Dwight Romberger Posted July 31, 2013 Share Posted July 31, 2013 (edited) Hi all,My '30-40 has a "came from the factory with" Marvel T3S.The only mixture adjustment is the air valve knob.The engine rolls and sounds like is going to stall at all speeds.It was running smoother before I replaced the fuel lines (tank to pump and pump to carb)Starting with the knurled air valve knob flush with the pointer, if I turn the knob to the left/counterclockwise (leaner?) far enough it will hesitate and stop.If I turn the air valve to the right/clockwise (richer?), I can turn it all the way in with no change in engine speed or characteristics.Does this seem like a problem with the air valve?(New points, condensor, coil, wires. Pulled all plugs. They are clean. Spark at every plug. Gap and timing correct. Plug wires separated from each other)(Vacuum inlet for wipers plugged with brass plug. Intake bolts tight. I didn't have WD-40 to spray to look for vacuum leaks, but I used brake cleaner. I think that would serve the same purpose?)I would appreciate any suggestions.Thanks,Dwight Edited July 31, 2013 by Dwight Romberger (see edit history) Link to comment Share on other sites More sharing options...
Leif Holmberg Posted July 31, 2013 Share Posted July 31, 2013 Dwith.Thanks for the Griffen sites.Are you sure you have the right mixture adjustment air spring.Leif in Sweden. Link to comment Share on other sites More sharing options...
Dwight Romberger Posted July 31, 2013 Author Share Posted July 31, 2013 It looks like the one in the pictures- fat in the middle, skinny at both ends (sort of like me!)I don't know how old it is though. Dwight Link to comment Share on other sites More sharing options...
Mark Shaw Posted July 31, 2013 Share Posted July 31, 2013 Re: How to adjust Marvel carb? 1923 Buick running rich<!-- google_ad_section_end --> First, we must assume that the fuel & ignition systems are working and adjusted correctly. Generally, all Marvel carbs will run rich when adjusted to run correctly at idle when the engine is still warming up. Therefore, it is very important to get the engine up to temperature before making any adjustments. So, get out and run it around the neighborhood first. Start with the big knob even with the end of the tang that clicks in the grooves of the knob. Start with adjusting the fuel supply needle valve at the bottom of the carb 1 1/2 turns out to start.With the engine warmed up and the choke fully open, retard the spark and adjust the air screw (the big knob) to the left until the motor hesitates. indicating the mixture is too lean. Then turn it to the right a few notches at a time until the motor runs smoothly. Then, open and close the throttle to see if it hesitates or stalls on acceleration. If it does, then turn a few more notches to the right until the hesitation is eliminated. With this done, advance the spark and terrorize the neighborhood again, or take it out on the road and run it for at least an hour before checking the plugs to see if it is running leaner. You could also just mark the air screw to see how the new setting differs from where it was. You can try increasing the bottom needle valve to get more power, and re-adjust the air valve as before until you get the most from the engine.Good luck,Correct air spring inside the big knob: Link to comment Share on other sites More sharing options...
Dwight Romberger Posted July 31, 2013 Author Share Posted July 31, 2013 Thanks Mark. The spring looks like yours. I have adjusted the air valve the way you describe. It has no effect whatsoever on the rough running. Link to comment Share on other sites More sharing options...
Bob Engle Posted July 31, 2013 Share Posted July 31, 2013 Sandy will tell you to clean the jets. dirt and varnish can buildup in the jets and will cause the engine to run rough. Any time the gas evaporates out of the carb, you risk problems with varnish. Drive them frequently to prevent the problem.Bob Link to comment Share on other sites More sharing options...
Dwight Romberger Posted July 31, 2013 Author Share Posted July 31, 2013 OK. Will do.Thanks Bob. Link to comment Share on other sites More sharing options...
