Autoline Remanufactured Quadrajet Issues

SPOILER ALERT:
This thread addressed an idle problem with a newly remanufactured 4MV carburetor from Autoline on a 1971 Buick Riviera GS. It had no apparent idle fuel, ran off primary jets only and wouldn't idle less than 1000 RPM. Closing choke plate partially would raise RPM by 500. I believe the cause was a very thick and "squishy" gasket between the base plate and main casting. It deformed easily and tended to disintegrate when rubbed. I surmise that either the whole gasket or small fragments were responsible for blocked passages related to the idle circuit. Disassembly, minor cleaning and new gaskets resulted in a smooth idle between 500 and 600 RPM.
Happy reading - Chad Klink

Hello everyone. I've lurked on this forum for some time absorbing knowledge and this is my first time posting. I really appreciate everyone sharing their knowledge and experience here and hopefully helping me with my current issue (or one of them). Cliff, your book is fantastic. I've thrown in rebuild kits before but really never understood what was going on in the Quadrajet. I apologize for the novel, but want to give as much info as possible. I want to ask you guys if you think this is definitely a carb issue or something else I might be missing.

History: I picked up this 71 Riviera GS in 2005, ran it for a few days and then dismantled it to restore it. I was making good headway and then fatherhood and marriage came along in 2006. The project slowed and then stopped, but resumed again in 2016 or so. The sheet of paper I found under the seat claims Stan Fox from Milwaukee rebuilt the engine in 99 with forged crank, stage 1 heads, balanced, blueprinted and so forth. I didn't pull the heads, but when I was changing all the other gaskets, I saw Fox written somewhere in paint marker, can't remember if was under the intake or on the crank, so it might be a decent, mostly stock engine with about 4K miles on it.

Anyway, I screwed up terribly. Wanting to get the body work and paint completed, I traded money for time and bought a remanufactured carburetor from Autoline rather than rebuilding the original (7041544) myself. I now know this was a terrible idea. The new carb had a problem idling and seemed lean since closing the choke plate a little bit would result in an increase of a few hundred RPM. Backing the idle mixture screws out all the way provided some results, but not enough. I sprayed carb cleaner everywhere to try to find a vacuum leak, plugged all the ports, but nothing. Assuming that Autoline rebuilt the carb correctly, I decided to open the idle discharge ports to 0.090" to get a little more fuel in during idle. But when I got the carb on the bench, I heard on odd noise and found one of the secondary fuel discharge nozzles rolling around on the throttle plate below! I initiated a warranty return through Rock Auto and had a replacement carb (7041540) the next day.

I put the new carb on, filled the float bowl and, bam, she fired up and was on high idle running beautifully. The engine warmed up, I kicked it off high idle and it was PERFECT. No cloud of hydrocarbons filling the garage and you could have built pyramid of champagne glasses on the air cleaner. It was simply amazing to see this motor run so slowly and smoothly. I actually turned the idle up to 700 RPM. I shut it down and finished hanging the new dual exhaust system I was installing (stock manifolds, 2.25" pipes, Walker Quietflow SS mufflers). Two days later, I choked it, started it and it seemed a bit lean. I adjusted the linkage to close the plate just a bit more and it helped. After it warmed up , I kicked it off high idle and it died. Now, it seems like there is NO idle fuel at all and it will only run with the primaries open enough to get fuel spraying from the primary nozzles. The idle mixture screws have no effect at all. I read more here and decided to make sure mechanical advance wasn't the issue (power timing your Buick V8 is an awesome thread). I wasn't happy with how erratic it was at idle and wasn't even sure what the later HEI distributor was out of . So I put in a remanufactured Cardone 30-1894 for a 75 Buick 455 last night. Now I have stable timing at idle (900-1000 RPM is as low as I can keep it running) and a predicable mechanical advance. It's got fresh 91 octane, no ethanol fuel pulled right from a gas can below. The filter is clean. Fuel pump is new. New cap, rotor, plugs, etc. I've got 20-25 in of manifold vacuum at 1500 RPM with the choke plate slightly closed. I've blocked off all the ports just to make sure I didn't have leaks from the vacuum modulator, brake booster, charcoal canister, vacuum advance, climate control, etc. I just don't get it. I can get it to idle at about 950 RPM and it will rev to 1500 when you close the choke plate a little. It ran perfectly for 20 minutes the first night but runs like crap now. It smooths out at 1500 RPM. Pops once in a while when opening it up fast.

