How fast should I drive?

[tiquer]

Originally Posted by Colorado Greg

Going that fast on a new engine doesn't sound like a good thing to me. They need to be broke in and have the rings seated before pushing them that hard.
I would check with your engine builder and get their recommendations on driving speed and duration of the break-in.
That being said, a stock Model A is said to have a TOP speed of 60mph. You might get a little more RPM with the counterbalanced crank, but without a grearing change or an overdrive, your not going to get much more speed. It is not a good idea to run the car at top speed for very long. Mine is all stock and it likes to run @ 45mph.
Also make sure you have the brakes to stop if you plan on going this fast!!!

I have found that brakes permitting the counter weighted crank is good for another 1000 rpm over the stock crank . I agree 45 -50 is a good speed for stock , but you should when broke in be comfortable at 55-60.Do not think that a counter weighted crank will make a race engine out of your model A. It only helps to keep down the vibration that hurts the Babbitt bearings at higher RPMs . It boils down to prolonging the life of an A that sees more miles than most week end parade cars. I`m no expert just learn from experiance. My 2 cents worth.

[Del in NE Ohio]

One of the reason I enjoy driving my "A" so much is that I can escape the insanity of the Interstate and cruise the two lanes at 45-47 mph with no white knuckles. Yeah, it'll go faster easily, but my anxiety level is directly proportional to ground speed in modern traffic.

[MikeK]

Based on your rebuild specs, the only limiting factor I see after the first hundred miles and an oil change is the limitation of the dipper-tray oiling. Eventually you reach a point where constant high-speed operation will cause sufficient tray windage to starve the rod bearings. Exactly at what RPM is debatable, but I know guys who run thousands of miles at 60-65 with 3:78 and no O.D.

I'm not one to hold back much on break-ins or agressive running. With modern rings (used in your bowtie pistons) and full insert bearings, after the first 100 mi. I'd let her rip.

The only question I see is are your tires/wheels/balance/bearings, front end, shocks & brakes up to the task? Got seatbelts?

[Bob Johnson]

I did a survey which included touring speeds. See link below.

Bob

Survey Link

[roccaas]

Remember, those tires are put on by hand. How much do you trust them at speed?

[Maclab58]

Sponsored Links (Register now to hide all advertisements)

Have been keeping it down to 45 max. It is such a blast to run around in!

[Marco Tahtaras]

Originally Posted by roccaas

Remember, those tires are put on by hand. How much do you trust them at speed?

The tires are on drop center rims just like modern tires including motor cycles. Additionally they have inner tubes so they don't "blow" like they can on your modern vehicle. It is a "non-issue".

[roccaas]

Originally Posted by Marco Tahtaras

The tires are on drop center rims just like modern tires including motor cycles. Additionally they have inner tubes so they don't "blow" like they can on your modern vehicle. It is a "non-issue".

Marco, do you see any concern with the tire rolling under if you cut the wheel too hard at speed? I saw the results of this on a T Speedster with tall skinny tires, and was warned by a senior mechanic that the bead could slip down into the drop center, the inner tube would "hernia" out of the other side and blow.

[Marco Tahtaras]

Originally Posted by roccaas

Marco, do you see any concern with the tire rolling under if you cut the wheel too hard at speed? I saw the results of this on a T Speedster with tall skinny tires, and was warned by a senior mechanic that the bead could slip down into the drop center, the inner tube would "hernia" out of the other side and blow.

I can't come up with a diplomatic way to excuse the comment from your "senior mechanic", so I'll just have to say not a chance. As far as the Model T goes he was either running early demountable rims or replacement split rims. In either case he did something stupid which would be more like having a Model a wheel come off because the lug nuts were left loose.

The engineering in this area hasn't changed much to this day.

[roccaas]

Senior in the sense that he'd learned his trade on the farm before opening a garage in the 50's. When his "on the axle wheel balancer" finally died we were all saddened and much shaken while driving on smooth roads. He looked like the man in LePages book.

