Want o go highway speeds ??? Need opinions.

[Dan 1939]

My 1939 pickup overheats if I go over 60 MPH.
Do I change the rear gear to 3.25:1 ratio or, install a T5 transmission from a Chevy S10 with overdrive to be able to travel at highway speeds.
Which is the better plan and makes most since financially.
Thanks for your thoughts and guidance.

[Charlie Stephens]

Why does your truck overheat, is it really due to the rear end ratio? What is your current rear end ratio?

Charlie Stephens

[drolston]

Pushing that truck through the air at 60 mph takes a certain amount of horsepower, regardless of what rpm the rear end dictates for that speed. The amount of heat generated by the engine at a given horsepower will vary a little with the rpm at which that horsepower is being delivered, based on the engine efficiency at a particular rpm. With the 4.11 gears normal for that truck, you are probably well over 3,000 rpm. With 3.25 gears the rpm will be down to maybe 2,500. The fan will be drawing less horsepower and the engine may be a bit more efficient at that rpm, but I doubt it will cure overheating.

Let's rule our a few things:
1) Water hoses not swollen or crimped
2) Take out the thermostats and try it. Maybe one or both are not opening properly.
3) Does your truck overheat sitting at idle, on a hot day? If so, check for retarded timing
4) Have you checked the water pumps; vanes intact and in good shape
5) Exhaust not restricted; crimped pipe or choked muffler?
6) After a hard run, check spark plugs to too-lean condition (white powder versus toast color)

[1931 flamingo]

I'd start with the radiator....................JMO FWIW At 60mph the fan shouldn't come into "play", does it overheat if left at idling for any length of time??


Paul in CT

[39pu]

Ignore the overheat concern what is most cost effective way to drop rpms at hwy speeds?

[Kurt in NJ]

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The 39 with a 60 had no problems going highway speeds of 65-70, it had 4.44 rear, ran cool flat out

My model A --stock 3.78 rear has traveled the whole length of the PA turnpike on 95 degree day at 65, didn't overheat

Start with the radiator, it's not the rear ratio

[Phil Gillespie]

Originally Posted by 39pu

Ignore the overheat concern what is most cost effective way to drop rpms at hwy speeds?

Larger diameter tyres.
Phil NZ

[B-O-B]

Double check your timing. advance it a bit.

[Charlie Stephens]

Originally Posted by 39pu

Ignore the overheat concern what is most cost effective way to drop rpms at hwy speeds?

What ratio is your current rear end? Are you sure your speedometer is correct?

Charlie Stephens

[fortyfords]

Do a Mitchel overdrive.

[Juergen]

With stock tires and a 3.78 rear end, the Service Bulletins say at 60 you will be at about 2750 rpm which is a little high for prolonged flathead use. So a 3.54 will get you at about 3.54 / (3.78) x 2750 = 2575 rpm while a 3.25 gets you at about 2360 rpm. Finding a used 3.54 will probably be easier and cheaper than buying a new 3.25 and getting it set up. A bigger tire may be the cheapest. A 6.00 x 16 tire has a diameter of 28-29 inches. So one equivalent to a 3.25 (13% change) would need a diameter of about 32 inches. Of course use a turtle for a 3.25 (17 tooth I think)

[philipswanson]

Most economical method, stay under 60. You will pick up increased fuel mileage too. 60 is fine for the highway.

[JSeery]

One of the problems I have seen with higher sustained speed in the 30s cars/trucks is fatigue cracking in the fenders.

[woodiewagon46]

Do you have a fan shroud and all the sheetmetal that directs the air thru the radiator? I would do all that others have suggested before I do what you want to do.

[JSeery]

If your really determined to drive at higher speeds, I would go with the over-dive. That is the approach I took.

[Pete]

All of the above are good suggestions but the root of the problem is the engine and/or cooling system. After that I would check the headlights, horn and steering wheel.

[petehoovie]

Are you sure you want to drive on the highway? > https://www.youtube.com/watch?v=m_b_Pb6Ynjs

[3twinridges]

Originally Posted by petehoovie

Are you sure you want to drive on the highway? > https://www.youtube.com/watch?v=m_b_Pb6Ynjs

LOL, good one!

JB

[Tinker]

If you are on the 101 in LA you are either doing 100mph or creeping at 5mph.


Block might need a flush also, pull heads and dig out with a coathanger/long screwdriver/or both, to get sand out.


Lower rpms with power at any speed is a good thing. OD isn'e a bad idea. Running 7.00 tires, 3:78 rear, and a mitchell 36% od, cruise 70. Bit much at 36% OD, but my engine can pull it so far.


Mitchells aren't cheap, but no frame cut or open driveline conversions. Both take time and money. Put the mitchell in a day and still have my original torque tube and didn't need to do anything else.



Maybe a wash as far as money, I don't know. Don't know if it's better either. I like it.


Let us know what ya did. good luck.

