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I have a 1974 Cutlass Supreme 350 cid with the original Quadra jet(?) carb. When I bought it a couple years ago it started fine but wouldn’t Idle right and would die sometimes at lights. I watched an explanatory video and followed the instructions and thought I had it dialed in pretty good. Started running and idling perfectly with no more stalls. However it has become progressively harder to get started. Starts in a split second with started fluid into the carb and runs perfectly after that. But just about can’t get it started any other way these days. Any suggestions?
2nd question maybe for a different thread. The shop that does all my work, last spring they did a whole bunch of stuff on this car, brake lines, new steering parts, fixed and exhaust leak, etc… said that the carb needs to be replaced. I asked about having it rebuilt and they didn’t seem interested.
This shop does good work but they are really busy (they do most of the classic mechanic stuff for one of the big custom shops in town which is next door) and they’re not cheap so I know they’d rather just replace and get it running right then mess around with a rebuild. But this is a nice classic and Id like to keep it pretty original, but I also need it running right so I wanted to ask the opinions in here are.
I’ve been warned by another cutlass owner in town, absolutely do not by a remanufactured quadrajet either have the original rebuilt or get a nice aftermarket.
Whether I buy a nice new edelbrock or whatever I’ll keep the original so it stays with the car going forward.
What should I do? If a new one any suggestions on brand and model? I’m a woodworker who loves classics, I’m handy but I’m no expert on this subject. Need guidance.
If it's the original carb, after 50 years it's probably time for a clean and rebuild. Your carb number should be 7043250 if a 350 or 7043251 on a 455. You can find it at the left rear side of the carb body.
How handy are you mechanically? In other words, armed with the 1974 factory shop manual and a bucket of carb cleaner, do you think you could remove, disassemble, clean and reassemble it? If not there ARE trustworthy and competent people who can do it for you and set it up properly. You'd have to ship it to them though.
That's an awfully nice looking Cutlass. Don't let just anyone mess with it. Though I can't understand a shop dealing with older cars that's unwilling to tackle a QuadraJet rebuild. It's a half day job tops depending how grungy the carb is and how long it needs to soak.
Don't let them talk you into a Holley or Edelbrock either. That's a cop-out solution and the engine won't perform as well as what the factory engineers designed for it.
Last edited by rocketraider; Yesterday at 02:39 PM.
Send it to a carb specialist and have it rebuilt. Due to its age it will probably need to have the throttle shaft bushings redone, this is more than cleaning and new gaskets. Stick with the original Qjet, you'll be much happier.
Agree with keeping the Quadrajet. I have found most people afraid to work on them that's why they recommend an aftermarket replacement carb. One other thought and suggestion is the fuel that you're using. Not sure about and other members but I have found with mine it idles and drives perfectly fine but always is a hard start due to the amount of Ethanol in the fuel. The fuel "boils" out of the carb bowl and therefore is dry to start. If I run Ethanol free it starts, idles and drives beautiful!
I read some articles (lost art of choke adjustment in Hemmings) and threads and watched some videos and from what I can tell the choke plate is not closing all the way. There seem to be at least two things contributing to this that I can see.
1. The choke spring is not tight or at least not tensioning the lever to snap the plate closed and so the plate is limp and doesn’t spring at all. Just hangs open. The only way I can get the spring to tension and close the choke plate is by turning the dial so far to rich the indicator line is far beyond the notches. It will start and idle high but doesn’t sound or smell right and keeps trying to turn over after I shut it off. I guess that’s Running rich?
-I have taken the choke spring cover off probably 20 times but I can’t seem to find a way to tension the spring against the lever without turning the dial beyond rich. The spring seems to be fixed to the dial positions. Is there another adjustment I’m missing?
2. The pull off break(?)(I really hope I’m using the right term here haha) may not be operating properly. There seem to be 3 positions, 1 all the way back where the choke plate can fully close, one slightly forward which opens the plate just a crack, and one all the way forward that opens it all the way. I could be wrong but I think the pull off break is returning to the 2nd position when the car stops which keeps the choke plate open a smidge.
You can see the indicator line in the middle of the markers and the choke hanging open. In order to get it to tension the choke plate I have to run the dial counter clockwise to beyond the 12oclock position. Is the position of that indicator line unimportant? Is all the matters the spring tension in the end or does the position of that indicator line and the dial determine some part of the mixture independent of the spring and choke plate?
