Engine Loses Power on Hills - UPDATE in this Post
 

I'm working with a Model A friend whose engine is losing power when the car is climbing hills. Runs well on level roads.

I haven't yet touched the car, but I'm trying to think of possible causes. Here are three that perhaps could make the list:

1. Something floating in the gas tank that obstructs fuel flow on uphills.
2. Partial gas line obstruction that restricts fuel flow enough so that the engine can't get enough gas in high demand situations.
3. Float level issue.

Do any of these make sense? Are there other possibles that I should put on the list?

Here's the update:

The car is a '29 Tudor converted to a 12v system; engine rebuilt several years ago. Here's what we found and did:

1. Worn/misaligned points; replaced and set gap.
2. Yellow spark; replaced condenser.
3. Spark plug gaps and condition fine.
4. Timed engine.
5. Weak fuel flow; car has an ancient shutoff valve and no pencil filter - deferred replacement as parts were not on hand.
6. Discovered advance/retard arm not able to fully retard; it was half-way between full retard and advance with the driver lever fully up. Straightening linkage rod helped but didn't fully cure this issue as the arm doesn't quite reach fully retarded position.
7. Re-timed engine with advance/retard linkage disconnected and arm in fully retarded position.

We test drove the car after steps 2, 4 and 7 and noted improvement after 2 and 4. But the car still performed poorly in our view. It wasn't until we realized that there was an issue with the advance/retard arm, addressed most of that, and re-timed the engine that the car came back to life. It now gets up hills in 3rd gear that it had trouble negotiating in 2nd at the start of the process.

Here's our theory/guess about this car: With restricted fuel flow and timing effectively retarded, the engine was working from a real deficit. This is the only A that the owner has driven, so the report that it was "running okay" likely wouldn't have felt okay to a more experienced driver. So what happened on the way home from the tour when the car suddenly started having trouble climbing hills? Something pushed that poor engine over the edge - we're guessing that it was the points, perhaps in combination with the condenser, that did the job on an under-fed, poorly timed engine.

The fuel flow issue still needs to be addressed; doing so should further improve things.

Thanks to all of you who offered suggestions - much appreciated.
Dave

Re: Engine Loses Power on Hills
 

is he using his spark advance correctly? can another model A make it up the hill just fine?

does it just loose power or does it start coughing/backfiring?

Re: Engine Loses Power on Hills
 

My rule of thumb is start with the basics, timing, point gap, and plug gap.

Re: Engine Loses Power on Hills
 

Thanks for the suggestions, both of you. Plan is to check the easy, simple stuff first....starting with driving it (up hills) so I can see first hand how it behaves!

Re: Engine Loses Power on Hills
 

New all of a sudden problem or long standing problem.

If not a new problem how worn is his engine. Perhaps do a compression test.

Re: Engine Loses Power on Hills
 

We recently had a member in our club with the same issue. After checking all the basics multiple times, he finally discovered that the valves were way out of adjustment.

Re: Engine Loses Power on Hills
 

Did he or someone install one of the micro filter units in the gas inlet to the carburetor?
I installed on my coupe and on the first long hill I lost power because it would not pass enough gas. I quickly took it out.

Re: Engine Loses Power on Hills
 

I had a similar problem. It was timing. On my 31 Slant Town Sedan, the steering column bolt at the steering box had broken allowing the steering column to turn in it's seat on the steering box due to vibration while driving. This changed the geometry of the spark advance (and throttle) levers to where the hand lever would not move enough in the spark retard direction. Basically, spark too advanced for the steep hills I was climbing. Once I replaced the broken bolt (which secured the steering column and allowed proper range of motion for the spark lever) and properly reset the timing, my car now runs up those hills without a problem when I adjust (retard) the spark.

Re: Engine Loses Power on Hills
 

What is his diff ratio? A high ratio will make hill climbing difficult.

Re: Engine Loses Power on Hills
 

Thanks for adding to my list of things to check!

This problem started last summer on the way home from a tour. Previously the car had run well. So something has changed......the challenge is to figure out what!

Re: Engine Loses Power on Hills
 

Hmm probably not this since it was ok now its not but make sure noones installed extra thick floor material so the throttle doesnt actually open all the way.

All good suggestions so far as well, did the problem come on instantly on the tour or was it over the course of several days?

Re: Engine Loses Power on Hills
 

Sure sound like the problem caused by the fuel line extending too fasr into the carb inlet. The end hits the horizontal screen filter and restricts flow into the tube. Quick and easy check.

Re: Engine Loses Power on Hills
 

Check for a hot blue spark, as a weak spark will show itself first on hills.

Re: Engine Loses Power on Hills
 

More good ideas! Thanks, everyone. It'll be like having the entire Barn there helping me Friday. :) I'll report back and let you all know what I found.

Dave

Re: Engine Loses Power on Hills
 

I second modela mike's suggestion in post #6 --- adjust the valves.

Jim

Re: Engine Loses Power on Hills
 

I would go with Tom Ws suggestion # 13, the big clue from Pilot Dave states something went wrong on the way home from a trip.

Re: Engine Loses Power on Hills
 

I had the same problem and tried everything listed. Then l heard from a reputable source that a certain engine rebuilder whose engine I had was having problems setting valves. We set the valves and the problem went away.

Re: Engine Loses Power on Hills
 

valve problems are assuming the valves are adjustable, right?
if they are not adjustable the only thing to do if they are a problem is put new adjustable ones in??

Re: Engine Loses Power on Hills
 

All are adjustable. The original valves and lifters need to be adjusted by grinding material off the stem if they are too tight, and removing material from the seat and/or valve face if they are too loose.

Re: Engine Loses Power on Hills
 

I sure wouldn't tear into the engine until it was confirmed the valves were out of adjustment. If they are too loose, it will be "clacking" quite a bit. Too tight and a compression or leak down test will show it.

I really doubt if it is a fuel delivery problem. If there isn't enough fuel being delivered under load to keep the float bowl filled, it will start running badly under load, but as the float bowl empties further it will stop running. If it just runs badly (no power) it could be the carburetor (dirty, plugged jets, throttle not opening fully), but I too would suspect ignition.

In any case, before you start taking guesses and replacing parts or doing major work, I would suggest diagnosis.