Driving on the freeway

[Wiggles]

Hey guys!

I recently picked up a 52 f1 pickup with the original flathead and 3speed column shift which had been sitting for a long time. After rebuilding the usual stuff its now roadworthy and is running better and better as I drive it around the neighborhood. Gradually driving it further and further from home over the last few days I finally ventured out onto the freeway this morning. She rides surprisingly smooth out there! My dumb question is- What freeway speeds are yalls driving? I didn't want to push it past 50-ish but wondering if regular sustained driving in the 55-65mph range perfectly normal with these old machines or damaging to the motor?

Thanks and apologies for the long winded post!

Jeff

[Ggmac]

Rear gear ratio and tire size will determine the cruise speed.

[deuce_roadster]

What Ggmac said x2. 4.11s generally are too low for the freeway without an overdrive.

[GB SISSON]

To help answer this question can we get some input into what might be considered an acceptable sustained rpm? I have driven coast to coast with 4.11s many times with '60s and '70s pickups, but I tend to run 3/4 tons with a 32" tire. There are formulas that determine rpm @ 60 mph. They use base numbers representing tire diameter/circumference, 5280 feet, axle ratio etc. With a good flattie cruising RPM (stock engine) established the rest is just math. So, what do we want to run our V8s at for extended periods?

[cadillac512]

Personally, I like to stay under 3000 rpm on the highway. That rpm with a 4.11 rear gear and 29" tire will be 63 mph. Above that rpm it just feels too busy to be comfortable for my taste. My '41 Merc with 3.54 gear and 29" tire is just under 2600 rpm at 63 mph and really runs nicely there.

This isn't to say you can't spin 'em faster...but I prefer the above.


Terry

[ford38v8]

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A Ford flathead engine in as-built configuration will not redline under load. Valve spring float and ignition point float will limit the RPMs, and while the engine won’t sound happy at that speed, it won’t damage a healthy engine. Your ears will tell you a comfortable speed, until the red lights in your rear view mirror tell you otherwise.

[Kurt in NJ]

I drove the 39 with 60hp engine at 65-70 a lot, if it dropped to 40 on hills i went to 2nd gear.
In the stock model A i have driven the length of PA turnpike at 65
The 1-1/2 ton 46 truck had a 2 speed rear, usually kept that just under 60, it usually had about a 2 ton load of flea market merchandise, the guy that bought it drove it to california in 4 days, i suspect he drove over 60.

[deuce_roadster]

Don't know what the speed limit is where the OP lives but where I live it is mostly 60, 70 in some places. People drive 70-75+ here in WA. At 60 you get scarily tailgated and the finger.

[JayChicago]

Originally Posted by deuce_roadster

At 60 you get scarily tailgated and the finger.

Must be some nasty people where you live. I drive the Inrterstate in the right lane at 50-55 MPH, and the only finger I ever see is the thumb up. People generally love old cars, and people know old cars drive slower. Never saw any anger, only smiling faces as they pass.

[Ggmac]

Doen here in S Florida, doing 60 will get someone pulling in front of you and hitting the brakes . Braking is far more important to me on the highway than keeping up with traffic. I usually take the scenic ( slow ) route .

[Ford Freak]

The 3:92 rear axle ratio, as in my '52 F1, was a popular ratio in these trucks.
The "sweet spot" (where mine seems happy cruising) is around 50 mph. Thats ok by me!

[tubman]

As said above, it depends on tire size and rear end ratio. What I can add to the equation is that my '51 with a slightly modded '51 Merc engine with a set of Edmunds heads, a Rochester 2G, and a Mallory dual point cruises at a little over 70. This car has 3.55 gears and 225/75R15 tires. The engine is really happy at 2300 RPM, and starts to get unhappy at 2700 RPM.

Just plug that into your equation.

[SoCalCoupe]

Great thread. Really got me thinking. Haven't even driven my car out of the county since I bought it a year and a half ago. Essentially, the only way out is on a blue shield interstate with a 65 -70 mph average speed. In principle I'd like to do a long road trip.



I inadvertently found myself on I-5 following some friends a few months ago. 60 mph felt ok but it also felt like the comfortable top end both for the engine and suspension. Going faster than that doesn't feel right. Don't think there's anything wrong with the suspension, just that solid front axle feel like an old 4x4 pickup. Maybe the original shocks aren't doing so well; haven't checked them yet.



