Model A power

mcorrell

mcorrell

Senior Member
I am finally getting my late grandfather's '29 Model A roadworthy after many minor repairs and adjustments. The car is an older restoration (40 years?) with newer paint. Unfortunately the car fell into disrepair in the late 1990s after my grandfather went into a nursing home. He passed in 2004 and the car then went to my father's barn until last summer when it as given to me. During the the years in storage (at least 13-14 years) I would run it when visiting my father once a year. One year my father left water in the engine and the head cracked. He had a local "guru" replace the head with a stock compression aftermarket head.

All of this leads up to my question, how much power should a good running stock Model A have? How do you know seat of the pants? Since this is the only Model A I've driven I have no other "yard stick" to compare it to.

I took the car out Saturday when the temperature was in the mid 80s. On level ground she ran fine and seemed to accelerate OK, up to about 42 MPH, and that was all she had. When I started climbing a slight grade (1 or 2%) she started getting hot and quickly ran out of power pulling only 30 MPH and dropping fast. I shifted down into second gear and she still was running hot. When I turned her around and went back down the grade she got up to 45 MPH but didn't cool down as I expected, even after backing off to 35 MPH. When I pulled over she was boiling. The radiator seems to be flowing well and she has a new water pump. I think she is just tired. I borrowed a bore scope and took a look at a couple of the cylinders and found evidence of corrosion and scoring (red arrows). I have a compression tester adaptor on the way.

What would be the minimum compression psi for a "healthy" Model A with a stock CR? On a level road, what MPH should a healthy stock Model A be able to maintain?
 

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several things:
!. Timing might be off
2. intake, exhaust, or carb at intake seal to gaskets, snug up the nuts and cap screws.
3. head retorque, head gasket could be leaking.
Bob
 
This may sound silly but did you advance the spark when the engine was running faster? Retarded ignition will give you both poor performance AND it will run hot.

X2 on checking the timing.
 
I agree with others it sounds like a timing issue. Either initial timing is off or you need to get the hang of how to use the timing lever. Also is it possible your carb is running alittle lean? 42 isnt real bad, I know several people who will not go over 35 although their car is capable. Rod
 
Timing is good and adjusted to engine speed/load. Same goes for GAV. I was about 1/2to 3/4 turn out before I hit the grade. Adjusted it open to about 1 to 1.5 turns and moved spark rod from 90% advanced to about 50% at 30 MPH under load. The engine doesn't smoke when idling but does smoke quite a bit when accelerating. The GAV works as it will start to backfire when you get it too lean. Even after a few miles the plugs looked a little oil fouled.
Back in OH where the roads were flat she would do about 42 to 45 w/o any heat issues that we knew of, but we didn't have a motometer.
As much as I wanted to keep her stock I think I am going to have to go with a better carb that doesn't need adjusting on the fly and the same for the ignition advance. The roads in the Smokey mountains change too quickly. I may look for a good used "touring" engine if I want to drive her much. A new or recored radiator would be good insurance.
 
mcorrell said:
I borrowed a bore scope and took a look at a couple of the cylinders and found evidence of corrosion and scoring (red arrows).
Click to expand...

Since it was only getting a yearly run and did a lot of sitting you may have stuck or coked rings in addition to some corrosion on the cylinder walls. A trick I have used for 40+ years, when I get my hands on an old "been sittin' " car is to pull the plugs, shoot a tablespoon of Automatic Transmission Fluid against the wall of the cylinder (don't want it to just pool on top of the piston) and then slowly pull the engine over 2 revolutions. Then I let it sit for an hour.

I have found that the ATF will soften any "gunk" fouling the rings and also act as a momentary mild abrasive to help clean up the walls and re-seat the rings.

I've never ended up worse than I started and have pull off a few that looked like miracles.

mcorrell said:
On a level road, what MPH should a healthy stock Model A be able to maintain?
Click to expand...

"60 mph all day long"
 
I'll have to give the ATF a try. I've used Marvel Mystery oil mixed in the fuel for sticking valves in the past (other cars). I've got a compression tester adaptor which will help me diagnose things better. This car has not seen a lot of use going back to 1991 when my grandfather purchased it. He would bring it out to idle in his front yard an hour or two a week while he sat on the porch.
 
You may be running too rich by opening gav too much. Half to 3/4 for start and 1/4 to run when warm some say to close when on highway.
 
