Max Speed of a Model A with 26% OD and HC Head
 

For member with a Mitchell 26% overdrive and a HC Head at 5.5 or 6.1.

What is the max speed you had your car at and at what speed do you feel comfortable at for extended periods of time.

I have a feeling that the max speed will be quite high.

Ron

Re: Max Speed of a Model A with 26% OD and HC Head
 

All I can tell you is that I run sustained 68 mph in my Model A (per Garmin GPS readings) with a standard Model A 3-speed trans. I have 12 volt modern point system, a lightened flywheel, balanced crankshaft, and a Weber Two barrel carb with the modern intake. I also add Lucas lubricates in both the engine and in the trans. I have had enough sports cars to 'know' that it does make a difference.

I am also running 1935 wide-rims and radial tires with a piston stabilizer on the steering and 'float-a-motor' rubber engine mounts front and back – past 55+ the car handles with limited vibration and little perceivable shimmy.

I have read here and other places that I can add an additional 5+ mph if I use a cast iron header exhaust and different muffler system, but have not done that as of yet. I use a four blade fan for cooling here in Florida, but I have also read that the use of a six blade plastic fan will work better and reduce the drag on HP and speed. Another advantage to consider.



Lots of changes that can really perk up the wonderful Model A.

Re: Max Speed of a Model A with 26% OD and HC Head
 

Gear ratios can be deceiving. Just because mathematically it will raise your speed, if you don't have the horsepower, you won't go as fast as you think you can. Pushing a Model A thru the wind is like pushing a barn.

Re: Max Speed of a Model A with 26% OD and HC Head
 

Remember what kind of brakes these cars have. Especially if you’re not using cast drums.

Re: Max Speed of a Model A with 26% OD and HC Head
 

Re: Max Speed of a Model A with 26% OD and HC Head
 

Wayne
I have multiple cars for that kind of driving and regardless of how fast they go I never exceed 5 to 7mph on the interstate. That said I have no intention of ever using my Model A on the interstate. I am interested in hearing what people can attain with 6.1 head and a 26% Mitchell as this is what I will be running. By knowing what the max performance is with an otherwise stock car I am trying to judge an optimum max cruise speed without causing damage to my engine for long distance driving. I do think the best speed for a Model A is 40 to 50mph but secondary roads tend to be 55 to 60 when you get out of town. In my opinion my car is safe at 60 as my steering, brakes, suspension and front end have been refreshed but the engine is turning just a little to fast to hold that speed in my opinion.

I am not trying to build a race car out of my Model A rather make her a little more drivable. I am the kind of guy that would love to drive across the country someday in a car that's pushing 100 years old. I know that may be strange for some but to me that's a great way to get out of work and spend my vacation experiencing Small Town America.

Ron

Re: Max Speed of a Model A with 26% OD and HC Head
 

My 1930 Town Sedan has a 5.5 HC head, standard 3.78 rear end, and a 26% Mitchell OD. The previous owner restored the car and had the engine re-built, so I do not know exactly how well things were balanced. My steering, brakes, and tires are all very good, and I feel quite comfortable doing a sustained 55-60 mph. I’ve never tried running it as fast as it will go....I’ve hit 65 a few times, but 60 is my upper limit for comfortable cruising.

Re: Max Speed of a Model A with 26% OD and HC Head
 

Back in the day my car did 65

Re: Max Speed of a Model A with 26% OD and HC Head
 

Mainly because in a way we are purists.. the ford flathead four cylinder has good torque stock and outstanding 'keep up with modern traffic' torque when modified. It was my desire to prove the basic model a platform relevant in todays driving conditions, to run anytime without the protection of a convoy.

Ford marketed the model a as a car 'to meet todays (1927) demand for speed and comfort'...With modification it still does,90 years later..

Re: Max Speed of a Model A with 26% OD and HC Head
 

PB, what rear end ratio do you have?

Re: Max Speed of a Model A with 26% OD and HC Head
 

I have a 6.1, larger intakes, model B carb with bored out intake, touring cam, lightened flywheel, 26% overdrive, cylinders bored .60 over, electronic ignition, 3.78 rear end.

Very comfortable at 55MPH, 60 is OK but the rpms are getting up there, 65 no problem but it seems a stretch.

Re: Max Speed of a Model A with 26% OD and HC Head
 

I could not have said this better myself. I want my car to appear stock in every way but make minor modifications to keep up with modern 2 lane roads that are posted at 60mph. The modifications alone will not help if your steering, brakes, suspension, and front end are worn out. I share your same desire in your comment about the Convoy.

"It was my desire to prove the basic model a platform relevant in todays driving conditions, to run anytime without the protection of a convoy."

Re: Max Speed of a Model A with 26% OD and HC Head
 

Thanks for the info. I would be happy with 55 to 60 as a max cross country speed. Now just need my Mitchell to come in and a HC Head.

Re: Max Speed of a Model A with 26% OD and HC Head
 

The setup and results are the same on my Pickup.

Re: Max Speed of a Model A with 26% OD and HC Head
 

Without getting into the details of the physics, it takes a certain amount of power to push a car along at any given speed. As the speed rises, the resistance increases till you reach a point where the available power is all used to maintain what is the maximum speed of the car. So long as there are no silly gearing issues etc, O/D or not will not make much difference to the top speed. The O/D does not increase the power available. The HC head makes a bigger difference.
That said, if you want to travel at say, 60 mph, the car is happier with the O/D. Things are not so busy under the hood.

Re: Max Speed of a Model A with 26% OD and HC Head
 

If you want to travel at 60mph you need a V8
you got your new engine yet Arnold.
My shed is full of them
Lawrie

Re: Max Speed of a Model A with 26% OD and HC Head
 

I am not building a hotrod and I do not want to....and besides I hit 62 without a HC Head or an overdrive in a stock car but I would not want to hold that speed for very long. I think the Model A is more capable than many people think when everything is not worn out.

Ron

Re: Max Speed of a Model A with 26% OD and HC Head
 

With stock wheels and tires 62 requires real good roads.. even with 16's and modern radials you have to 'give her her head'.. don't try to hold her on a string, just 'herd' it down the road. Everyone agrees the car is comfortable at 45 no matter how much you do to it.

Re: Max Speed of a Model A with 26% OD and HC Head
 

The model a powerplant will handles a 2.90 or so to 1 final drive ratio,especially if you can split between 3.78 and 2.90 easily..2.90 allows you to keep the engine in its torque band at a higher speed so in essence OD does make a difference in useable,dependable top speed.

Re: Max Speed of a Model A with 26% OD and HC Head
 

My Fordor has an overdrive, 5.5 head, Weber, insert bearings, cam, etc. I have had it up to 70 with more to go but I like driving it at 55. It has excellent brakes and steering so I do not feel threatened at 55 or even 70. The engine HP was estimated at 90 by the builder but I suspect it is more in the 70 range.