Top Speed In Your Flattie

[55 Fargo]

Who has gone right out floored top speed in their flathead powered car or truck?

I have not, have driven the old 47 Chrysler to about 70 mph, with more to go.

Today drove the Fargo to about 70 mph, might go 5-10 mph more.

I have 3.23 gears, would think I would top out at about 80 mph or so.

So lets hear it, verified true top speeds you have driven with your current or past flatties.....

[plyroadking]

I took my '40 Plymouth up to around 100 a couple times. The speedometer reads 5-10mph slow and I went to 95-100ish mph on the gauge. It didn't seem that bad but it sure makes anything that's out of balance really noticeable. It takes several miles to get there though.

[DonaldSmith]

My heavy DeSoto Suburban can do 70 or so, if I let it sneak up on me.  Then I wonder why the engine is so loud, and I'll settle down to 60 - 65.  

It's got the 236 c.i. engine and 3.91 differential. 

[JBNeal]

on one adventurous summer Saturday night several years ago, I took the '48 onto I-35 for a 2-mile stretch, got the speedo up to 70 (don't know how accurate that was), and that ol' truck was vibrating through the floorboards something fierce (as most of the original cardboard interior insulation is gone)...it seems more comfortable around 50, especially when stomping on the brakes

 

(FYI that's a stock 230 3spd w/ 4.10 rear)

Edited November 28, 2015 by JBNeal

[desoto1939]

I have had my 39 Desoto up to 65 but I have the 4:11 rear so it is not a high speed rear.  It is a nice cruiser around the 50 MPH mark. Still the original rear end in my 39 Desoto.

 

Rich Hartung

desoto1939@aol.com

[55 Fargo]

Yes anything with 3.9, 4.10, 4.3, gonna be busy at 50-60 mph.

My engine is not busy at 60 mph yet, but the old truck is a bit......LOL

Yes insulation, tires, suspension condition, driveline balance, will all contribute to the ride quality at higher speeds.

I wonder in my case, with 3.23 gears, how an OD trans, say a T5 for example might be. I would think I would be in 4th most of the time under about 55 mph, and needing to downshift against high winds or hills from 5th to 4th.

I do find my gear spread, from 3rd to 4th not that pleasant with 3.23 gears. I still have to take off in 2nd, 1st is way too low even with a 3.23 rear end. Pickup from 2nd to 3rd is nice, 3rd to 4th is okay, once in 4th she is not overly speedy until about 50 mph....

[normanpitkin]

I got my 48 New Yorker up to 85 on the speedo ,probably about 10% out though!

[46Ply]

Well, I had my P15 up to 70+ for the first time today, and she had plenty left, but the car is fairly new to me, and with the Good Year air cushions, it doesn't handle like it might with radials.  Then again, I do have the overdrive!  (which I really like).

[greg g]

My speedo has touched 80 a coupleof times, there is some left but with 4.11's don't want to push it.

[55 Fargo]

My speedo has touched 80 a coupleof times, there is some left but with 4.11's don't want to push it.

Greg are you able to run on the NY Interstate hwys, without too much troubles? Some states it seems no problem, and some it's downright dangerous...

[Don Coatney]

A couple of times I have wound the engine up to 4200 RPM showing 95 on the GPS before I shift into 5th gear overdrive. I have busted 100 a few times but at that speed it feels squirrely. Every bit of free play in the steering and suspension suddenly becomes very noticeable. 

[deathbound]

Hit 70+ with my '38, 201 c.i. engine, stock 3 speed, I think 3.9 rear, original wheels, stock size bias plies.

[55 Fargo]

Hit 70+ with my '38, 201 c.i. engine, stock 3 speed, I think 3.9 rear, original wheels, stock size bias plies.

Hey DB, do you go out onto the freeways around Long Beach and LA area, I hear traffic moves  80-90 mph there now...

