My model A wont go faster than 40-45

[Sparta]

Hey guys! I’ve got a bone stock 1931 ford model A. It has a rebuilt engine with steel valves and bearings instead of Babbits. I just out on a rebuilt carb trying to solve the issue, which solved my backfiring issue, but car is still sluggish. The previous owner mentioned that the timing was off and that he fixed it before selling me it. The idle isn’t very steady, meaning it has intermittent hesitations when idling. Other than that, what else could it be? Could timing being alittle off cause the car to top out at 40?

Thanks

[1931 flamingo]

Have you tried re-timing it??
Paul in CT

[J Franklin]

Does it have a 4:11 rear end? Does the throttle open fully for sure?

[Sparta]

I dont know what gear ratio it has...and I’m not sure if throttle is fully open. I can check if the linkage is allowing it to open entirely.

No, I haven’t tried retiming it. Perhaps it’s worth a shot?

[Joe K]

Originally Posted by Sparta

Hey guys! I’ve got a bone stock 1931 ford model A. It has a rebuilt engine with steel valves and bearings instead of Babbits. I just out on a rebuilt carb trying to solve the issue, which solved my backfiring issue, but car is still sluggish. The previous owner mentioned that the timing was off and that he fixed it before selling me it. The idle isn’t very steady, meaning it has intermittent hesitations when idling. Other than that, what else could it be? Could timing being alittle off cause the car to top out at 40?

Thanks

Yes on timing as likely the problem.

Timing the Model A is a little bit of and "acquired skill." Primary to remember is keeping the engine motion "forward" always to take up any lost motion in the moving parts.

From your descriptor, I take it you haven't had the pleasure yet? You really should. Follow the directions which appear in several placed on the Internet, and in several books.

After you get the engine to what you think is "the magic spot," (top dead center) and have moved and fastened your cam, a check you can make is to use the spark advance lever. With the ignition ON move the advance lever to the fully advanced condition (lever all the way to to the bottom.) THEN without having moved anything in the engine, move the spark advance lever up to the fully retarded position. As you near the top of travel in a quiet garage you should hear the points open and the sound of the spark. The closer you can get this to happen at the fully retarded (top) position, the closer you are to correct timing.

Having someone hold a screwdriver on the distributor cam in the direction of rotation (CCW) will help make this check consistent - there is some tendency for the motion of the points traveling around the cam to pull it slightly and introduce lost motion. Not too tight on the screwdriver lest it undo the distributor cam screw.


Anyway, give timing a whirl. It's not that hard.

Joe K

(I have done this check myself by moving the connector lever on the side of the distributor rather than at the steering column. But two people can do it if one is at the driver's seat.)

[30 Closed Cab PU]

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Start with the basics. Basically a tune up. Usually a good idea to do on a vehicle that is unknown, new to you. The hesitations you mention might be tune up needs.
Pull check/clean/gap plugs.
Check/clean/adjust Points gap.
Check that at full spark advance the distributor upper plate arm is against one side of the Distributor body opening, and at full retard the arm is against the other side of the distributor opening.
With spark set at full retard, check/set timing via the timing pin method.
Remove throttle linkage at the carb, manually exercise the Throttle plate - check it is free and goes completely open and closed. Re-attach linkage and insure it goes completely closed to completely open via the foot pedal.
If the vehicle is a pickup, it is possible it may have a 4.11 rear end, which reduces top speed. Typically cars do not have a 4.11 rear end.


Depending on your experience level, at this point you may want to find someone with experience help you. Start with the basics, so they can be ruled out.

[31Tudor]

I would probably check for a nice steady, consistent flow of fuel to the carburetor. Try opening up the GAV on the carburetor and see if that picks up speed. May be running to lean on that.

[Jacksonlll]

Remove your fuel line from carb, and make sure the ferrule is no more than a 1/16 inch from end of tube. If too long, it will hit filter and block a lot of the fuel flow. Easy to check. Good luck.

[J Franklin]

Originally Posted by Jacksonlll

Remove your fuel line from carb, and make sure the ferrule is no more than a 1/16 inch from end of tube. If too long, it will hit filter and block a lot of the fuel flow. Easy to check. Good luck.

If it is a fuel problem it would be bucking and popping I think. Cars that were sold in hill country also had 4:11 gear sets.

[Benson]

deleted info about speed ...

Marshall,

I agree with your recent decision!