I tired it in a lot of different positions as grade is a couple of miles long. I was told about 1 turn open to start and then 1/2 turn open to run. This will change based on temps and elevation as well as engine condition. As it was hot and at 3000 feet and climbing I was probably a little on the rich side but she was running OK on level ground. Full closed she was backfiring (lean condition) when going downhill at speed (40ish MPH)
Compression and leakdown tests will confirm the overall health of the engine.
The good thing is that I have fixed a lot of problems to get to this point. I still need to rebuild the steering box to cure the 6" play at the wheel. At least the paint, body, and interior are OK.
 
If you haven't located a local Model A chapter you might try to find one around your area. By connecting with them they can give you advice and assistance to get you on the road. If you check MAFCA.com and search for chapters, or MARC.com and look for regions you should be able to find a group close by that can give you some suggestions and help with your project.
 
You have access to a good guy in your back yard. Drive it over to James Rogers place in Leichester and let him diagnose the engine while it is still in the car. You can find his phone number on his web-site.
 
JohnLaVoy said:
If you haven't located a local Model A chapter you might try to find one around your area. By connecting with them they can give you advice and assistance to get you on the road. If you check MAFCA.com and search for chapters, or MARC.com and look for regions you should be able to find a group close by that can give you some suggestions and help with your project.
Click to expand...

Very sound advice given here by John ! Wayne
 
Sounds like maybe your carb may need some work or a rebuild. Also have you checked the points? Do you need new ones maybe? You said you had done a lot of work on it already so maybe you have taken care of these things.

I have 2 stock 1929 model A's. On the level I can get them up to 50 MPH but going up hills they will drop down to 30 or so. Some steep hills I will have to shift to 2nd and I can get up to 30 MPH in second. Both of them after warming up, I will run with the GAV maybe 1/2 or 1/4 turn open and leave it that way for the trip. I will run with my spark lever maybe 2/3's down and keep it that way. I do not have heating problems but do have good radiators. Have one on the huckster that is extra thick, bought it from Bert's in Denver and Steve stated it would never get above 180 which it has not.

Another thing you could consider for touring is to put in a Mitchel 2 speed. This gives you a number of options for going up and down hills. But if you plan on doing a lot of touring, then your ideas of a touring engine would be your best option.

Hope this gives you some answers to your original questions.
 
Here are the best and worst plugs with about 10 miles on them. These pics were taken with the plugs cold and the car sitting for a week. Cylinder number 1 is the best and cylinder number 3 is the worst. 1 and 2 are about the same as are 3 and 4. Yes, new NAPA points and a cleaned and adjusted carb.

I will post compression test results this weekend.
 

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You guys kinda glossed this over, but its very telling here in this diagnosis- "Full closed she was backfiring (lean condition) when going downhill at speed (40ish MPH) "

That sounds more like manifold leak or exhaust leak. If it doesn't backfire on level ground, only on downhill engine braking, that may be an issue. Also, it does sound like a timing problem, and you are probably running with the carb too rich to compensate for the manifold leak.

New manifold gaskets installed properly with clean surfaces is the quick and easy fix for that.

After only 10 miles, the spark plugs don't tell you much. Though that #3 plug says something.

James will likely figure out the issues very quickly for you if you can get the car to him.
 
A Model A from the factory would run 60+ mph. This on the crappy roads of the day.

Properly restored to original you should expect to be comfortable running at 55 MPH and hitting 65 MPH (depending on body style) should not be an issue. Running 55 MPH is not an issue with a stock drive line and you should expect to get upwards 50,000 miles on the engine.

Properly restored is defined as restoring the engine back to factory tolerances with respect to balancing and precision of fit. For a bit more power going to a B cam is a simple change, my opinion is a new cam from Stipe is the most bang for the buck. The cam is the heart of the engine and many are not in very good shape so you are usually in need of something better for your car, so going to a B type grind is a smart use of your money.

Of course this does not help with your problems, but at least lets you know what you should expect. I recommend reading "The Legendary Model A Ford" to get a better perspective to how the cars were driven back in the day and what you should expect from your car today.
 
Kevin, thanks for the information. Having driven this car on/off for over 20 years I can say it has never even sniffed 55 mph. 45 has been tops and it took a while to get there. My grandfather lived in the city so that didn't bother him. For me, the lowest speed limit is 45 for several miles until I get to the nearest town. I'd like the car to be safe and will not be afraid to spend a little to get it there. I just want to be sure the heart of the engine is sound before I started adding high CR heads and such.
 
I wonder if your car is running too cold? or if it ran hotter might help that one cylinder... I have two cylinders like that and installed a thermostat... I will say my car now that it'= running hotter (~180F at the neck with a 1650F stat in the upper hose) an increase of 40F, sounds and runs much better... I cannot say for sure if it would help your car...
 
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