[DLK]

My Wayfarer with a rebuilt 230 and a 3.9 rear end will probably cruise all day at 70 but with the old suspension and drum brakes I don't cruise over 65 and off the interstate stick to about 60.

[deathbound]

Hey DB, do you go out onto the freeways around Long Beach and LA area, I hear traffic moves  80-90 mph there now...

 

Yes, but usually just stay in the "slow" lane or the next over to pass. I think people have a little more patience and respect, since it's an older car....if it was a modern vehicle traveling at the speed I normally do, it'd be a different story. 55-60 is a good cruising speed for my car.

[greg g]

I can depending on the number of idiots out and about. I usually run 65 indicated which works out to about 62/3 by GPS.  Prefer the State routes for long runs, But will jump on the super slabs to avoid city stop and go when needed.

[55 Fargo]

Yes, but usually just stay in the "slow" lane or the next over to pass. I think people have a little more patience and respect, since it's an older car....if it was a modern vehicle traveling at the speed I normally do, it'd be a different story. 55-60 is a good cruising speed for my car.

Glad to hear you are "getting a little respect", down there. That's a nice car you have there......

[Desotodav]

I've my blue 52 truck with 16 inch wheels and 4.1 diff ratio up to 75 mph. It felt like it still had a little more to go, but that was fast enough for me!  I suppose that it will do it a little easier when I change the 4.1 diff center over to the 3.54 center I have in the shed!

I've already had a 3.54 diff installed in the 53 coupe truck, so look forward to getting it on the road (next year?).

[55 Fargo]

I've my blue 52 truck with 16 inch wheels and 4.1 diff ratio up to 75 mph. It felt like it still had a little more to go, but that was fast enough for me!  I suppose that it will do it a little easier when I change the 4.1 diff center over to the 3.54 center I have in the shed!

I've already had a 3.54 diff installed in the 53 coupe truck, so look forward to getting it on the road (next year?).

Maybe but don't count on it, engine wil not be as busy, but your suspension, steering and driveline will be.....LOL

[deathbound]

Glad to hear you are "getting a little respect", down there. That's a nice car you have there......

 

Thanks, don't recall anyone giving me the 1 fingered wave.....usually the full hand or a thumbs up.

[soth122003]

I've had my P-15 with a 230 engine in it and original rear end with 15" radials up to 75 maybe 80. (the needle bounces a little). The steering an the suspension let me know to slow down though. Spooky at that speed, it likes to run at 55-60 best.

 

Joe

[BobT-47P15]

A few years ago, when I had some radial tires on the convert, I ran it up briefly on an interstate to around 

70.  It handled fairly well, but was still a bit scary.  This car actually has a 1939 Dodge pickup differential

under it......so geared a bit to the lower side.  I have a Borg Warner R10 overdrive that I need to get

installed.  I don't think I would drive any faster with O D, but the engine would just run easier.  Mine is a

1957 Plymouth 230 engine, bored .030 over.

[Robin (UK)]

I've run mine up to a true 95mph, measured on GPS.
It was still accelerating but I felt that was enough!

[meadowbrook]

My stock 50 with an R7 OD will happily cruise at 75 all day, I have hit 80+ but try to avoid it. With the new springs, radials and shocks as well as allowing lots of following space, it feels comfortable at 70-75.

[TodFitch]

By my GPS, I've had my '33 with its stock 190 cu. in. engine and 4.375 rear end up to 70 MPH. Took a while to get there and couldn't maintain it on a grade. As noted by others for their newer cars, 50 MPH is a lot more comfortable (but I do sit at about 60 MPH or a trifle above if I have to go long distances on a freeway).

 

Hey DB, do you go out onto the freeways around Long Beach and LA area, I hear traffic moves  80-90 mph there now...

 

 

My last few times traversing the LA metro area (in a modern car) leads me to think that the average speed on a freeway around there is closer to 35 MPH than to 80 MPH. Maybe at 2AM it gets up to 80, but not during the more normal times of the day that I've gone through there.