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EFV-8 Club Forum / 1940 Ford Discussion / 1940 Flathead Misfire

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Posted By Discussion Topic: 1940 Flathead Misfire -- page: 1 2     trmsr 06-13-2023 @ 11:01 AM reply profile send p.m. Member Posts: 8 Joined: Sep 2021 I have a restored (restorer unknown)1940 (presumably) stock Flat Head that starts right up but then breaks up / misfires badly as soon as it seems to warm up. It has: fresh E0 gas, new spark plugs, NOS carburetor (94), rebuilt fuel pump, and a gas tank that appears recently new. Does anyone have any experience with this problem and or suggestions for probable causes?  kubes40 06-13-2023 @ 11:22 AM reply profile send p.m. Senior Posts: 3425 Joined: Oct 2009 The engine is 1942 - 1948. You state the carburetor is NOS. The carbs were never finished that color, so it isn't NOS. Rebuilt perhaps. I prefer to go at things methodically. From what you describe, it sounds more like an ignition issue than a fuel issue. If it were a fuel issue it would most likely show its ugly face all the time, not after the engine is warm. Me? I'd start by sending the distributor out to Charlie Schwedler in Orchard Park, NY. for a proper rebuild. He's the best in this regard, quite reasonable and prompt. That would eliminate the distributor from the equation. You obviously have a later coil mounted on the inner fender. Typically, those are fairly trouble free. However, I say "typically", not always. I note the 8v. battery. That makes me wonder how many volts you have at the distributor. Usually, an 8v. battery is indicative of issues being covered up rather than repaired properly. The extra volts also make me wonder what it's doing to the coil, points and condenser. While the distributor is out for rebuilding, I'd strongly suggest you obtain a 6v. battery to eliminate any issues the 8v. may introduce. You may very well find that 8v. battery was installed as the engine didn't turn over well when attempting to start it. That's almost always a cheap and fairly easy "fix". Proper battery cable gauge, clean grounds (free of oil and paint and lastly, a properly rebuilt starter will nearly always take care of things. The ground cable to your battery appears to be of a smaller gauge than required. Keep us abreast of your progress and there are those on this site that will help you achieve your goal... a reliable old Ford. Mike "Kube" Kubarth This message was edited by kubes40 on 6-13-23 @ 11:26 AM trmsr 06-13-2023 @ 4:56 PM reply profile send p.m. Member Posts: 8 Joined: Sep 2021 Thank you kubes 40 for that comprehensive analysis and the source reference for the distributor rebuild,  that is what I will address next, along with the return to 6 volts. In regards to the carburetor  I am attaching some close up pictures of what I have.  Also would you please forward a little more contact information for Charlie Schwedler. For ref. before the carb,pump, and plugs were changed the engine was rough at start up would not hold an idle with out lightly pumping the gas pedal so those changes did help but obviously were not the root cause as you have stated.  Just wondering except for the not correct engine year points that would be deducted if the car was being judged, is the 42-48 engine a plus, negative, or neutral?  kubes40 06-13-2023 @ 5:27 PM reply profile send p.m. Senior Posts: 3425 Joined: Oct 2009 If you have the car judged, it is judged against how it left the assembly line. Thus, the incorrect engine is a rather large negative. I am more than willing to help you in any way I am able. I might suggest you purchase the book "It's Ford for '40" from the club. I believe you will find it very helpful. The carburetor is a service replacement part that does not "match" what was factory installed. Service parts were meant to fit and operate but not necessarily match the original part. Charlie is a good man. He can be reached at cas5845@yahoo.com Mike "Kube" Kubarth trmsr 06-14-2023 @ 3:51 PM reply profile send p.m. Member Posts: 8 Joined: Sep 2021 My car is a nice driver.  So judging would not be an issue.  Tom Meyer  (trmsr) This message was edited by trmsr on 6-17-23 @ 2:43 PM RAK402 06-14-2023 @ 7:50 PM reply profile send p.m. Member Posts: 442 Joined: Jul 2015 I purchased this as an N.O.S. carb about seven years ago (also in what appeared to be the original box). I post it for color comparison (I don't know whether it is correct, either). This message was edited by RAK402 on 6-14-23 @ 7:51 PM 40 Coupe 06-15-2023 @ 4:12 AM reply profile send p.m. Senior Posts: 1685 Joined: Oct 2009 trmsr: The Carb is a much newer service replacement but it also is missing parts to make the choke function. Note the empty threaded holes on the side of the Carb. and where does the dash hand choke attach the upper choke plate can flop from open to closed. also is there a place to connect the dash hand throttle? How did you connect the throttle pedal? Instructions you have show some of the missing parts This message was edited by 40 Coupe on 6-15-23 @ 4:22 AM kubes40 06-15-2023 @ 5:48 AM reply profile send p.m. Senior Posts: 3425 Joined: Oct 2009 RAK, The finish on your carburetor appears correct. The cover is from a later model. Without more photos, I can't tell whether or not the remainder of the carb is correct. Mike "Kube" Kubarth trmsr 06-15-2023 @ 7:02 AM reply profile send p.m. Member Posts: 8 Joined: Sep 2021 40 Coupe, The service replacement carb required the use of some of the linkage parts from the carb that is being replaced along with some included small parts to be selected depending on the model year you're using it on. With the correct combination everything works as it should. See blow up of instruction sheet attached. RAK402 06-15-2023 @ 11:42 AM reply profile send p.m. Member Posts: 442 Joined: Jul 2015 One more thing that might cause it to miss (and this is grasping at straws), is the spark plug wires. Very early on (and it is hard to remember, but almost five decades ago) when I first had mine we accidentally swapped two of the spark plug wires on one side (it still had modern, black rubber insulated spark plug wires at the time). It would start and idle for a while (better than you would think), but would become rough. You could feel it when driving (very unpleasant).

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