So I've got another (probably stupid) question... But I can't seem to find an answer anywhere, and I'm not experienced enough to figure this out for myself so... Anyhow. I just put a rebuilt Quadrajet on the Riviera. It's not identical to the one that's on it, but it's close... it's off of a '74 Buick instead of a '73 according to the casting #. Hooked everything back up, figured i'd start it without adjusting anything just to see if the rebuilders got it close. No go. Car ran for about 5 seconds and then only if I kept my foot on the accelerator, then quit. So I tried to count the number of turns the mixture screws on the old carb were set for... I think I got it fairly close, but I'm not sure... tried to start it again, same thing. Car runs for a few seconds and then stalls. I know the timing is basically correct (or it should be)... What I'm wondering is if anyone can give me some kind of a ballpark idea of how many turns I should start with on the mixture and idle screws. Also, what's the screw that the throttle linkage rests on for? Obviously, it's got something to do with idle speed (I'd think), but I thought the idle screw was on the passenger side of the carb. Any help would be appreciated... I have no real hands on experience working on cars (just what I've read about how everything in them works) and part of the reason for buying the Buick was to learn... but I'm totally in the dark on most of this stuff. =/
Idle speed screw is on the drivers side. The screw on the passenger side is for the fast idle cam when the choke is on. Is your choke working? The symptom you are reporting sounds a lot like a choke that is not operating. I usually start with 1 1/2 to 2 turns out on the screws, then adjust for max vacuum.
Choke was working with the old carb as far as I know... looks like it's working on this one; the flap is staying closed. I may have the mixture screws backed out too much. I'll try seating the two screws on the front of the carb and backing them off about 2 full turns, see what happens. Thanks Also... I had the 'privelige' (such as it was) of driving a customer's '62 190SL Mercedes in and out of the shop the other week a few times. Would be a very nice little car if it didn't need so much help. Anyhow... that thing has a manual choke. And it'd run cold with the choke all the way in (which is open on that car, I think) as long as you kept the revs up... wasn't happy about it, but it worked. As it is now, the Buick won't stay running period, regardless of whether my foot is on the gas or not. Not sure if that rules out the choke or not...
Does it stall because of too little fuel, or too much fuel? Where is the choke pulloff set? Does the pulloff work? Is this a production-line rebuilt carb? If so, the numbers on the side mean NOTHING; you may not even have a matched set of Buick castings; and there's no guarantee whatsoever that the jets, metering rods or hanger is correct. Production-line rebuilds (carbs or engines) are basically headaches in a box. You're way better off to take a decent core carb and rebuild it yourself--at least that way all the parts are designed to work together.
Was stalling because of too much fuel, apparently. The old carb was set for something like 4-6 turns out. Set it to 2 turns, it now runs. Very badly. Does not want to idle, idle speed is way too low- seems to be about 600-625 in park according to my tach. Choke is fully open and the manifold is pretty warm after only 30 seconds or a minute of operation. No idea what the choke is set at though. Tried to adjust the idle speed, had the spring compressed almost entirely and the rpms weren't changing that I could hear (couldn't read the tach from that side of the engine compartment with where I put it)... it also doesn't run very smoothly at all, even if i put my foot on the gas to hold the rpms up a bit. Gonna go re-read the shop manual for the eleven trillionth time.
Ok. Got it running passably well. It still runs far more roughly than it should, but it doesn't want to stall or anything, it idles about 700 in drive. dieseled just a bit when I shut it off, which I *think* indicates it's a little rich. Gonna drive it to work tomorrow or on Tuesday and get my boss or one of the techs to help me fine tune it (hopefully)... The mixture screws don't seem to have any effect at all on engine RPM. But it's only a few miles, I think it's running well enough to get there without damaging anything. We'll see, I guess. Did run into one issue... the new carb has one less vacuum port than the old one. Not sure what I'm going to do about that yet.
Is the carb from a 350? If it is it will never run right on a 455. There are internal passages that are different on 350 carb.
I have absolutely no idea what car/engine the carb is off of, I'm afraid. I can get the casting number off of it when I get home if that helps. I think the choke needs to be adjusted... I had to start it this morning and pull the car forward a few feet so it wasn't blocking the mailbox, and it wasn't interested in starting at all. It started fine yesterday when I was tuning it, but of course it was warm at the time, so... If all else fails I know someone who's got a Jet rebuilt q-jet that they're not using... I can try that.
Thought you guys might like to know the outcome. I had my boss look at it today. This is the first time I've ever tried to tune a carb, and I was totally puzzled, so I asked him for help. Unsurprisingly (at this point), the carb is bad. Had both mixture screws seated and it was still running-and running too rich at that. Also had very little vacuum to speak of (something like 5in, iirc), which was not a problem with the old carb. So yeah. Right now I'm trying to decide between having the q-jet rebuilt properly or putting something else on it.
You said it was dieseling, is your timing correct? Also, if you have points check your dwell angle. It sounds to me that if its dieseling, your timing is too far advanced. Are you running vacuum advance? And as far as your idle mixture screws not having any effect on the idle, it could be a number of things. The screws themselves may have been screwed in too far before and have a ring around them which would render them useless, whoever built your carb last may have assembled it wrong and bent a primary metering rod which would allow fuel to pour into the engine unmetered. Let us know... -Cort
Timing is correct as far as I can tell. We'll see what happens when I get the carb back from the rebuilder. These guys have a good reputation so we'll find out. If it doesn't run right after they've rebuilt it chances are I've opened up a whole new can of worms and have other problems now. Which wouldn't be good as there's no room in the driveway or the garage for it (or the Subaru, for that matter)... and it'll just be in the way at work. And I don't think the neighbors would be very happy with it being seriously worked on in the street. Frankly I'm surprised they haven't had a fit about it and the Mercedes being parked in front of the house and dripping oil all over the place for the past 6 months... Ah well. One problem at a time. No sense in even worrying about it until I get the carb back on Wednesday.
I assume. at this point, that this stalling problem is occurring cold. It is likely caused by the choke pull offeither nor working, or not properly set, causing the engine to flood when started cold. First, make sure that the pull off is set properly. With the engine overnight cold, try retracting the linkage on the pull off, with your hand. It should pull the choke blade open about a 1/4". If this is correct,create a vacuuum on the diaphragm, looking for the choke to open the same amount. If it does not operate the diaphragm, replace the diaphragm, and readjust. If it does operate correctly, check for vacuuum on the port, and check the hose for leaks. Just replace it, to humor me. We'll start there. Ray