I contacted Rock Auto to see if they're willing to send me another carb and they're done with me, lol. They're offering a refund plus the $75 I got for my core (which is gone forever). I want to ask you guys if you think this is definitely a carb issue or something else I might be missing.

Thanks for taking the time to read this and for anything advice you can offer,

Chad

 

Grab a compressed-air blow-gun with a rubber tip.

Remove idle mixture screws. Blow compressed air into the idle mixture screw holes. You better see a bit of gasoline blow out of the idle air bleeds inside the choke housing.

Reinstall idle mixture screws. Run engine. See what happens. Engine may not run 'right" for several seconds due to mild flooding. Should clear up quickly.

No compressed air? Try aerosol carb spray via the little plastic straw. Less volume, less pressure--but probably still enough to dislodge minor contamination.

 

Brad, that sounds like good advice. I've read many favorable posts on Mark's work and will probably consider buying one from him should I determine this to be a hopeless carb. Thank you for the recommendation.

Schurkey, I've got a good Quincy 5hp 60 gallon so I can sandblast and paint. I finished up with blasting and shooting epoxy primer on the undersides of the trunk and hood today and tried your idea after cleaning up. Yup, fuel shot out of both idle bleeds. However, the problem still persists. Thank you for the suggestion though.

After blowing out the idle circuit with air, I got to thinking about fuel level within the carb. What's been nagging me is not having a fuel pressure tester and being able to say for sure that my pressure is good. I'm going to order one to add to my arsenal. When disconnecting the line from the carb, plenty of fuel gets shot into a bottle while cranking, but I don't think that's a good test. I filled a clean wash bottle with fuel and artificially raised the fuel level by injecting a slow, but steady stream of fuel into the vent tube. Immediately, RPM went from a stumbling 1000 to a smooth 1500 or so. A few seconds after stopping with the wash bottle, the RPM returned to 1000 and very rough. I got a screwdriver out, used the wash bottle again to inject fuel down the vent tube and was able to back the idle adjustment screw out and got the RPM down to normal and it was smooth as silk. I stopped adding fuel and the engine died about 5 seconds later. I'm wondering if fuel pressure or float adjustment is the problem here. What do you think?

 

Fuel pressure, float adjustment, or plugged needle/seat. Possible plugged fuel filter, if there's a filter in the inlet of the carb like stock.

Given that you have plenty of volume when you disconnect the plumbing and crank the engine...I'd yank the inlet nut to inspect the filter, and then pop the top off the carb to check float level and the needle valve.

 

You'll probably have to yank the idle tubes out and replace them with new ones drilled to .038". YouTube and Cliff's book will help you if you're a do-it yourselfer. The Idle down restriction will also have to be enlarged to .053"-.055". The idle mixture discharge port (mixture screw) .085"-.090" is ok, you may have to cut the spring on the screw if binds before the screw seats. Call Cliff for kit and Jet/Rod combination. Or as previous post said, send the carb off to Ken @ Everyday. Before anything, make sure all the screws are tight on your new carb. Best of luck.

 

Shiftbyear, thanks for the advice. You know, I checked the screws above and below and were surprised how loose they were. I didn't want to warp anything so I snugged them just a bit, maybe a couple of foot lbs. Just guessing since my torque wrench is good to about 10 ft lbs. Yeah, I'm totally comfortable diving into this and enjoy the work. This project has been all about learning for me and an excuse to buy tools and work with my hands. Getting a Boattail out of it in the end is a bonus. It's not a numbers matching car and should have been parted out to begin with. It's a Frankenstein monster I built out of two 71's, a trunk pan from a 73 and a good part of a 4x8 sheet of 18 gauge steel. It was a stupid project I started before realizing I could have driven a solid car back from Nevada for $5K to start with. Oh well, I'm supporting plenty of US businesses and several cottage industries with this. I went through Mark's website and he's got everything I need. I might even drill it and put in bushings while I'm at it.

