VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 39 won't run past ~25 MPH

The 216 in this '39 refuses to accelerate past about 25 MPH. Here's what we have done:
1. New points, condenser (Points set)
2. New coil
3. Rebuilt Carb and adjusted float SIX times.
4. Blow air through gas lines, checked fuel filter and
sediment bowl and filter inside the bowl.
5. Cleaned spark plugs (they were a little blackened)
6. The vacuum advance works @ distributor.
7. Fuel pump produces 7.5 lbs.
8. Gas tank removed and cleaned last year and coated inside to
prevent rust.

BTW, this vehicle has been in the family since 1961 and endured
the driving of four brothers. It has 16 coats of lacquer and new chrome on bumper, grill, etc. We KNOW this vehicle inside and out but it now has us stumped.

It starts and idles fine. It will accelerate okay but then acts like it is fuel-starved or maybe not receiving correct spark. Almost like it has been turned off. It will run
nicely at 20 MPH.

Many thanks for any suggestions or trouble-shooting clues.

Did you use after market points that have only a light brass spring -----which is only a ground....and a stronger actual spring came with the points (unattached) which you failed to install....thus the point arm is floating at speed.

Tom,

I had the exact problem with my 38 last year and submitted the question to the forum. Consensus was either something clogging fuel supply or a problem with the points--neither seemed apparent on the car, but (at Gene's suggestion) I rechecked the point and replaced them with another set that I had--it ran perfectly. Even though you've changed points, it might be worth another try (cheap and easy); it did the trick for me.

Jim

I also support the points being most likely. Could also be the condenser or restriction in the intake manifold. Vacuum gauge will quickly tell the later.

If fuel supply problem it will run faster until you reach the equilibrium between supply and use rate and then level out. Also if you take foot off accelerator, wait a short time, then push accelerator again it will accelerate for a short time then settle back.

Try taking the gas cap off. If that helps the vent is not open and causing a vaccume in the fuel supply.

After all that you only cleaned the plugs? Maybe you should have replaced them.

A restriction in the exhaust system is easy to check by take the exhaust pipe lose at the manifold and driving. You just need to back the nuts off to create a good exhaust leak. A vacuum gage will also tell you that is a possibility if the vacuum drops off at high rpm's, should be about the same as at idle.

If the above advice doesn't help I should try the following
1: Take your air cleaner temporary out see if it drives better
2: Check that you ignition is set properly according to the shop manual it might even be better if you give it another 5 to 10 more degrees of advance.
3: Do a compression test to see if its withing limits.
4: Get a set of good quality plug wires

Jianis

Check your vacuum advance.

My brother says he installed Borg Warner points. He also said he used some sort of extra? spring.

Thanks

I,ve also had a similar problem when the exhaust manifold heat flapper got stuck in the closed position. Good luck, you will get it.

All great suggestions. We'll probably start going through them Monday. We "know" that it is something simple but just can't figure it out. I spoke with my brother on his cell phone and he said he had some other points. At this time I'm willing to clean the old points and try them. If it makes a difference we'll know we are headed in the right direction.

Yes, we probably should have replaced the plugs but it was supposed to start raining and we wanted to adjust the float and do some driving before the rain started. We don't usually drive it in the rain. Also, it's twelve miles to the nearest parts store which may not even have the plugs or wires, etc. Poor excuse but part of living in a small village.

I've printed out all of your suggestions, gentlemen and, again, many thanks (Dank).

Tom

Tom,
I would be inclined to think Chipper is right in that it is a fuel supply problem. Nonetheless check for the following:

a. Sticking speedometer needle. Roll down the window and see how much air is blowing by.

b. Unhook the mobile home.

c. Take it out of low gear. Its amazing what you can get out of second and third.

e. Just accept the fact that 25 was about top speed for a 39.

d. Get a fifth of Jack Daniel, a rocking chair, a 45 (You'll need it for a proper job later), your lap dog. Send your wife shopping with all your credit cards, open a can of peanuts and start rocking. Once you gotten into a pleasant stupor and sufficiently liquored up so you can properly grieve the fact that you don't have a more modern 41 instead of that old "one- off" slow moving 39 go out to the 39, raise the hood and put a 45 round in the side of the block. You may feel better. Maybe not. Such is life.
Charlie

BTW: I'm just a-kidding you. Don't part with your credit cards. Also, given the fact that Gene owns a 39 is testament enough that they are great cars. I'm sure you will figure out the low speed problem soon. Please let us know what you discover as the problem.

Tom, I too had a week spring on a brand new set of points. It was a NOS set (I bought at a swap meet) so I have no idea how old they were? I thought my problem was timing, but the minute I changed the points the "poor power" was gone. When I inspected the points I could see that the spring was not as taught as on other sets of points.

