Doug&Deb Posted February 2 Report Posted February 2 I know this has been covered before but I’m having trouble finding it in the tech archive. I’m having a low to midrange stumble with my 52 Coronet. Can anyone point me in the direction to diagnose this? The carb is a Stromberg BXVES that has been rebuilt in the last 1000 miles with ethanol resistant parts. Thanks. Quote
Ivan_B Posted February 3 Report Posted February 3 What's going on, you press the pedal but it ain't going? Or something else? Check the accelerator pump and float level. These two things, alone, probably take care of the many carb issues. Quote
Doug&Deb Posted February 3 Author Report Posted February 3 It runs but at lower speeds it runs ragged but smooths out at higher speeds. It’s weird because it ran great last weekend but I’ll check the accelerator pump and float. It’s a starting point and that’s what I needed. Thanks! Quote
Ivan_B Posted February 3 Report Posted February 3 That might be a different issue. Are we talking about idle or driving? How about the engine temperature? Did you do anything to the car before it started running poorly? Could be even non-carb related Quote
desoto1939 Posted February 3 Report Posted February 3 could it be choke issue sticking? just a thought. Rich Hartung Quote
Doug&Deb Posted February 3 Author Report Posted February 3 I haven’t done anything recently. The idle is fine. I’ll start with the basics. I haven’t looked at it yet. I used the car to run an errand last night and noticed the problem. I’ll get into it this weekend. Rich I hadn’t thought about the choke sticking. I’ll add that to my list. Quote
Los_Control Posted February 3 Report Posted February 3 How about the gas tank? Last week I had to change the carb on my project truck, I had a spare. The carb had several hours of run time but not actually driving it yet. As a project I have been running on a temporary 2 gallon with no lid, just a hose stuck in the top. Dirt has got into the carb and will need to take it apart for a good cleaning. TBF I also need to make the permanent fuel line and has no fuel filter. I just think a dirty carb could be the sign of a deteriorating fuel tank .... or possibly dirty fuel from the last gas station you filled up at. Also what kind of fuel filter do you have? I currently have the glass bowl with no filter inside it, will add a modern filter under the vehicle near the tank when it is time. Various reasons why the carb can have dirt in it, I think pulling apart the carb to clean the passages was fairly common on these old cars. Not so much today. With better filters and tighter restrictions on gas stations .... unless the problem is on your end and in your tank. I would remove the carb from the car, then in a drain pan I would wash it down with carb cleaner so would not transfer any dirt from outside into it. Then disassemble the carb paying close attention to the idle circuit and using carb cleaner and compressed air blow out all the passages .... rinse and repeat and get it all as clean as you can and then reassemble it .... hopefully you should not need any new parts as new as it is. I then would change all filters in the car and throw in a can of seafoam in the tank ... A poor attempt at cleaning the fuel system while you are at it. Naturally if the tank is bad, it will happen all over again until that is remedied. Quote
Los_Control Posted February 3 Report Posted February 3 As a side note, sometimes it is difficult to distinguish between ignition and fuel problems. IIRC, If your points are wearing and no longer opening far enough, could cause your issue. Idles fine but stumbles picking up speed .... enough spark for idle but not for under load. Quote
Doug&Deb Posted February 3 Author Report Posted February 3 Los, the tank is new as well as the filter but I’m still going to check for dirt first. I recently had my dwell meter hooked up and everything was fine. Still things to check though. Quote
Frank Gooz Posted February 3 Report Posted February 3 I have had trouble with my 1950 Dodge,BXVES and it turned out to be a bad carb to intake gasket. Good luck Quote
greg g Posted February 3 Report Posted February 3 (edited) How old is your fuel pump. Some have an internal debris screen might be plugged. I had a chunk of rust on the inlet fitting. It acted like a ball valve. It would let enough gas to flow to support idle, gentile driving up to 30 to 35, but when flow peaked it would close up and choke the flow, drop back to 30 it was fine. Worth the time to pull the pump and check it over. Also worth doing a vacuum gauge diagnostic before you tackle other stuff. Go to secondchancegarage.com for a good vacuum gauge tutorial. Intake manifold vacuum should give you a reading of 21 inches, and steady needle at 450 to 500 rpm idle. Edited February 3 by greg g Quote
Ivan_B Posted February 3 Report Posted February 3 (edited) 2 hours ago, greg g said: It would let enough gas to flow to support idle, gentile driving up to 30 to 35, but when flow peaked it would close up and choke the flow, drop back to 30 it was fine. I believe that the author is experiencing exactly the opposite symptoms ? Edited February 3 by Ivan_B Quote
Doug&Deb Posted February 3 Author Report Posted February 3 Greg I’ve never gotten above 17 inches on the vacuum gauge no matter what. My vacuum port is on the intake manifold behind the carb if that makes any difference. I’m going to dig into it tomorrow. I did take a quick test drive and it still stumbled until around 50 mph then it’s fine. No power pulling a hill through. I do have a 2nd carb. If nothing else I can switch fairly quickly to see if that helps. Quote
