Model A highway speed.
 

First, let me apologize for my ignorance. I never thought I had any problems with my Model A except when a cop friend of mine told me that if I planned to drive it on the highway I needed to be able to travel at least 45 mph.

So one day I pulled out onto the highway and got near 45 before it backfired loudly and stalled out. This happens every time I get around 40 mph. I did notice that the engine sounds like it's taching at a high rate.

So just how fast should a model A run?

Re: Model A highway speed.
 

45 mph would be a good speed..The only problem here in NJ is all the traffic lights and stoping distance needed to stop the A comfortable.
I stay on back roads and feel the A is more comfortable at slower speeds like 35 mph .
I just do not want to have to do a panic stop with A on Highways and have a accident.
Have fun and look at your timing ,points and condenser for your backfiring.

Re: Model A highway speed.
 

only time i checked my car...254 miles, 21mpg, just about six hour trip..so 42-43mph average. Included a stop for gas. Blew the muffler off, spark plug backed out at the beginning and fiddled the timing a bit other than that..uneventful trip.

Re: Model A highway speed.
 

It sounds like your fuel flow is not sufficient to supply the carburetor at high speed. Check the sediment filters ( firewall and carburetor) for cleanliness, the shut off valve for clogging, fuel tank for sediment in the outlet, and that the ferrules on the gas line are no more than 1/8th inch from the ends. An A should travel easily at 45-50. And yes, your brakes should be in tip top condition if you're going this fast, which is possible on a Model A contrary to the urban myths.

Re: Model A highway speed.
 

The fastest I have been is an indicated 67, and have driven all day at 60-65, on the way to a show my brother was following in his modern car, when we got to the show he asked me how fast I was driving -I said 50, he had to go 57 to keep up, but I think his speedo has more error than mine.
My car is basically stock, the only change is a "B" cam.
I do have working shocks, without good shocks my car is not comfortable at 45, with shocks it is stable at 65

The totally stock sedan my father had would do 65, the un-restored sedan my brother had would get into the low 60s

Re: Model A highway speed.
 

Yep, did all that. I also rebuilt the carb and re-timed the engine. It runs great except when it gets up there in speed.

Re: Model A highway speed.
 

Is your carb linkage allowing you full throttle opening??
Paul in CT

Re: Model A highway speed.
 

Something to keep in mind.

When the car was new off the line it was designed to run 60 MPH. Please do not believe me you can find this written in the service letters that you can buy reprinted.

I have never known anything else as my brother, Kurt in NJ, has had his car on the road since 1970. As a little kid riding in the rumble seat I remember the speedo up around 55 MPH all the time.

To get a good historical understanding of the car I recommend reading The Legendary Model A Ford and Know Your Model A Ford (which was reprinted in another book I learned recently). The Legendary book talks about people buying the A and driving them all over the place setting speed records.

It has been my experience that an A with the mechanical parts properly restored to Factory specs will give you the 60 MPH. You will feel comfortable running the car at those speeds and know that you can stop.

Re: Model A highway speed.
 

I agree with Pat.. It appears you have a fuel flow issue or maybe the GAV isn't open quite enough.. Does the situation change at all if you play with the spark lever or GAV ??

Re: Model A highway speed.
 

Never thought about that. I'll give it a try.

Re: Model A highway speed.
 

When I rebuilt my carb, I forgot to put the GAV seat in. It ran up to 40 and then would go no further. After puting the seat in, the GAV had an effect on the engine and would then go to 60+ if I wanted it to.

Re: Model A highway speed.
 

When you lean it out with the GAV to go faster, make sure you do not tighten it down tight or it can damage the needle.
See how playing with the spark lever helps you as you drive along, drop it down and see how your speedometer reacts.

Re: Model A highway speed.
 

I have been carrying my GPS along to check the actual speed. It gets up to 45 easily but due to the fact that I don't quite have my 500 mile "Break-In" yet,I have kept it at or below 45 mph. It purrs like a Kitten at those speeds. It also rides like a dream. It does however seem to like checking out both sides the uneven roadways out here in the country, so I have to keep 'er in check. Tweaking the steering will correct that I think.

I did my very First Car Shows yesterday. One at a Tractor Supply and the other at an old Airport "Fly-In". Couldn't believe how many compliments I got, questions I had to answer and the pictures that people took. I have to tell you, it was Great.

I have decided to call my car "Tillie" named after my youngest son Matt (Matthew). Was going to call it Matilda, but he frowned on that idea, so "Tillie" she is. He's the one I bought it from 2 years ago on Father's Day.:p:p:p:p:p:p:p:p:p:p:p:p:p:p:p

Re: Model A highway speed.
 

I had mine at 50 MPH today and it was driving with no trouble at all.

Marc

Re: Model A highway speed.
 

I am not an expert on these things but I think the ideas put forth above about the carb could be your problem. It sounds like it is not getting the gas it needs. Do you have another carb you could put on it to check?

I find I do not want to drive much more that 45 MPH. The car just seems to "purr" at that speed. Plus I don't care to go any faster in a Model A that is 80 + years old with 80+ technolgy-brakes, shocks, steering, etc.

Re: Model A highway speed.
 

Rakkasan- I had the exact same problem. Under 45 MPH no problem. Turned out the gas tank was full of debris, therefore not enough fuel flow at higher speeds. Solution was to remove the tank and clean it thoroughly, etch it inside, and coat the inside with two coats of alcohol/ethanol proof sealer. Allowed to dry one month before using , repainted it and never had a problem since.That was 15 years ago.

Re: Model A highway speed.
 

My thought is points bounce, If the points have a weak spring and with the cam traveling at such a high speed the points can bounce missing a lobe. This was reported a couple of years ago with the foreign made points ( I think they all are now).

Re: Model A highway speed.
 

Yesterday on my way home from "Back to the 50's", I stopped by a club member's house to fix his Model A, which was doing the same thing. The fix was easy........I removed the fuel line from the sediment bulb to carb, and removed the teflon tape he had wrapped on each end of the gas line. The teflon tape was also covering much of the gas line opening.

Re: Model A highway speed.
 

Another thing to watch out for is the line itself. Some of the repop lines have the ferrule crimped back too far. The line should only extend past the ferrule about 3/32 of an inch or less. The one on my car was so long that it dented the screen in the carb causing a poor fuel flow and vapor lock at times.

Re: Model A highway speed.
 

The backfire sounds like an indication of fuel starvation.

Might also make sure the cap on the gas tank is indeed a vented cap with three little holes drilled through the inner cap, and not a radiator cap ( no vents at all).

My wheezy high-mileage (86,000 mile) '28 coupe will crank-out 55-60 MPH (according to the speedo ) on level road...