On January 10 Sid posted a question about the manifold heat riser. Here was my response:

You should be able to fix the problem with out removing the manifold. Take a small brass hammer and starting on the end with the heat riser spring lightly tap on the end of the shaft. Try doing it about 10 times then tap on the other end of the shaft next to the heat riser about 10 times. Eventually you will notice that the shaft is moving back and forth about 1/4 of an inch. When it seems that you could almost move the shaft right to left by hand then try turning the riser up and down. This also could be done with a little taping on the bottom of the riser then on the top. Eventually the riser should move easily up and down and you should feel the spring tension wanting to close the riser and keep it closed. If the spring is working then the riser will open when the spring is hot. If you decide to beat on the end of the shaft you will end up flatting the end of the shaft where the spring fits in a groove and it will complicate removing or installing the spring. Reestablishing a working groove for the spring is a bit more complicated. I use an old knife blade to pry the groove back open. If you remember who the Pointer Sisters are then you know about the "slow hand routine" working out best. The riser shaft is not lubricated so friction or the lack of a lot of friction is what keeps the part working well. It probably is a good idea to test your heat riser several times a year to see how it is working. New springs are available from Chevs of the 40's.

There were also other suggestions. Use the Advanced Search with the topic of "heat riser" in quotes to located them.

Good luck, Mike

A friend of mine had a problem similar to this. It ended up being that some of the gas tank sealer was comming off and floating around inside the tank.
He ended up bringing the tank to a radiator shop and they had to chemically strip the gas tank sealer out and flush the tank. If there were problems, they would have soldiered the pin holes or made a leak proof repair. It has been several trouble free years since.

Charlie,
That's FUNNY!

I've entered the Gentleman Jack phase of life though regular Jack also works well. Also, I've never had much luck with a .45 but I think a FMJ from my .40 would do the job.

It's good to start the day with a laugh.

Thanks a lot.

Tom

Mike,

I recall banging on that rascal back when Eisenhower was president.

We'll give it a try.

Thanks

Tom

That's a possibility we have thought about.

My brother removed the tank last Spring and cleaned it. He then put in some sort of rust inhibitor, whirled it around, and let it dry.

IF some of that chemical is floating around the increased suction at higher speeds might pull down the debris and clog the outlet. You'd think we'd find some debris at the sediment bowl?

We'll do the "cheap and easy" stuff first but keep that in mind.

Thanks

Tom

2. New coil

installed properly ( + / - ) & correct voltage ( 6volt - 12 volt )

& i polished the carb " power valve " w / brasso so it slid more freely .


just thinkin............

It sounds almost exactly like the very frustrating experience I had in flint and after I got home. 37 216 would start and run great...for a few miles. After performing all of the above suggestions and then some, including blowing out the fuel line, new coils, points, ensuring carb jets are clear, no junk getting to the carb through sediment bowl or new inline filter just under the tank (pickup truck), the problem is....

Crap in the fuel tank. It wasn't rust or dirt, but something slightly buoyant. This stuff completely block the petcock under the tank. Even with a near fuel tank, once i gained rmp and mph, this junk would get sucked into the fuel shut off, nor reaching the fuel filter. The demands for more fuel would sucks this stuff in, cut off fuel flow, and starve the carb. After sitting, the junk would float back into the tank and the engine would restart and run like a champ...until the engine was fully drawing fuel...and the condition would repeat.

My best guess is the partially buoyant junk is from the fuel sender cork float. The sender needed replacing after a total frame off, including ensuring the tank was clean. Simply draining the tank on more than one occasion didn't clean the tank. The junk would stay clung to the tank and even refiltering the fuel never ensured a clean tank. I need to flush the tank, which may involve complete tank removal.

Sorry, I submitted before editing.

BTW, I have been told that a product like Por-15 can be used to coat the inside of a fuel tank. Haven't tried it myself though.

Another reason I did not use "sealer" in my tank...If the tank isn't perfectly clean ( like new ) when you use that stuff . Bits and pieces can and probably will come off years later...It happened to me...What made it so frustrating is the previous owner did it and I had no idea it was in there...( It wasn't Redkote , it was some Yellow looking snot...)

Mine would "act-up" only at freeway speeds and on long hills...Kevin

Unfortunately the yellow "snot" was made before we had to fight the ethanol stuff. The ethanol would loosen the yellow and therefore the problems.

Your tank must be cleaned of the yellow "snot" and other impurities. To do this you must remove the tank and treat with MEK. This will cut it loose and allow you to flush it out. Once the tank is completely clean you can then recoat with either the Red or the Blue sealer. At that point you will be all set until we come up with some other miracle fuel.

If the fuel line is obstructed it will get up to speed and then the engine will die. IF it gets up tp 25 MPH and keeps going at that speed and just will not go faster like it has a governor its probably the ignition.
If it has a 1939 Carter carburetor it has no power piston to polish.

If there is sufficient fuel for it to maintain 25 on a fairly flat surface then it won't die but keep poking along at that speed. It will slow down when it comes to a hill or grade demanding more fuel to maintain the 25. And, speed up some on downgrade. As there is more clogging, the top speed will gradually decrease.

On modern cars the partially plugged fuel filter will manifest itself this way. I suppose the same conditions could cause the instant 39 to not go faster than 25. I experienced this with a 93 GMC and 76 GMC 1500s.

Gene, all I'm saying is that it can be faults other than insufficiently strong points spring action, thereby causing the points to "float." 25 seems a relatively low speed for the points to float. There may be too wide gap, also. Worth checking out, though.

Now having said that, I can guarantee everyone that it will be the points spring. Dang!
Charlie