Missing out at high RPM

mjdunn

mjdunn

Senior Member
I have a 1939 Ford DeLuxe that runs perfectly at idle and low speed. At about 40 MPH it misses out. I have new spark plugs 3 months ago, a freshly rebuilt carburetor, by Charlie NY, new gas tank and fuel line. It still misses out when I turn on my back-up electric fuel pump. I also put on a new coil from Skip last Aug. I'm running out of things to check. Any ideas? Would too lean a mixture on the gas cause this?
 
Ken, how would I check for that? I just remembered that I have a fuel filter back by my electric fuel pump. I'm going to replace that tomorrow.
 
I vote for "point float". Weak springs on poor quality points. The distributor has to be put on a machine and run up to higher rpm's. Skip or Bubba can test
John
 
One thing that I would do is round up a spare distributor and get it done up,then it always an easy task to swap the list out and rule out that for problems..
Lawrie
 
Pretty common when a engine idles and runs good then picks up a miss when rpm is increased.
The older single band points dont like a lot of rpm and typically will bounce at 3000 or so rpm.
Be glad to test it and add to the story here on the forum......
 
Bubba, I'm in Indy today. I would like to bring the car to you. I sent you an e-mail with my cell phone number.
 
mjdunn said:
Bubba, I'm in Indy today. I would like to bring the car to you. I sent you an e-mail with my cell phone number.
Click to expand...

You are welcome to come by the shop, however we dont have the time to actually fix the car as we are getting ready for the swap meet etc.
Come by and we can listen to it at the very least . We can check the ignition if its off the car for you....

We are in Speedway across the street from the 500 track at 1330 main street....
 
Well mjdunn came by the shop today and we looked at the car . wasnt missing while we had it in the parking lot. Had a new built charlie from ny carb and a very stock looking ole distributor with condensor. Drivers side cap showed a large gap between cap and housing ( not good) and distributor could be the oldest part in system. Couldnt help him as our schedule was pretty tight and the hoosier swap set up is tomorrow....
A distributor change would more than likely fix the entire deal........maybe monday???
 
I put new spark plugs in yesterday, just in case. It did not help. I will deliver my distributor to Budda's on Monday. As I drove back to my cabin from Bubba's it got worse. Still drivable but uncomfortable. Jim, I may see you at the Swap Meet. I plan to stop by there on Friday afternoon, if I have time.
 
I took my distributor to Bubba's Hot Rod Shop, in Speedway, IN, and he rebuilt my distributor. It runs perfect now. I highly reccomend Bubba's for distributors. Excellant service and he knows what he is doing.
 
As Paul Harvey would say heres the rest of the story:

We looked at the car last week , pretty nice 39 Ford Sedan and looks like Mike drives it a bunch. He drove to the shop from the Lexington Ky area and thats a ride by its self. Distributor looked pretty typical , oily taxi tested tough stock unit. Engine was missing at highway speed. Has a new Charlie carb and Skip coil.
He brought the distributor back monday morning for a closer look on the bench.
Points were pretty much burnt up and fiber rubbing blocks were very dry . One set of contacts didnt have the washer and cotter pin and was moving up and down!!!
Total degrease, glass bead , install new cs47 contacts soaked in marvel and lubed ....aligned new point sets and adjusted on the tester running. Measured rotor for wear and checked side clearance with terminal caps. Ran on tester to verify case timing to engine and shipped it out the door.....:eek:
 
We were sent points from a customer to install before we set up the distributor on the Sun machine. All four sets were tested, and only one was usable. All came from a national source. Some had shorted insulators on the screw connectors, others had badly misaligned points that couldn't be bent into place, among other deficiencies such as poor rubbing blocks and pivots, as well as weak springs. Carefully inspect all point sets before installation.
 
supereal said:
We were sent points from a customer to install before we set up the distributor on the Sun machine. All four sets were tested, and only one was usable. All came from a national source. Some had shorted insulators on the screw connectors, others had badly misaligned points that couldn't be bent into place, among other deficiencies such as poor rubbing blocks and pivots, as well as weak springs. Carefully inspect all point sets before installation.
Click to expand...


Yep pretty common, on the single contacts we use nothing but CS47 Napa units and even then they sometimes need aligning after installation..
 
Some more story with Mikes 39 Ford. Seems he drove the car another 300 miles and it ran perfectly! Then ( dont ya know it?) it started running very bad. He was driving thru Indy and brought the distributor to the shop. A quick test shows the distributor is perfect settings just the way it left here 300 miles ago.
This time i had the coil and condensor. A quick test of the condensor shows .10 mfd or almost shorted !!!!
We rigged him up one of the new Vertex units and sent him back for another ride. Maybe we will hear from him next week sometimes. Seems as if he really drives this car a ton !!!
 
This is our Vertex condensor with case mount, not orginal but never seen a defective unit .....
 

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