[rotorwrench]

A lot of little things can add up to a larger problem. Even if I know who rebuilt an engine, I still wouldn't take condition for granted. I'd make sure it has good compression on all four cylinders. Shake the distributor body and the shaft several ways to see if there is any looseness. Cast iron carb bodies stay pretty straight on the flange over time but the aluminum body Tillotson types can warp & cause a vacuum leak. Any carb can have a loose throttle shaft that will cause a vacuum leak. Loose intake manifold?. All these things can cause up and down rpm fluctuations. Someone already mentioned the GAV rod control or choke/high speed mixture valve control. The mixture can be adjusted at speed but it's a pain to reach over there while driving to do this. Adjusting the timing is not too bad a project once you get the hang of it. The points have to open at the right time or it will be a slug a bug. I just follow the Ford procedure to adjust timing and synchronize the spark control so it can be properly retarded for starting then advanced for running.

Pull the engine through with the hand crank to make sure it has no bearing issues. With no spark plugs installed, it should pull pretty easy. Valves may have been changed to stainless steel from the original steel type stems. I prefer the old steel stems or at least a bronze liner in the guides with stainless type stems. The SS stuff likes to gall if the clearances are too close. You don't need any sticky valves for sure.

[Gary WA]

Throttle Control Linkage may be bent! check easy things first!

[woofa.express]

Originally Posted by Sparta

Hey guys! I’ve got a bone stock 1931 ford model A. It has a rebuilt engine with steel valves and bearings instead of Babbits. I just out on a rebuilt carb trying to solve the issue, which solved my backfiring issue, but car is still sluggish. The previous owner mentioned that the timing was off and that he fixed it before selling me it. The idle isn’t very steady, meaning it has intermittent hesitations when idling. Other than that, what else could it be? Could timing being alittle off cause the car to top out at 40?

Thanks

Just remember Sparta there are more lies told about the size of fish caught, even bigger lies about the ones that got away, more lies told about the yields of crops and lies told about the speed of Model A's. cheers, gary

[whirnot]

The intermittent miss at idle can be timing that is more advanced than necessary for idle. It should smooth out if you retard it some. But being sluggish sounds like it is too far retarded. I concur look at your timing rods first for full travel, set the points, then time it. Rember point gap affects timing as well.

[woofa.express]

Question to you gurus.

This might be the thread to ask a torque question.
My tourer had torque, it could almost be shifted to top at walking pace. I have replaced the spark plugs with new, the smaller diameter thread type with an adapter spacer. It is correctly timed and correctly gapped but lost much of that torque. A shift on the advance/retard lever makes no difference. I notice the gap in the old plugs is much bigger than the new.
Question. Would this gap be the cause of reduced torque.

[40 Deluxe]

Originally Posted by woofa.express

Question to you gurus.

This might be the thread to ask a torque question.
My tourer had torque, it could almost be shifted to top at walking pace. I have replaced the spark plugs with new, the smaller diameter thread type with an adapter spacer. It is correctly timed and correctly gapped but lost much of that torque. A shift on the advance/retard lever makes no difference. I notice the gap in the old plugs is much bigger than the new.
Question. Would this gap be the cause of reduced torque.

Throw the old plugs back in and see if the power comes back.

[Mike V. Florida]

Originally Posted by Sparta

Could timing being a little off cause the car to top out at 40?

Thanks

Yes, that; point gap, movement of the lower plate, and use of spark lever all can effect top end.

[Brad in Germany]

Check to make sure that your coil polarity is correct.



I had a similar problem and it turned out that the coil polarity was reversed. Once I had switched the wires on the coil, the engine ran like a Swiss watch.

Brad in Maryland

[woofa.express]

Originally Posted by 40 Deluxe

Throw the old plugs back in and see if the power comes back.

Hi Deluxe. Well of course, that would be a simple and effective test wouldn't it. thanks, gary

[ronn]

time to buy a race horse.............

[Patrick L.]

How does the car act at 45 ? Any bucking or backfiring, etc ?

[Bob Bidonde]

Try this:

[burner31]

Have you tried a steeper hill?

[mike657894]

I've had similar issues. Are you useing e10 fuel? I get a 30% power drop after warm up with e10. I think it boils in the hot carb. Get a nurex wrench or get good at test light timing. check compression. run your car for a while let it idle does it run worse over time or stall out after 30min and not want to restart. if so check plugs for water wet from bad head gasket. check for flow. bad flow should allow you to run dry in 2nd gear. ride in second and see if it will rev up to max rpm or does it get close then sputter and pop and bog. GPs the speed to get the exact number you are going. I had gps 45 with a bad head gasket and leaking intake. I now gps 55 and some more work to do.

[Humperhill]

Before you start fooling with carb, you should make sure the timing is correct.

[40 Deluxe]

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Originally Posted by Humperhill

Before you start fooling with carb, you should make sure the timing is correct.

Your timing is set by that there lever on the left side of the steering column. Push it too far up, and engine temperature rises while power drops. Pull it too far down, and power drops while the engine pings and begins to self-destruct. Timing is all in the driver's hands!
All that fiddling with the timing pin, distributor cam, test lights, etc. merely sets the initial timing at TDC or slightly after, so the engine doesn't kick back if hand cranking it. As soon as the engines starts and you pull the spark lever down (even a bit) that carefully done initial setting is gone!

