cbosman1 Posted February 13, 2009 Report Share Posted February 13, 2009 I am working on my dads 53 Plymouth Hydrive Belvedere that has a random hesitation just off of idle that I can't seem to figure out. The mystery is that it doesn't do it all the time. Sometime you step on the gas and it just feels like its going to stall instead of taking off. It is a stock flathead 6 that has been rebuilt and it has the stock Carter B and B carburetor on it that I rebuilt with a kit. The throttle shafts do have some play, so I'm assuming the random hesitation is most likely from vacuum leaks that may come and go as the shaft moves. Any suggestions on a better replacement carb for it? I'm not looking to make this a hot rod engine, just a nice reliable ride. The carb does have a dashpot on it for the hydrive, will I get into stalling trouble if I put another style carb on it without a dashpot? I have put an electronic ignition on it and checked that it has good/smooth timing advance, as well as putting an electronic fuel pump and fuel regulator on it. I even checked the vent tube on the tank to make sure it wasn't creating a vacuum at the tank. Any suggestions on other style carburetors that are recommended or any other suggestions on where to look for this hesitation would be greatly appreciated! Chuck Quote Link to comment Share on other sites More sharing options...
greg g Posted February 13, 2009 Report Share Posted February 13, 2009 The first suspect is likely the accelorator pump. the B & B has three settings for the linkage the bottom on gives the longest stroke andthe most enrichment. Sot if it is not in the bottom linkage hole you might want to move it to that setting and see if it improves the situation. Did you soak the new acc pump plunger in oil when you did your rebuild. this makes them more pliable and thus more compliant for better sealing along the walls of the piston cylinder. You can check for vacuum leaks by using an unlit but open propane torch. pass it by suspected vacuumleak sources, with the car at idle. If you pass by a leak the propane will be sucked in enriching the fuel mix and speeding up the idle. In 54 the carb changed to a Carer bbs (or maybe bbr) one is a 2bbl and the other is a single. but these were a lower carb which allowed hood lowerig along with different air cleaners. However the B and B is so simple and reliable I would check all the above before considering a swap. The other thing to check is your timing setting as it can cause a hesitation if its off at idle. But I still think the most likely culprit is the acc pump circuit. With the air cleaner off, work the carb likage from idle to WOT with the engine off. You should be able to see a steady stream of gas shooting across the air horn section fo the carb. If its sparatic or week, check that acc pump. Quote Link to comment Share on other sites More sharing options...
cbosman1 Posted February 13, 2009 Author Report Share Posted February 13, 2009 Thanks, I'll take a look at the acc pump. I can't remember which hole it is in. I didn't soak the pump before installing it so I'll check the squirt to make sure it is good. I did notice the hesitation seemed to hit at a different spot sometimes when I adjusted the timing. I'll have to double check it, but I think the last time I set the timing at about 8 degrees where it ran the best. Are these engines known to have a hesitation with to much or to little initial timing? Quote Link to comment Share on other sites More sharing options...
claybill Posted February 13, 2009 Report Share Posted February 13, 2009 timing sounds way too adv, but i think it is the accelerator pump...check for a fuel spray as you look down the carb throat while you pump the throttle linkage ENGINE OFF! if ther eis no gas stream..then it is the acc. system HOWEVER, MANY REBUILDS FORGET TO LOOK INSIDE THE BRASS PLUG. if you look at the side of your carb you will see2-3 brass plugs. from the factory...areas you wont or shouldnt mess with. but the one by the acc pump needs cleaning!! you can easily pry this plug out with a sharp knife, take out the jet/ball/spring or whatever , before it falls out. and blow it clear. then pop the parts and plug back n..and look for the fuel spray etc etc. Quote Link to comment Share on other sites More sharing options...
RobertKB Posted February 13, 2009 Report Share Posted February 13, 2009 What's the old quote? Most carburetor problems are ignition related. If you do not find anything wrong with the accelerator pump, check all things ignition, starting with timing. Quote Link to comment Share on other sites More sharing options...
mackster Posted February 13, 2009 Report Share Posted February 13, 2009 What's the old quote? Most carburetor problems are ignition related. If you do not find anything wrong with the accelerator pump, check all things ignition, starting with timing. This is my first time hearing this saying. I love it because it is true. . . I had so much problems with the carb I fix all my ignition components. (and it worked!) Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 13, 2009 Report Share Posted February 13, 2009 I also believe your problem is the accelerator pump. But your timing is advanced way too much. Back it off to about 2 degrees advance. Quote Link to comment Share on other sites More sharing options...
Cpt.Fred Posted February 13, 2009 Report Share Posted February 13, 2009 this thread is great, don't stop! another mistake i probably would have made when rebuilding my BB carb... Quote Link to comment Share on other sites More sharing options...
Jim Saraceno Posted February 13, 2009 Report Share Posted February 13, 2009 I've rebuilt two carburetors for my car. I never knew the "soak the accelerator pump in oil" trick and both times I had severe hesitation in the beginning. Luckily, after sitting for several weeks the pump expanded and the problem fixed itself. Quote Link to comment Share on other sites More sharing options...
greg g Posted February 13, 2009 Report Share Posted February 13, 2009 I believe the factory timing is TDC a bit of advance is good for todays gas formulas but 3 to 5 BTC is probably a better setting. Quote Link to comment Share on other sites More sharing options...
claybill Posted February 13, 2009 Report Share Posted February 13, 2009 does anyone know what the - B AND B - stands for? B&B? ball and ball. name of something or is it about the way the carb works? bill Quote Link to comment Share on other sites More sharing options...