[OHV DeLuxe]

I had a 48 running hot all the time, rebuilt and advanced the ign 2 degrees, still hot,
then i ran 50/50 white vinegar and water for one day around the backroads, in the afternoon bottom tap was clugged all of a sudden, so i had to pull the bottom hoses of.
they were full of grit and crap from the entire cooling system, about 4 full hands of this stuff piled up in the pan, even what looked like casting sand. Flushed two times.
it stopped overflowing, it ran too cool all of sudden, and had a much more even heat distribution and dispatch.
The cheapest fix ever, about 5 Dollars. I`ve done the same on many cars with fascinating resaults every time. Try it

[fortyfords]

In my opinion, my 40 was designed to run 60 mph all day long according to the owners manual and it didn't overheat. But I always felt like it needed one more gear, it would run 70 but there was just so much more engine noise. I had 3:78 rear but determined that the car was made for old roads and was not comfortable on freeways; also with no a/c the windows had to be open and that's noise also from everyone else going 80 mph. So if you want to run freeways and go fast, build a street rod with a/c and have your old stocker for all the fun trips around town and plain just having fun. Those street rods will spoil you rotten when going fast.

[expavr]

Overheating and traveling at highway speeds are two different issues. I think the responses regarding overheating have covered that question. Regarding traveling at faster highway speeds, I'm running a set of 4.11 gears, a 49 Merc O/D trans, and 30" tires. The Tonner can cruise all day at 60-65 MPH in O/D with the engine turning 2000-2200 RPM and no heating issue. Keeping up with traffic if that's a concern can be accomplished in many ways - the use of an O/D trans or similar unit being one. If operating at higher speeds is important, the more important question that should be considered is how fast the early Ford brakes and your reflexes will respond in an emergency while operating at that speed. Its one thing to be driving at 65 MPH in direct drive and another to be driving at 65 MPH in O/D. I can attest to the fact that the effect engine compression has on braking is noticeable especially in a panic braking emergency.

[JHFORD51]

Temps aside the hands down easiest way to run same speed at lower rpm is increasing tire diameter. Moving away from the 28" dia 6.00x16 to a bigger tire, even all the way up to a 32" dia 7.50x16 or radial equivalent (if you dare) can make a big change in how hard the engine is working. One has to be cautious to not venture too big in the rear and get too much rake because the rear end gear oil will migrate through the torque tube. So make sure what you select doesn't look goofy for your taste and won't scrub the front end when you turn. Short of tires, the 3.54 gears or a mitchell/Columbia are other bolt ins. T5 plus install kit plus new driveshaft plus open drive conversion plus x member modification plus something to control fore/aft rear axle movement is a good deal of effort and expense. You still have to stop it so keep the brakes in mind. The factory Lockheed brakes not designed for today's cell phone equipped drives that like to dart in front of you and stop suddenly...

[Tinker]

I guess I assume most understand going faster means stopping faster.


Brakes before power or speed for urban driving.




.

[AnthonyG]

As many have said your over heating isn't the fault of your RPM at high speeds, u've either got cooling system issues or clogged up water jacket veins in the engine. Having said that, I did what Tinker and JKFORD51 suggested on lowering rpm, bigger rear tires. I went with the modern equivalent of 750 16's 33"dia. replacing the stock 600 16's 28"dia. & reduced rpm by 15% & speedometer reads 15% slower than actual now. Can run at 60 with comfortable engine RPM (Motor not screaming) could easily go faster but won't with mechanical brakes. As Tinker said unless U have dam good brakes and i'll say updated suspension u probably don't wanna go much over 60.

[Flathead Fever]

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The first thing I ask people is, "did it work at one time setup the way it is now"? Has anything been changed from how it left the factory? Do other people have identical vehicles that are not having the same problem as you? If their flatheads are running cool and yours is not, it nots because its a flathead as most people will want to tell you. Its not because it needs a new $700.00 aluminum radiator. You need to find out what has gone bad on your vehicle?

Before we do any serious damage diagnosing it, make sure you have a 50/50 mix of antifreeze to keep the coolant from turning to steam. If you get it hot enough on a road-test to create steam you are going to crack your block. Steam is something like 1600 times the volume of water. 1600 times as water will not fit into your engine, it will try and it will break your block. Do not let an engine get hot enough to make steam unless its powering a vintage train.

Make sure your base timing is set correctly, the advance is working and not stuck and if it has one, check that the vacuum brake is working. This probably has nothing to do with it but timing can make an engine run hotter so make sure it is working correctly.

When you first assess an overheating problem you need to decide if the problem is in the section that created the heat or the section that takes it away? I start with the section that gets rid of the heat. The first thing you should do is check the coolant level. Is it loosing coolant? Where did this coolant go, did it go out the radiator overflow, out a leaking radiator, bad radiator cap, leaking from a hose, is it leaking inside the engine,down the outside of the engine, is a water pump leaking? No obvious sign of leaks, good! Before you fill it up see if you can see the tops of the tubes down in there, see if they plugged full of stuff. The early Fords have that baffle in the top tank between the built in overflow tank and the radiator tubes. You are probably not going to be able to see much down in there same with a GM style crossflow radiator. If you could get an inspection camera down in there you might be able to see the tubes. I don't have one so I've never tried it. Its one of my next tools I'm buying. If you can see junk stuck in the tubes you have probably found your problem.