[30 Closed Cab PU]

Originally Posted by 40 Deluxe

Your timing is set by that there lever on the left side of the steering column. Push it too far up, and engine temperature rises while power drops. Pull it too far down, and power drops while the engine pings and begins to self-destruct. Timing is all in the driver's hands!
All that fiddling with the timing pin, distributor cam, test lights, etc. merely sets the initial timing at TDC or slightly after, so the engine doesn't kick back if hand cranking it. As soon as the engines starts and you pull the spark lever down (even a bit) that carefully done initial setting is gone!

X2, I agree.


Though setting the timing Henry's way along with all of the other maintenance things (cleaning plugs, right range plugs, carb in good shape with flow tested jets, rotor gapped, points clean and gapped, etc., etc.) incrementally add up to a well running car. Sometimes being fussy has its rewards. The car will run without doing all the fussy things, but may be hard to start, not idle well, poor gas mileage - basically not run perfectly.


This has been my experience being relatively newer to the hobby with my truck. Others with poor running As have asked me what I've done, and the above info is my answer.

[chrs1961815]

Although fuel has been discussed, nobody has mentioned making sure that all of the screens in the various fuel filters (in the tank, in the sediment bowl, in the carb) are clean.

[DHZIEMAN]

Mine will do about 48, but my concern is stopping the darn thing!

[Purdy Swoft]

Originally Posted by DHZIEMAN

Mine will do about 48, but my concern is stopping the darn thing!

Sometimes slack in the brake rod adjustment will cause the brakes to be poor . There is more to brake adjustment than tightening the adjustment wedges .

[Patrick L.]

Originally Posted by DHZIEMAN

Mine will do about 48, but my concern is stopping the darn thing!

Yours will only go 48 ? There is something wrong. They should cruise nicely at that speed, but, should go faster than that.

I understand your concern about the brakes. These brakes are pretty good when set up right but don't stop like a newer vehicle at the higher speeds.

[Purdy Swoft]

Timing is probably the reason that the car won't go any faster than 45 MPH . I first check and adjust the points with a gap of 20 to 22 thousands . When the timing pin drops in place , adjust the distributor cam so that the TRAILING edge of the rotor tip points exactly at the number one contact in the distributor cap body with NO clockwise backlash-rotational movement in the clockwise direction after the cam screw is tightened . Initial timing is very important . . Backlash in the distributor usually causes the timing to be too retarded . I feel that if you can make these exact adjustments you will be surprised at the power and speed your model A will have .

[DHZIEMAN]

Originally Posted by Purdy Swoft

Sometimes slack in the brake rod adjustment will cause the brakes to be poor . There is more to brake adjustment than tightening the adjustment wedges .

Yup! Currently, front drums are off and being replaced, Also brakes shoes are some kind of lubrication soaked. Have front replacement parts and am awaiting cooler weather as garage is just too hot to deal with for me at my age. Anyway, you are right, lots of stuff to make sure of with mechanical brakes and proper adjustment. It will all come together when the temps cool a bit.

[DHZIEMAN]

Originally Posted by Patrick L.

Yours will only go 48 ? There is something wrong. They should cruise nicely at that speed, but, should go faster than that.

I understand your concern about the brakes. These brakes are pretty good when set up right but don't stop like a newer vehicle at the higher speeds.

As I mentioned in another post on this thread, front brakes are in work. Once that is done, will get into timing and carb stuff. Timing on these old rascals done right is not just like tossing on a computer and making some light come on saying all is well. After the brakes, gonna get into timing. I feel pretty sure it is off a bit.

And if I can get the brakes to stop it better, it sure will get me more interested to work at increasing top end speed.

[ryanheacox]

I know you said the engine was rebuilt but if retiming, points adjustment, checking throttle linkage etc. still won't get more speed out of her I'd say check compression.


Ford advertised a top speed of 65 and I think you should be able to at least get close.

[big job]

No ignition timing will correct a cam gear off a tooth, there has been a lot of talk about
'mis' stamped (the dot) repros across the pond gears. Last cam gear I bought has 4
dots ??? whats that a guessing game, pick a dot and hope its a good dot. I'm just
saying it happen'd to me not to mention 4 failed V8 guides within 500 miles on a fresh
59A and we pay them with genuine green backs & we get total melted rice burner junk...

[lildave]

Dwell, how are the points? If the spring is worn the timing becomes erratic at higher rpms.


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[Railcarmover]

all kinds of potential reasons you car will only go 40 to 45 mph.There are sure fire ways to increase speed,but it costs money...how fast do you want to go?

cheap-fast-reliable..you can only pick two.