Can't get my m35 over 35 MPH

[panzerbob]

Wanted to get all of your opinion on this problem, My M35 1954 Gass Reo was owned by, what's the best term, an idiot somewhere in its life. When I attempted to bring it home last weekend I could not get it to go over 35 mph. The engine was running well, but it had no power. I am trying to track down the issue, and have two culprits as likely. The first is that he switched the ignition system from 24 to 12 volts. he did put a 12 volt coil in, but would this lead to less power? The next possible issue is he switched the carb to an aftermarket one that I think looks to small for the engine. I can't find any number on it, other than it is a holley 2 barrel job. Definetly not military. My guess is that the carb is too small, and not letting enough air into the engine at load. Just thought I would get all of your opinions before I drop 250.00+ on a new carb.

p.s. Yes, i did make shure it was in high range, and the front drive was not engaged, and the enigne was timed.

 

[DanMartin]

RE: Can

Before chasing ghosts, I would do a full tune-up on it. It's much better to debug engine problems when you have known good parts. Also make sure you have good fuel in the tank (never trust the old stuff).

Hook up a vacuum gauge that you can use while driving (plumb it into the intake somewhere). With the truck going as fast as it will go, and the pedal all the way to the floor there should not be any vacuum (should read close to zero). If there's vacuum, the carb is too small or not opening all the way. Check linkage and make sure you are getting full throttle.

I would also double-check ignition timing (not sure on the gassers, do they have a vacuum advance?). If so, make sure the advance is working and plugged in to the right port of the carb.

Also check that the fuel pump is working properly (can provide enough fuel to keep the carb full).

IMO: Go get the right carb for that motor. From what I hear the gassers are quite peppy compared to a stocker multifuel. Spend a bit of money on new stuff (plugs, wires, cap, the right carb, all new filters, fluids, etc) and you'll have a real runner. You're going to have to do this all eventually anyways...

 

[DDoyle]

RE: Can

This may sound too obvious - but are you certain the transfer case is in high range? Not just the lever, but the transfer case itself. Carb should be something like FFG884 (this is from memory, someone will surely post the real number) and tag is on base.

Regards,
David

 

[panzerbob]

I was wondering about the T-case , how does one verify that it is in high? obviously I worked the lever, I can go from what I assume is high, to neutral, and verify that the truck is not moving, and then into what I think is low. is there a possibility that it is sticking in low even though it is disengaging in neutral? I did check the vacum advance, it is functioning properly, truck has new points, had a tune up last year. The prior owner just used it to move junk around his property, bad terrain so prob never went over 15 mph.

 

[ygmir]

RE: Can

one thing about hooking up the vacuum gauge:
Make sure you are reading "manifold" vacuum, below, or downstream, from the carb butterfly.
Ported vacuum, above or upstream from the carb butterfly, which runs the vacuum advance, grows with throttle opening.......inverse of manifold.
What size is the engine?
I've seen some pretty big engines run on some pretty big 2 bbls.....but, an undersized carb would show up at top speed/load......

A 12V coil shouldn't lead to less power, the spark is many, many volts, as created by said coil........

If all is running smoothly, just weak, then, It would seem to be a fuel/air/timing thing. Assuming compression is good......

good luck,

 

[DDoyle]

RE: Can

You should be able to shift the transfer case while the truck is moving. Were it me, I'd put the transfer in low - drive down the road, making note (or having a helper do it) of the speeds you make each shift, and when you get to the top of fourth gear, low range, for the next shift, shift the transfer case to high range. The ride of the truck on that shift should "feel" like another gear. If it doesn't - then the transfer isn't shifting - and you can compare the shift points you noted with the ones listed in the operator's manual (and on the dashboard instruction plates).

Other possibilities including dragging brakes (either service or parking) - but you should smell that (and perhaps see smoke).

DD

 

[WillWagner]

RE: Can

panzerbob, The t-case lever should be all the way up..toward the seat..for high range, and all the way down at the floor, for low.

 

[acetomatoco]

RE: Can

The governor could be the culprit? However, a replacement carb? Those motors are bulletproof How does it rev in neutral? Are you getting up to 4000 or so? An old timer can tell without a tach!! Sounds like wide open in low range is about the max speed he is reporting.. let us know.

 

[maxim]

RE: Can

Jack up each axle with the truck in neutral and see if each axle will spin freely by hand to rule out a stuck brake. When you throttle in neutral up do the rpms go to its optimum (whatever a gasser would go to, I presume about 2,300). Then when going down the road will it attain it's optimum rpm under load. Do you notice the engine speed increasing without increase in speed indicating a slipping clutch. I know old tractors had weights in the disrtibutor and if they rusted up it did not perform well.

 

[Barrman]

RE: Can

The manual says the Gasser should rev to 3400 under no load. The governor stops it at 3400 supposedly. It is supposed to go to 3200 under load.

There is no vacuum advance on the stock distributor. Yes, there are two "vent" lines hooked to the housing. Air in and air out. Notice how one of the lines goes to the fuel pump for fuel pump venting as well?

A good running Gasser should out accelerate most multifuels and wind out faster on a flat surface too.

Is it making any pinging noises, getting way hot or cutting out? Those are good indications that the timing is way off or the points are out of adjustement. Another weird thing to look at is the point return spring. If it is weak, the points don't get closed fast enough to allow the coil to build up enough voltage to give a full spark. This is a problem on M715's which have the same basic distributor. They wind up great through the gears until you get to 4th and then they just won't go anymore.

Since you didn't mention a loss of power in 5th only, I am more inclined to go with the t-case in the low range diagnoses already explained to you.