Hi All, I have a very nice 68 California GS350 with a 4bbl Quadrajet #7028244. The engine idled nicely, ran smooth at low and high speeds and is a delight to drive. The carburetor did, however, leak at the gaskets, around the accelerator pump shaft on top of the carburetor and at the idle compensator. I really didn't want to touch it, but a leaky carburator is not cool. I looked into a professional rebuild/restoration (395 bucks) from one shop, or a rebuild for 160 bucks from another large commercial operation but too many horror stories there. Decided to rebuild it myself hoping that all It needed were gaskets. I changed out the accelerator pump, check valve, gaskets, vacuum pulldown and dashpot. (the plastic in both the original pull down and dashpot was so brittle they broke in my hand). I gave the carburetor a very good cleaning, blew everything out with compressed air and reassembled it turning the screws out 1 1/2 turns which was where they were before I took it apart. Once fuel got into the bowl, the engine fired instantly and it settled down to a nice, smooth fast idle. The bad news is after it warmed up and came off the choke, it idled terribly, lumpy, surging and wouldn't keep running. I enriched the screws another half turn but had to turn in the idle throttle stop screw to keep it running. The problem seems to be isolated to the idle/low speed circuit. If I depress the throttle just a little, the engine is not smooth and she surges intermittantly.. I tried to keep everything the same to the extent I could hoping to stop the fuel leaks and have a nice running engine but something went awry here. Any ideas. The car was stored many years (approx 15-17). When I got it, it started right up and ran fine except for the fuel leaks. I re-set the timing to 2 degrees BTDC, and adjusted the mixture screws with a tach and vacuum guage and I ended up at 1 1/2 turns out on each screw. The carburetor was suffering from fuel seepage out of the plug caps at the bottom of the bowl. I did epoxy them when I had it apart. It starts fine - just won't idle smoothly. The engine has 71xxx miles on it. Externally, the only item I'm not sure of is the idle compensator on the front of the carburetor adjacent to the accelerator pump. I don't recall if its normall closed and raised by the small link between it and the accelerator pump lever. Right now at idle, its open - that is the rubber seal on the bottom of the bi-metallic spring is not flush on the hole. Wondering if perhaps I bent it while cleaning it. Something else to try while she's idling - press down on the compensator to close off the hole. Probably more than you needed to hear, but I'd welcome any ideas anyone has to offer. Thanks Tonino
The first thing I would do is get some ether and make sure you don't have a vacuum leak somewhere. Second thing I would do is give it more timing, not that I think it is your problem, but just because.
Thank you for the reply Lonnie, I've been all over the carb. looking for a vacuum leak and haven't found anything but admittedly I didn't use "ether"? All the fuel leaks have ceased, even around the accelerator pump shaft and idle compensator. When I get time and get a buddy in the garage, I'll have him push down on the compensator while the engine is idling and see if that changes anything. Don't want to muck with the timing until I get it up and running the way it should with its baseline specs. Tonino
It sounds like what you are calling the idle compensator is actually a vent, which opens at idle to release fumes when the throttles are closed. You seem to have a lean condition at idle, i would replace the idle tubes since they provide the fuel at idle. While you have the carb apart i would get a straight edge and check all the gasket surfaces, a warped casting will allow internal vacuum leaks and a lean idle. Also make sure no fuel is dripping from the fuel nozzles during idle. Today's fuel requires a 5 to 7 percent increase due to the ethenol, so you might need to richen the entire fuel curve from stock. Cliff ruggles book has helped a lot of people on this site understand the qjet systems and is very helpful and his rebuild kits are excellent. Good luck
I would say Vacuum leak also, spray starting fluid everywhere and hopefully its the base gasket, or the rear throttle shaft bushings, the majority of leaks are these 2 places after a re-build.