Got more interested and found a thread saying the rear end gears are stamped on the bottom rib of the banjo rear end. Found the 9 38 stamp which calculates to a 3.78 rear end. That works out to about 2700 rpm at 60+ mph. So, at 2700 rpm the engine sounds ok but more doesn't. Without an overdrive, I think I'll plan on <65mph.


Buying that overdrive or Columbia for 1-4 road trips over the rest of my life may not be very cost effective, but, who knows, maybe there will be more.

Originally Posted by tubman

The engine is really happy at 2300 RPM, and starts to get unhappy at 2700 RPM.

[bbrocksr]

[QUOTE=SoCalCoupe;2205726]Great thread. Really got me thinking. Haven't even driven my car out of the county since I bought it a year and a half ago. Essentially, the only way out is on a blue shield interstate with a 65 -70 mph average speed. In principle I'd like to do a long road trip.



I inadvertently found myself on I-5 following some friends a few months ago. 60 mph felt ok but it also felt like the comfortable top end both for the engine and suspension. Going faster than that doesn't feel right. Don't think there's anything wrong with the suspension, just that solid front axle feel like an old 4x4 pickup. Maybe the original shocks aren't doing so well; haven't checked them yet.



Got more interested and found a thread saying the rear end gears are stamped on the bottom rib of the banjo rear end. Found the 9 38 stamp which calculates to a 3.78 rear end. That works out to about 2700 rpm at 60+ mph. So, at 2700 rpm the engine sounds ok but more doesn't. Without an overdrive, I think I'll plan on <65mph.


Buying that overdrive or Columbia for 1-4 road trips over the rest of my life may not be very cost effective, but, who knows, maybe there will be more.



I[/QUOTE

9-38 is 4.22 9-34 is 3.78
Bill

[SoCalCoupe]

Originally Posted by bbrocksr

9-38 is 4.22 9-34 is 3.78
Bill

You're right. 9-34 is 3.78. The 8 got stuck in my brain. It's stamped 9-34.

[Bob C]

The Ford shop manual shows 4.27 or 3.92 ratios for the F1.

[Wiggles]

Thanks for the info everybody. I guess I need to see what my rear end gears I have and measure some tires. And maybe get a tachometer. Speaking of which what rpms do these motors like to spin at where do they not like to spin at?

Good stuff either way-

J

[TJ]

Originally Posted by Wiggles

Thanks for the info everybody. I guess I need to see what my rear end gears I have and measure some tires. And maybe get a tachometer. Speaking of which what rpms do these motors like to spin at where do they not like to spin at?

Good stuff either way-

J

Check the ID plate inside the glove box door. It will give you the rear end ratio as long as some prior owner has not changed the gears.

[52flthed]

I drive my 52 F1 all over, I've thought a lot about this, and honestly I just don't enjoy driving it on a large highway at those speeds. Sure it'll do 60-65, but is that really why I got the truck? Here in NJ, the southern part of the Garden State Parkway is doable for a few exits, as there is no heavy commercial traffic and its a pleasant looking well designed road. I couldn't imagine bringing it on a large 6 lane interstate like the I-95 or even a large 4 lane highway, you'd be holding everyone back. Even driving on some larger thoroughfares 6 lane roads with traffic lights, with large retail box stores, I just don't enjoy driving on them with the old truck. I stick to two lane country type roads which can get you anywhere you want to go. If you plan out your trip.

Don't forget it's not only the engine that you have to think about. It's the brakes, bias ply tires if you have them, and suspension, not to mention the steering wheel- windshield if you were in an accident god forbid. The steering wheel will crush your chest in an accident. Thats why they got rid of them as early as the fifties in cars, but trucks still had them.

[A bones]

Originally Posted by 52flthed

I drive my 52 F1 all over, I've thought a lot about this, and honestly I just don't enjoy driving it on a large highway at those speeds.

I stick to two lane country type roads which can get you anywhere you want to go. If you plan out your trip.
.

Might not be what Wiggles wanted to hear. BUT
Excellent point 52flthed,
When your truck was new those 4lanes were yet to be.
People still got around, as I do when I have my avatar buzzing.
So you give up a little TV time