Guest outlaw car man Posted July 31, 2013 Share Posted July 31, 2013 I certainly will agree with Bob on that. My Marvel book shows, I think, 3 standpipes/jets in the 30-40. In my experience with the Marvels, the low speed jet is usually the problem, as Bob says gums up. I pretty much only deal in 33 Marvels, but my guess it translates to yours. I'd take it back to factory specs, clean the standpipes/jets, mainly the low speed with the concave top . Another problem make sure your float is set CORRECT. I've been using StaBil marine ( blue ) in my gas , have not had a problem in a year knock on wood- Bob's advice on running it frequently, take that to heart . Sandy Link to comment Share on other sites More sharing options...
Mark Shaw Posted August 1, 2013 Share Posted August 1, 2013 I also suggest you remove the jets with a deep socket and test them for cracks. You can just suck on them with your finger over the end to tell if they have cracks. If so, just solder them and run a drill inside to restore the correct diameter. Link to comment Share on other sites More sharing options...
Dwight Romberger Posted August 1, 2013 Author Share Posted August 1, 2013 Thanks Sandy, Mark, Bob and Leif for all your help. I guess it is time for me to find out if I can take a Marvel apart and put it back together!Dwight Link to comment Share on other sites More sharing options...
Guest outlaw car man Posted August 1, 2013 Share Posted August 1, 2013 Just take you time, not much to these guys. Might consider a permatex type stuff to help reseal. I use a spray carb cleaner out of a shaker bottle to get into the small areas. My guess is the jets ore plugged, if, as it sounds, the Marvel hasn't been apart in your possession. If it's not to gummy, I wouldn't get to deep into it just because of gaskets. Don't break it to fix it ( my motto ) .I've repaired a couple 1933 jet tips by sweating the tips as a plumber does with a pipe. Again, check your float level, has to be perfect. Sandy Link to comment Share on other sites More sharing options...
Marty Roth Posted August 1, 2013 Share Posted August 1, 2013 My 1934 acted that way after a long lay-up many years ago.A good cleaning with carb & Choke spray cleaner (and some areas required a razor) - did the trick. Just be careful not to do any more damage -- slow and easy does it !!Old gas, as we all know, really builds up a layer. Link to comment Share on other sites More sharing options...
Dwight Romberger Posted August 1, 2013 Author Share Posted August 1, 2013 OK. Thanks. I will let you know the outcome.Dwight Link to comment Share on other sites More sharing options...
Guest olympiagirl Posted September 23, 2013 Share Posted September 23, 2013 (edited) Hello, searching for many parts for my step dad and he would love to speak to you about any resources you may have. He recently purchased a 1923 Buick 2 door coupe and he is unfamiliar with the internet. I just signed him up for BCA today also. Edited September 26, 2013 by olympiagirl had personal information (see edit history) Link to comment Share on other sites More sharing options...
Dwight Romberger Posted September 23, 2013 Author Share Posted September 23, 2013 (edited) Hi Ronda,Congrats to your stepdad on the new Buick. You will quickly find out that this is a great place for your stepdad to get assistance with finding parts and advice on his restoration. Most of us are reluctant to give out our telephone numbers as you should be in order to protect yourself from the possibility of unwanted calls. You may also want to remove your email address from the above post for the same reason. (it's the "Dad" in me talking). You can remove it with the "edit post" you will see at the bottom when you click on your post. You can send anyone a private message (PM) through the forum buy clicking on their name, and they can respond to you in the same manner. That being said, I look forward to your posts for your stepdad and maybe this might be a fun way for him to get him on the computer. You may also want to post the '23 Desoto for sale on the Buy/Sell forum.Dwight Edited September 23, 2013 by Dwight Romberger (see edit history) Link to comment Share on other sites More sharing options...
Guest Shoe1932 Posted October 2, 2013 Share Posted October 2, 2013 I also had problems on our '32 -67 with the low speed jets getting gummed up if I didn't drive it for a month. I have had great luck getting the jets unclogged by adding Seafoam into the gas and running the car in the driveway for a while. I have 2 young kids and finding time to pull the carb to clean it is not a great option for me. If it is the jets that are clogged, it will run rough for a while at first but should even out after 15-20 minutes.Good luck and hope it helps Link to comment Share on other sites More sharing options...
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