[Shadetree]

Originally Posted by Maclab58

I just put a new touring engine from Antique Engine Rebuilding in my 28. I Have about 300 miles on it now and it runs great but Im a little concerned as to what the top speed that is safe to drive it. I have hit 60 a couple of times on a short burst but the engine seems to have more room to go. Is there a point where I shouldnt push it past? Im new to A's so any suggestions? BTW, stock trans and rearend, the engine has a balanced crank, insert bearing and Chevy pistons and a lightened flywheel.

I remember an old saying. "Break `em in fast and they will run fast"

Shadetree

[V4F]

i have an insert motor also . i run at 55mph , it just seems me & the car are most comfortable at that speed . my car only wieghs #2400 , so wind & ruts will move it around . my car has 3:54 gears & 31" tires . it will run 65mph all day , but my butt tells me its to fast . i do have very good mech brakes , but its where i am comfortable that makes up my mind . 55mph works for me ...................... steve

[bobpo]

My Father-In-Law was recently stopped by the State Patrol for driving 40 mph on a 4 lane for going too slow. (Thank you State Trooper). Later he was stopped for going 15 mph on another 4 lane at midnight headed away from home. Police brought him home that time. Then he scraped a guard rail as he was being pulled over by another police jurisdiction for wavering all over the road. Delivered by Police again.

The most recent, I received a call from State Police 55 miles away asking that we come and get him at 2:30 am, in a snowstorm. (father-in-law was confused). My wife and I got him home at 5:30 am, then went back for his car. We still have it locked up........He's 93.

Bottom Line..Drive what you're able to do but be reasonable and SAFE.

[Peter J]

In highschool I had my 31 coupe up to 70 a number of times and to this day I wonder how I survived given the state of the tires, brakes, steering etc. Not enough A's left to be piling one up.

[MrTube]

These threads seem to pull more arguments and disagreements then oil threads.

I can tell you our stock A seems to be able to do 50-55MPH. Supposedly Henry said they will do 60MPH.

HOWEVER, I can also tell you 50-55MPH feels like the vehicle is pushing the envelope. The engine is much happier at 40MPH. Maybe its due to wear. Maybe its due to a poor rebuild at one point. I don't know.

What I do know is, I can tell the vehicle is not happy at 50MPH.

If you have a balanced crank, high compression head, different cam and different differential gears it probably can easily do 50-60MPH. I would say it depends on the specific vehicle and as others have said even the driver.

If you feel like you can barely control the vehicle and at times the vehicle is driving you, you are going too fast.

[Bob Johnson]

I have found that the weather is what determines how fast I go. With perfect weather my car likes to go 65 mph (with OD). But wind, rain and lack of sunlight all contribute to a slower "comfortable" speed. Since a Model A aerodynamically is a brick with wings strong winds will push it all over the place if you are going fast. So as the wind picks up I slow down. Rain and night time make it harder to see things and to be seen. Unless it is unavoidable I will not drive at night in a rain storm. If I did I would likely prefer around 40 mph.

Bob

[captaincorley]

I saw your blurr come by the fire station, I was too slow to yell at you. Hollar , I would like to see that engine. BC

[Special Coupe Frank]

"Supposedly Henry said they will do 60 MPH."

Indeed, but in 1928-31, how many roads were there where you could drive that fast for more than sprints of a couple miles ?

I think old Henry was making a shrewd bet in terms of marketing... how many people were really able to put that 60 MPH claim to the test ? Again, maybe short sprints... but it was not the same kind of driving as trying to run 60 MPH on today's Interstates for hours at a time.

A properly broken-in, "blue-printed" factory Model A may indeed have been capable of sustained running at 60 MPH, but I wouldn't try it with one of questionable integrity...

45 - 50 MPH feels a lot better, in my experience.

[Maclab58]

Hate to admit it but she seems to like the 45-50 mph the best. put about 100 miles on her this weekend. what a stress reliever!

[RonC]

Originally Posted by roccaas

Marco, do you see any concern with the tire rolling under if you cut the wheel too hard at speed? I saw the results of this on a T Speedster with tall skinny tires, and was warned by a senior mechanic that the bead could slip down into the drop center, the inner tube would "hernia" out of the other side and blow.

Model T's don't use drop center rims. Model T tires will demount if they are underinflated. They should be inflated to 60 psi for the 30 inch tires and around 35 for the 21 inch tires.