Schurkey, the filter is new and in the fuel inlet. It's new and clean. I think I'll take your advice and pull the top of the carb off to take a look to see if it's something simple. Now that the weather is warm enough for me to paint in my garage again, I need to focus on getting it painted and reassembled. I get distracted too easily and off task with rebuilding stuff that makes sense to while it's apart. I should leave that stuff for the winter months. I gotta get this car back together. My son's 13 and wants to start on his car, whatever that turns out to be. Something 60's and GM, though he really wants a 67 Impala, like the car from Supernatural. Sure thing Jack. That's a little pricey!

Again, I really appreciate everyone's advice. This forum is fantastic.

 

Is the tank and Lines new? I'd pull that carb filter and check it out. No telling what might have gotten up out of the tank or lines. If nothing, you know for sure.

 

Chad, going from experience and that of others on the board. Go with Ken at everydayperformance.com, his carbs have the best reputation around and for damn good reason.

 

X2 I bought one from Ken it looks amazing and works great. He will build it to suit your car combo you have.

 

Toss that Autoline & Cardone carb in the dumpster.

Reman'd Q-Jets are built to do one thing: pass emissions testing. That's it. This condition includes not being able to idle your engine at all, hence zero emissions. Their cores get screwed up so badly that even professional rebuilders can't fix them. Humpty-Dumpty.

If you still have your original core: splendid. Send it to Ken, and you'll be golden.

 

Ken @ Everyday Performance x 10000

 

Guys, thanks for the advice regarding Ken. I've read tons of good things about Ken here. Unfortunately, I don't have my core. Ken's got the carb for my car, but I'm not quite ready to put $1500 into a car I don't have road worthy yet. Not sure if this is related, but the base gasket looks thick as heck and is spilling over into the venturis. If I rub my finger on it, it erodes away. Fuel pressure was 5PSI.

 

You don't exactly need to put your stock carb on, meaning a numbers matching one. I bet he can craft you an 800 cfm quadrajet in the area of $400-500 depending on what you want done to it.

 

I bought a FULLY restored 72 Qjet from him and it didn't cost me no $1500 and I'm in Canada with the exchange rate applied and duty charges. Are you trying to get a gold plated one year only stage 1 carb from the bottom of the Titanic or something?? Lol

 

Well, almost... 71 but not from the Titanic, lol. Basically, I was looking to see what Ken had ready to go for a 71 and later Buick:
http://www.everyday-performance.com.../inview=product72757350&offset=0&sort=nameAsc

From what I read, I have a lot of options. It's a Frankenstein car, so I don't really care about numbers. I'm not even married to the divorced choke and can run ignition to an electric choke pull off. By the times I finish putting new brakes in my DD, my gasket kit should be in and I'm going to dig deeper into this thing and learn.

 

Problem solved. I'm almost certain it was Autoline's choice of throttle body gasket. It's very soft and foam-like. It deforms so easily it had spilled out into the venturis by at least a 32nd of an inch. It also crumbled to the touch when I was inspecting it. I suspect it was interfering with the idle circuit by blocking passage between the base and main casting. I couldn't tell for sure because the gasket simply fell apart when I separated the base from the main casting. For being a remanufactured carb, the detail to cleaning was disappointing. I gave it a thorough cleaning, ran enough cleaner and copper wire through everything, verified the float level and put it back together with a new set of gaskets. After setting the idle mixture, I can back the idle adjustment all the way out and she idles at 525, and still idles smoothly in gear. Lesson learned on remanufactured carbs. Especially those from Autoline.

Thanks to all who jumped in and offered their advice. Now, back to block sanding.

 

I'm glad you got the carb issues solved Chad!