I realize I only know enough about this to get myself more confused so stop me if I’m a hot mess.
After getting it running and idling right I feel like I’m so close to having it dependable if I can just fix this starting issue without any major downtime haha.
Last edited by Cinnamon Gravy; Yesterday at 09:26 PM.
I read some articles (lost art of choke adjustment in Hemmings) and threads and watched some videos and from what I can tell the choke plate is not closing all the way. There seem to be at least two things contributing to this that I can see.
1. The choke spring is not tight or at least not tensioning the lever to snap the plate closed and so the plate is limp and doesn’t spring at all. Just hangs open. The only way I can get the spring to tension and close the choke plate is by turning the dial so far to rich the indicator line is far beyond the notches. It will start and idle high but doesn’t sound or smell right and keeps trying to turn over after I shut it off. I guess that’s Running rich?
-I have taken the choke spring cover off probably 20 times but I can’t seem to find a way to tension the spring against the lever without turning the dial beyond rich. The spring seems to be fixed to the dial positions. Is there another adjustment I’m missing?
2. The pull off break(?)(I really hope I’m using the right term here haha) may not be operating properly. There seem to be 3 positions, 1 all the way back where the choke plate can fully close, one slightly forward which opens the plate just a crack, and one all the way forward that opens it all the way. I could be wrong but I think the pull off break is returning to the 2nd position when the car stops which keeps the choke plate open a smidge.
You can see the indicator line in the middle of the markers and the choke hanging open. In order to get it to tension the choke plate I have to run the dial counter clockwise to beyond the 12oclock position. Is the position of that indicator line unimportant? Is all the matters the spring tension in the end or does the position of that indicator line and the dial determine some part of the mixture independent of the spring and choke plate?
I realize I only know enough about this to get myself more confused so stop me if I’m a hot mess.
After getting it running and idling right I feel like I’m so close to having it dependable if I can just fix this starting issue without any major downtime haha.
Re-read Post #2 and #3. Make sure they put in a new spring for the choke too.
If it's the original carb, after 50 years it's probably time for a clean and rebuild. Your carb number should be 7043250 if a 350 or 7043251 on a 455. You can find it at the left rear side of the carb body.
How handy are you mechanically? In other words, armed with the 1974 factory shop manual and a bucket of carb cleaner, do you think you could remove, disassemble, clean and reassemble it? If not there ARE trustworthy and competent people who can do it for you and set it up properly. You'd have to ship it to them though.
That's an awfully nice looking Cutlass. Don't let just anyone mess with it. Though I can't understand a shop dealing with older cars that's unwilling to tackle a QuadraJet rebuild. It's a half day job tops depending how grungy the carb is and how long it needs to soak.
Don't let them talk you into a Holley or Edelbrock either. That's a cop-out solution and the engine won't perform as well as what the factory engineers designed for it.
I could probably figure it out, I’m pretty handy when I have guidance but might be easier to just send it in some where. I’ve found a bunch of carb rebuild videos and I’ll probably watch a few just to get the jist and then start calling around to find a shop that does it.
thought I had it dialed in pretty good. Started running and idling perfectly with no more stalls. However it has become progressively harder to get started. Starts in a split second with started fluid into the carb and runs perfectly after that. But just about can’t get it started any other way these days. Any suggestions?
Need more information. Are you pumping the pedal 3-4 or more times before starting? Have you verified there is a stream of fuel when the throttle is actuated? Could be the accelerator pump is not working, which is a simple fix. Or could be a cracked rubber fuel line that causes fuel leak down.
I could probably figure it out, I’m pretty handy when I have guidance but might be easier to just send it in some where. I’ve found a bunch of carb rebuild videos and I’ll probably watch a few just to get the jist and then start calling around to find a shop that does it.
You may be pretty handy. You might be able to rebuild the Quadrajet yourself. If you look for a carb rebuilder, you WANT someone who is very familiar with Qusdrajets, not a shop that claims they do all carbs. Doug Roe and Bill Travato have books to tell you all about your carb.
Since your profile doesn't show what state you live in, we have no idea if a good rebuilder could be near you.
Yesterday, 01:17 PM
