640 Idles Perfect but Won't Rev Pp

Just thought I'd pass along this experience below on to others, and the simple solution, lightly sand your points before installing them.

Repairing a 1954 Ford 640 for a neighbor, it sat for 15 years in a field after its owner passed away. The gas tank was shot, so I removed it and installed a 1 quart push mower tank with fuel filter to keep working without spending too much money, till I was sure all was good. Eventually put in new carb,points, condensers, rotor, cap, wires, plugs, alternator, gauges, battery, wiring, oils (steering, trans, steering, PTO, rear end) and got everything working great. Drove it around for a while, when I saw everything was perfect, I went ahead and put in the new gas tank. THEN all hell broke lose. The engine would not run above 800 rpms.

THEN all hell broke loose: the engine still idles perfect but it will not rev up, it'll spit stutter, even sometimes backfiring, but it won't speed up. I had forgotten to let some fuel run through the hose and into a container to clean out the hose before installing it on the carb, so I figured maybe something got into the highspeed jet. So, I took apart the carb and cleaned all the orifices with Isopropyl alcohol 91% and a injection syringe, then used compressor air and all was spotless, though I didn't find any trace of dirt (the carb is new). I put everything back together and tested and still same problem. I disconnected the air breather to carb connection and tried it again, no change. I again hooked up the 1 quart temporary gas tank with filter and it changed nothing. I checked the distributor points and cleaned up the points with Iso alcohol and re-set the points with the dwell meter and put everything back together. No change, still won't speed up. Everything happened after I changed the tank, but it is not the tank. Crazy!!!

ANSWER: My son reminded me that this happened once before to us, when we installed new points on another piece of equipment, that it worked great, then like a few minutes later, it would not rev up. He said that per Taryl Dactal (Youtube personality) we sanded the points in place and cleaned up with Isopropyl alcohol and Q-tip to get any dust. So, we now did just that and the engine and it runs perfect again.

Just thought I'd pass along the experience on to others, lightly sand your points before installing them.

Dirty, oily feeler gauges used to set the point gap can add it the problems with the contacts having coatings on them. I just clean the contacts with a folded-up dollar bill, a piece of card stock, piece of a brown paper bag, or if the points came in a box, use a tab from the box, etc. No sanding or filing new points for me, those processes can wear away some of the contact surfaces, speed transfer of material between the contacts, and may leave grit even with cleaning. Just my method and opinion.

Yes, you are correct, cleaning with cardboarb as you recommend is what we used to do when I had points on my boat engines back in the 1970's. Been a long time and I had forgotten, but curiously, last night I remembered that I think we used a piece of the points box or a matchbook. This morning I check the forum and see that it is that way. Thanks for the reminder, that is the proper way to do it.

God Bless

Spoke too soon, the engine returned to its old ways idles perfect but it will not rev up, it'll spit stutter, even sometimes backfiring, but it won't speed up. Tried the old set of points and it did the same thing, it runs great for like 5 minutes then goes back to the spit and stutter at high revs. Looks like cleaning the points causes it to run good again, but only a few minutes. Tested the condenser (Made in China) with a multimeter and it failed.

Went to NAPA and they gave me a NAPA/Echlin FA66 which fits perfect (the mounting bracket even has the two dimples that fit the distributor on either side of the mounting screw) and passed the condenser test right there at NAPA.

Installed the condenser and ran the tractor around the fields for 10 minutes and all is well. Hopefully that is it.