crazycars Posted September 28, 2015 Share Posted September 28, 2015 Recently resurrected a very solid, original '24 DB sedan. Car runs pretty well but only with the choke control pulled about 60% out. I have checked for vacuum leaks using carb spray around the intake and the carb with no success. The only noticeable speed up in rpm's when sprayed with carb fluid is around the heater (?) tube coming from the lower portion of the carb into the block. I notice that my carb seems to be missing a flange or cover which would surround the tube with the adjustable shutters and lay flat where the tube enters the block. Anyone out there had any experience with this car? Advice would be greatly appreciated.. Link to comment Share on other sites More sharing options...
22touring Posted September 28, 2015 Share Posted September 28, 2015 If I may hazard a guess, it sounds like you've got your metering rack set too lean and you need to richen up the basic mixture. Link to comment Share on other sites More sharing options...
crazycars Posted September 28, 2015 Author Share Posted September 28, 2015 Will give it a try. Thank you! Link to comment Share on other sites More sharing options...
nearchoclatetown Posted September 28, 2015 Share Posted September 28, 2015 The tube you speak of is the air intake for the carb. The air is heated by the exhaust manifold. I agree with the suggestion on the rack. HAve you had the carb apart recently? Or what caused the rack to be out of adjustment? Link to comment Share on other sites More sharing options...
MikeC5 Posted September 28, 2015 Share Posted September 28, 2015 Here are some tips on adjusting the carb. Also search on Dyke's Automobile and Gasoline Engine Encyclopedia, page 178. Link to comment Share on other sites More sharing options...
GaryP65 Posted September 28, 2015 Share Posted September 28, 2015 This is great info! but what if you can't start it. How do you know how bad things are? I did all the required tasks for a car that sat for who knows how many years and I finally got spark but notice that:A - I can't get gas to stay in the tube leading to the vacuum tank (yes I primed it) and....B - It leaks from the tube attached to the motor (have a replacement gasket just haven't installed it yet). Even if I change it, I'm not sure it's getting gas into the cylinders. Link to comment Share on other sites More sharing options...
nearchoclatetown Posted September 29, 2015 Share Posted September 29, 2015 CHEAT. Take the pipe plug out of the top and fill with gas. BUT fix the leaks first. Link to comment Share on other sites More sharing options...
GaryP65 Posted September 29, 2015 Share Posted September 29, 2015 I did, see A. Float works, new gaskets too. Link to comment Share on other sites More sharing options...
JACK M Posted September 29, 2015 Share Posted September 29, 2015 Another cheat, can you squirt a little gas into the carburetor? Link to comment Share on other sites More sharing options...
cahartley Posted September 30, 2015 Share Posted September 30, 2015 (edited) Recently resurrected a very solid, original '24 DB sedan. Car runs pretty well but only with the choke control pulled about 60% out. I have checked for vacuum leaks using carb spray around the intake and the carb with no success. The only noticeable speed up in rpm's when sprayed with carb fluid is around the heater (?) tube coming from the lower portion of the carb into the block. I notice that my carb seems to be missing a flange or cover which would surround the tube with the adjustable shutters and lay flat where the tube enters the block. Anyone out there had any experience with this car? Advice would be greatly appreciated.. Notice in MikeC5's post adjusting the knurled screw is backward from most carburetor idle settings.You turn the screw OUT to lean the mixture and IN to make it richer........gotta think backward....... Edited September 30, 2015 by cahartley (see edit history) Link to comment Share on other sites More sharing options...
MikeC5 Posted October 3, 2015 Share Posted October 3, 2015 When you say you can't get gas to stay in the tube leading to vacuum tank do you mean from gas tank or tube from intake manifold? There should be no fuel in the latter tube (vacuum only). If you get fuel in the vacuum tube it probably means the needle valve is stuck open and carb is flooding. I would tackle one thing at a time. To get the motor started, pour gas into the vacuum tank as mentioned above (a half cup or so). If it won't start then work on carb problem before moving on to vacuum tank. Have you removed the fuel bowl cap to check condition of float and needle valve? It could be flooding. If you unscrew the little cap on fuel bowl cover you can check the needle valve action. With fuel being supplied to carb, pull up on the needle. It should be in down position and move up when pulled if needle/float are working correctly and the fuel bowl is filled (but needle valve could still leak internally causing flooding). If needle is already in up position then fuel is not getting into bowl or float/float weights have a problem. A minor drip on the line from vacuum tank to fuel bowl should not prevent starting. If mixture is way off because of rack/pinion, knurled knob adjustment or the dashpot/metering jet piston being stuck, it may not start. Once engine is running, if vacuum tank can't pull fuel it will most likely be a blocked or partially blocked fuel line (you did thoroughly clean out fuel tank?) or a vacuum leak somewhere along the line to fuel tank. It could also be the vacuum tank check valve is malfunctioning. Good luck! Link to comment Share on other sites More sharing options...
crazycars Posted October 4, 2015 Author Share Posted October 4, 2015 Here are some tips on adjusting the carb. Also search on Dyke's Automobile and Gasoline Engine Encyclopedia, page 1My carburetor, a Detroit Lubricator, is somewhat different but appears to operate pretty much the same. I followed the instructions shown here and got nice results. One thing confuses me however; isn't this adjustment really the same as just pulling the choke cable out to get an even idle?Thanks BTW for your help! Link to comment Share on other sites More sharing options...
cahartley Posted October 4, 2015 Share Posted October 4, 2015 Essentially yes.The choke really isn't a "choke" at all........it simply opens the main jet needle to flood the carburetor. Link to comment Share on other sites More sharing options...
MikeC5 Posted October 5, 2015 Share Posted October 5, 2015 (edited) Cold engine mixture enrichment is the slightly more technical phrase. The fuel/air ratio needs to be larger for cold starting. This can be done by adding more fuel and/or taking in less air for a given amount of fuel.... The Detroit Lubricator uses the former method. When you close the choke on a more conventional carb (with a choke butterfly valve) it decreases the air entering (and the higher vacuum condition in the carb pulls more fuel through the fuel jet. At least that's how I understand it. Edited October 5, 2015 by MikeC5 (see edit history) 1 Link to comment Share on other sites More sharing options...
crazycars Posted October 5, 2015 Author Share Posted October 5, 2015 THAT makes sense! After adjusting as per the instructions, the engine runs as it should. Very happy with the results. Thanks to all! Link to comment Share on other sites More sharing options...
GaryP65 Posted October 5, 2015 Share Posted October 5, 2015 This all great stuff.... for cars that run! Link to comment Share on other sites More sharing options...
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