miles. Runs fairly good: 12.5 mpg but its 32 years old (working unrelated pinginng issue) and thought it was time. If John had the correct parts, he required the car on his premises (75-76 only). That's quite a hike for a carb rebuild. Originally planned on doing it myself but the baro issue has me concerned. John says they are extremely sensitive and difficult to work with.