Los_Control Posted February 3 Report Posted February 3 3 minutes ago, Doug&Deb said: I do have a 2nd carb. If nothing else I can switch fairly quickly to see if that helps. NO NO NO!!! Thats cheating ? Thats what I did, I needed to clean out or go through my original carb ... same time I ordered a rebuilt from rockauto. So I went through the original and put it on the shelf for a spare, and was running the one I bought from rockauto. So it was really simple to swap out and try it last week. I now have a different problem with my accelerator pump not working. But the original problem I was trying to figure out went away ..... So I know it is a dirty carb in my case .... my spare needs a accelerator pump. Might get a bad rap for not going through proper troubleshooting procedures .... sure is nice having spare parts though ..... I also have known good working spares of my ignition system. Quote
Sniper Posted February 3 Report Posted February 3 59 minutes ago, Doug&Deb said: Greg I’ve never gotten above 17 inches on the vacuum gauge no matter what. My vacuum port is on the intake manifold behind the carb if that makes any difference. I’m going to dig into it tomorrow. I did take a quick test drive and it still stumbled until around 50 mph then it’s fine. No power pulling a hill through. I do have a 2nd carb. If nothing else I can switch fairly quickly to see if that helps. Altitude will affect that level. I am at about 1600 feet and I can get 21" no problem. https://www.motor.com/magazine-summary/mastering-the-basics-reading-a-vacuum-gauge/ Here you can see my vacuum level Quote
Doug&Deb Posted February 5 Author Report Posted February 5 As the saying goes 90 percent of fuel problems are ignition. I checked the fuel system and even installed my other carb. No luck. I also have a second distributor although not technically correct for my 52. That solved the problem so I’m going to install some tune up parts in the original distributor and see how that goes. Thanks for all the advice. 1 Quote
greg g Posted February 5 Report Posted February 5 Thanx for re prooving that automotive parable. What is the difference between your distributers? My 56 Plymouth engine in my 46 bizcoupe runs a 54 dodge pickup distributor. When I looked up the differences, it was just slightly massaged advance curves. Advance got more aggressive as compression ratios went up. I chose the truck unit cuz it best matched its specs when spun up on an old Sun tune up machine. Glad you found your solution. Quote
Los_Control Posted February 5 Report Posted February 5 I just learned in the past month or so that in 1949-1950 the trucks had 2 different distributors available. I actually have to use the number off the tag in order to get correct parts for it. Not saying I have the wrong dizzy for my truck, just that they had different options and they used different sized caps, points, rotors. Just saying. Quote
greg g Posted February 5 Report Posted February 5 On vacuum, my 46 pulled 19, had a lot of blow by. My rebuilt 56 230 pulls 19 but it has duel carbs. Gauge attached to the windshield vacuum port. My friends rebuilt 51 pulls just over 20 with single carb. On distributors, I have 4 each 2 were IGS, 1 was an IAT, cant remember the other one without a trip to the parts cabinet. But I did post a picture here years ago highliting the differences. One had a high body and a short distributor Cap, one of the others had a lower body casting, with a taller cap, rotors were different, points were different and one had the points mounted on the opposite side of the breaker cam. All reasons to get tune up parts by the number on the tag. And a compelling reason to pull the dist out to address any issues. 1 Quote
Doug&Deb Posted February 5 Author Report Posted February 5 Greg my other distributor is correct for 49-50. I forget the number but the correct one is the IAT4011. Both work equally well. All I need to do now is adjust the points gap. My dwell is 28 and should be 36-38. That’s what I get for using a feeler instead of my dwell meter. Quote
greg g Posted February 6 Report Posted February 6 Match books are getting hard to find these days... Quote
Booger Posted February 6 Report Posted February 6 3 hours ago, greg g said: Match books are getting hard to find these days... Damn you are so old school! Quote
greg g Posted February 6 Report Posted February 6 Well, I started school in 53 so in fact most of the schools were fairly new. Elementary was built in 51. Quote
Booger Posted February 6 Report Posted February 6 (edited) Back in the day (geezer) we 'tuned' these old cars by ear. Dwell meter? Vacuum gauge? Turn the dizzy just so much. Play with mixture screw. And dont use Champion plugs These are not Ferraris Edited February 6 by Booger Spel Quote
Sam Buchanan Posted February 6 Report Posted February 6 5 minutes ago, Booger said: Back in the day (geezer) we 'tuned' these old cars by ear. Dwell meter? Vacuum gauge? Turn the dizzy just so much. Play with mixture screw. And dont use Champion plugs These are not Ferraris Stop advancing the timing just before the engine pings while pulling that steep hill on the way to grandma's house................. Quote
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