Idle tubes plugged up or "varnished" up internally a bit. I see this a LOT with home rebuilds. They really need to be removed and cleaned/replaced, or at a minimum cleaned out during the rebuild. Another possibility in addition to a vacuum leak is wrong gasket between the main castings and baseplate. If equipped check for a vaccum leak at the Hot Idle Compensator, rear of the main casting under the metal cover. Hopefully you used good parts for the rebuild, and not a generic over the counter kit, or you'll be going back in it anyhow.....Cliff
Thank you for the reply Shiftbyear, and you are correct it is the vent. I just finished re-setting it to spec. and got myself educated on what it does and how it works (My first Q/jet). Haven't tried running it today, but the more I think about it, the more I'm leaning towards what everyone is saying re. vacuum leaks and warped castngs. Today while adjusting the vent and measuring the height of the acc. pump shaft when the vent just closes, I noticed fuel burbled near the top of the air horn (front right) when I pushed the throttle back. That didn't look right so I need to investigate that as well. Hadn't thought about the lower energy level in todays ethanol fuels, but what you're saying makes sense. All my cars perform better and with better economy on non-ethanol fuel. Will bear your advice in mind about enrichening when I get this beast running right. They say "assumption is the mother of all catastrophys" and to avoid that I went to my local AC/Delco dealer for a rebuild kit whereat I learned they don't make them anymore but happily took 18 bucks for an aftermarket kit. Needless to say, I was not impressed with the quality of the kit. The gasketing was clearly inferior to what I took off and the needle seat did not have the windows cut in the bottom so I didn't use the kit needle or seat. So much for my AC/Delco store. The moral of the story is that I took apart a perfectly functioning carburetor only because it was leaking fuel around the gaskets and accelerator pump shaft and ended up with a crummy idle. in spite of my best efforts, I could also very well have gotten some foreign matter in places where it doesn't belong during my cleaning/scrubbing frenzy. I'll try it again tomorrow, but I sense another disassembly of the carb. is looming on the horizon. Tonino
Hi Cliff and thank you as well for the reply. If you're the one and only Cliff Ruggles - the author, I'll be looking for a copy to buy. My carb has the hot idle compensator. I took that apart and cleaned it all up, blew it out and re-assembled it. Will check back there again. As I told Shiftbyear, the rebuild kit was not very good quality. I did observe the tightening sequences and let the carb sit 24 hours then re-torqued everything before I installed it. The gasket between the midsection and throttle body may have been a little thinner than the one I took off The gaskets in the kit were a thick composition type but the top gasket under the cover was thin paper -like. All the gasketing I took off the carburetor was composition and appeared to be much better quality. The needle seat did not have the windows cut in the lower part of it like my original, so I didn't use it or the needle. Since the only problem I had prior to disassembly was fuel leakage past the gaskets (the carburetor actually functioned perfectly well i.e., smooth idle, excellent throttle response and good power throughout the operating range, I probably didn't pay as close attention to idle tubes as I should have. Nor did I check the mating surfaces with a straigh edge. I did use copious amounts of cleaner on everything and blew everything out with compressed air. Each carb section had its own little tray and I cleaned each one separately but perhaps not good enough. Now all I have is a crummy idle and low speed surge but it responds very well to the throttle with no hesitation. I'm going to name her "leaping Lena" - LOL. Yeah, you guys have me just about talked into pulling it again. I should have had that beast idleing in short order so its not a question of not getting the mixture settings right. Something is awry internally. Will keep ya'all posted. Tonino
Hi Stage one, See my "trials and tribulation" responses to CliffR and shiftbyear. I do have some starting fluid here somewhere and I will give it a try when I give her another go tomorrow. Come to think of it, I never connected "Lonnies" ether and starting fluid together - DUH!! Might as well try it everywhere else too. Tonino
Not using good parts leads to not getting a good end result. We supply a plus .015" thick gasket in all our kits for the early carburetors as the thin one seldom effectively seals things up. The accl pump in your over the counter kit is doomed, none of them, even with the "blue" seals on them will hold up in this new fuel. Absolutely NOTHING wrong with ethanol in the fuel and no need to avoid it. Just use good parts and worry about something else. The HIC is NOT needed, neither is the vent in the bowl so adjusting it is meaningless to carb function. I would block the hole under the HIC, to eliminate that area as a possible vacuum leak.......Cliff
For: Cliff R., Stage-1, shiftbyear and Lonnie. I would classify this as "another one of lifes unexplained mysteries", or just plain old "Dont Ask" Dept. The only thing I did last night was to install a new dashpot and set it in accordance with the old one. Started the beast and she fired right away on fast idle. Sprayed carb cleaner all over the seams and could not detect any suction anywhere. Let it run on the high step of the cam until the upper radiator hose warmed up, blipped the throttle and the choke released about halfway and the idle speed reduced and sounded good. Let her run longer until the upper radiator hose was at normal temp and blipped the throttle again. Choke released completely, idle speed dropped off to about 600rpm (in park) with no surging, no rocking and rolling - "no nuthin". She seemed happy. I then hooked up the vacuum gauge and tach. Was reading about 17.5 on the vac. guage with a steady needle. Tweaked (leaned) the mixture screws in and raised the vac. to 19.5 with a steady needle. Took her for a spin and she ran perfectly well. I therefore declared victory, pulled her into the garage and promptly popped open a cold one. The only thing I can think of is perhaps yesterday I pulled it off the high idle too soon and she was still cold. But she sure didn't act that way. Whatever - she's fine now. Thanks for all the advice. I will save all your comments in a folder for future reference - its all very good advice. and thanks again. Cliff - I would like some contact info on your business, the name, do you have a website I can visit. Regards to all Tonino
Ordered the book from you earlier today, Cliff. I don't claim to know it all, and I have some little issues that I believe are carb related.
Hi Cliff, Ordered your Q/Jet book today. Am going to look for a #7028244 Quadrajet to use as a project carb, strip it completely and rebuild it for enhanced performance on my California GS. Looking forward to it. You'll probably be hearing from me as I order parts and ask questions. Don't need to break drag strip records - just want her to run with a little more oomph. Thanks again. Tonino