Normspeed Posted February 13, 2009 Report Share Posted February 13, 2009 I set my timing at 4 degrees btdc. On the accel pumps, in addition to soaking in oil, I believe the instructions also say to roll the edge of the pump outward with your fingers to give it a slight flare, for a good fit in the barrel. Not too much, you don't want the edge rolling over when the pump is working. Quote Link to comment Share on other sites More sharing options...
cbosman1 Posted February 13, 2009 Author Report Share Posted February 13, 2009 Thanks for all the great replies. I don't live near my dad but will be seeing him (and the car) in the next couple of weeks and will check the acc pump and brass plug. About the timing, I had is set at the 3 to 5 degree range and it seemed a little sluggish. When I set it between 6 and 8 degrees it had noticeably more power and even seemed to idle better. I revved it and even lugged the motor to make sure it didn't have any pinging. Is it bad to run this engine that far advanced if it seems to like it and it isn't pinging? I would also like to get some new replacement springs for the distributor. Does any one sell them? Quote Link to comment Share on other sites More sharing options...
greg g Posted February 13, 2009 Report Share Posted February 13, 2009 As long as its not pinging, you should br good to go. To advanced timing usually makes itself know by hard hot starting. You can also achieve a good timing setting by using a vacuum gauge connected tot he windshiled wiper port. Setting the timing to achieve the highest steady reading usualy does the trick also. Speaking of distributors, check the wire that takes the circuit from the coil terminat to the points. These will sometimes wear the insulation and ground against the dist body as the breaker plate move in regard to advance. ad also from years of flexing strands can break under the insulation causing insufficient current flow as the strands separate with movement. So once again carb problems might be in the electrical system........ Quote Link to comment Share on other sites More sharing options...
cbosman1 Posted February 14, 2009 Author Report Share Posted February 14, 2009 Thanks. I actually went with the pertronix electronic ignition. However, I'm pretty sure someone messed with the weight springs before we got it. I was hoping to replace just the springs but haven't found anyone selling them yet. Is there a way to test if my springs are right? With a timing light on it, it advances nice and smooth and returns when you let off the gas. Are there specs to tell how much advance I should have at certain rpms? Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 14, 2009 Report Share Posted February 14, 2009 Are there specs to tell how much advance I should have at certain rpms? Most any good service manual (such as a MoTors Maunal) will have the specifications you are looking for. I am away from home and do not have my books to look it up. Quote Link to comment Share on other sites More sharing options...
Jim Saraceno Posted February 14, 2009 Report Share Posted February 14, 2009 I'm looking at a MOTORS right now. It has spring tensions for the breaker arm but not the advance. It does have specs on both centrifugal advance and vacuum advance. If you don't have a MOTORS, give my the distributor number and I can look it up for you. AND if you don't have a MOTORS you should get one along with the service manual. They are cheap and have tons of great info. One more thing about running the engine too advanced is I believe it will make the engine run hotter. As far as ping, has anyone ever got their engines to ping? I didn't think it could be done at these relatively low compressions and today's higher octanes. Quote Link to comment Share on other sites More sharing options...
greg g Posted February 14, 2009 Report Share Posted February 14, 2009 Mine will ping if the timing is too advaced but it has at least .040 off the head/deck. Quote Link to comment Share on other sites More sharing options...
Normspeed Posted February 14, 2009 Report Share Posted February 14, 2009 Chuck, one other thing to consider. These cars will run at their best when fully warmed up. The choke mechanism helps to make them start and run better when cold, but until the motor is really up to full running temp you might get some stumbling on initial acceleration. A quick test drive of a few blocks or even a mile will not really warm the motor up. I can drive mine 2-3 miles before the temp gauge reads where it should, and I don't believe the motor is even fully hot even then, based on the way mine runs after 5 or more miles. Give it a good long drive and see if it still stumbles. Quote Link to comment Share on other sites More sharing options...
cbosman1 Posted February 14, 2009 Author Report Share Posted February 14, 2009 Thanks for all the great advice, it has been a great help! Yes, the hesitation is more noticeable when it's cold and that is understandable. However, it sometimes will randomly start to happen even after driving around for a half hour and it's all warmed up. My dad is going to check into the accelerator pump today and let me know what happens. The distributor number is IAT-4104. Any specs you have on it would be helpful the Service manual only gives us the full advance spec. I have the Factory Service Manual but haven't heard of a Motors manual anyone know the best place to pick one up for a 53 Plymouth? Quote Link to comment Share on other sites More sharing options...
Jim Saraceno Posted February 14, 2009 Report Share Posted February 14, 2009 I don't see any 1AT-4104. 4101 maybe? Any way, this is what I have for early 50's Plymouths. Hope it helps. BTW, MOTOR'S come up on Ebay on a regular basis and for reasonable prices. I have one that covers '35-'53 and another that covers '53-'60. Quote Link to comment Share on other sites More sharing options...
cbosman1 Posted February 14, 2009 Author Report Share Posted February 14, 2009 Jim, Thanks for copying those specs. I did get the distributor number wrong ( I was in a hurry) it is a IAT-4101. I'll start checking for a Motors book as well. Quote Link to comment Share on other sites More sharing options...
Jim Saraceno Posted February 15, 2009 Report Share Posted February 15, 2009 Here is some more good information about checking advance mechanisms. http://www.imperialclub.com/Repair/Lit/Master/001/cover.htm Quote Link to comment Share on other sites More sharing options...
cbosman1 Posted February 15, 2009 Author Report Share Posted February 15, 2009 Jim, That is a great resources. And it's written for dummies...I like that. Thanks! Chuck Quote Link to comment Share on other sites More sharing options...
Jim Saraceno Posted February 16, 2009 Report Share Posted February 16, 2009 There is a whole bunch of great publications over at the Imperial website... http://www.imperialclub.com/Repair/Lit/Master/001/cover.gif Quote Link to comment Share on other sites More sharing options...
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