Another thing you can do is feel the radiator's core preferably on the frontside where there is no fan to take your handoff. If you have an infrared temp gun instead of your hand that would be even better. Do this when you first start the engine, when its cold. If you don't have thermostats in there compare the temperature in the hoses, top tank of the radiator, and the upper part of the radiator core, they should feel like they are warming up at the same rate. If you have thermostats you will need to wait until they open. Sometimes you can feel sections of the core where the tubes are plugged, there will be little or no heat in these spots. Once after everything has been at operating temperature for a while its not as easy to tell if the you have cold spots in the radiator.

Coolant flows from the engine into the top of the radiator. So the larger chunks of rust get stuck in the tops of the tubes. The entire tubes can get plugged solid. You can try back flushing the radiator by flowing water in through the lower radiator hoses and out the top. Stick a garden hose in the bottom with a rag stuffed in there to make a seal and turn it on. Just remember that radiator is only rated for 4 lb.'s of pressure so don't get too carried away. Make sure you have the cap off. The reverse flow "might" unstick some stuff stuck in the tops of the tubes. It really helps if you can remove the radiator and flip it upside down. You'll also get an idea of how easy the water can flow through the radiator without backing up. It probably will not cleanout tubes that are completely plugged. If you still feel like its not flowing good then it needs to have the tubes cleaned out by a radiator shop. It might even need a new core. You need to flush the block out really good while you have the radiator disconnected, or you'll just plug your clean radiator right back up again.

At 60 mph there is more than enough air flowing through the radiator to carry the heat away from the cooling tubes. You could remove the fan and it wouldn't make one bit of difference at that speed. Before you go on a test drive you could also check to make sure you don't have bent radiator fins on either the front or back side and that they are not plugged up with dirt. The air has to be able to contact the metal fins. If the fins are covered in dirt that insulates them from transferring the heat to the air. If you travel on dirt roads the fins need to be gently spray off, don't bend them. It doesn't take many bent fins to block off 10% or more of the air flow.

At work, I found that nine-times out of ten, if the engine would run cool at idle or low speeds but overheat as the load increased the problem was a plugged radiator. Just a couple miles from the shop was an exceptionally steep hill about a mile long that required the gas pedal to by buried to the floor on a truck. With a bad radiator I could watch the temp gauge climb as I went up the hill, as soon as soon I crested the hill the temp gauge came right back down. That was the main test I used to diagnose a plugged radiator.

If you had a head gasket problem, a crack in block, bad thermostat it would "most likely" overheat at any speed. That's not a rule set in stone but "most" of the time I found that to be true.

I did get my butt kicked one time. I had a F-600 overheating climbing that hill. I thought, It has to be a radiator. So I pulled the radiator, which takes two people to lift out of there. I sent it out and had a new core put in it and it still overheated? Then I tried new thermostats, nope? One time durig 30-year's, I saw the impeller come loose inside a water pump. So I tried a new water pump, nope? One time I had a radiator shop use so much solder they plugged the tubes up. This one looked okay in there. It was not the engine. I took it to a different radiator shop with an old-timer in it. He looked right in there and said, "here's your problem, someone installed a core with tubes that are too small". That fixed it and became my new radiator repair shop. So you also need to make sure the correct radiator core is there with correct number of rows of tubes, the correct size of the tubes and the correct number and design of the fins.


You would be really disappointed if you installed 3.25:1 gears. You'd trade away your acceleration for a lower rpm at 60 mph. It might even overheat worse on a grade with 3.25 gears than 3.78s. If the engine was under a load and trying to pull those higher 3.25 gears, you would need to step on the gas further and under a load more fuel and air would equal create more heat in the cylinder. I'm willing to bet that your vehicle cooled just fine at one time with your current gear's and tire sizes at 60 mph.

The low horsepower of a flathead needs those 3.78.1 gears to help it accelerate. Those gears multiply the amount of torque of your engine by 3.78. With 3.25 gears you will be loosing 14% of that torque. You also need to remember how much larger the diameter of Early Ford tires are compared to say a 1965 Mustang. Most of those early Mustangs had 3.25 gears with a manual trans. They can get away with those high gears because of the small diameter tires. The base model 289 V8 also had almost 2 1/2 times the horsepower of your flathead to pull those gears. You need those 3.78s, especially if your getting a load of lumber, drywall or gravel.

[Flathead Fever]

It posted it twice so I deleted the second one.

[coolcoupe]

Hi Flathead Fever, My 47 stock engine/rearend overheats when I go any speed over 55 mph or idles for a few minutes. Any ideas what the cause is ? There about 13000 miles on the engine and has done this since I bought this car. I've been running it with no stats and 50/50 mixture of coolant.The dizzy was done by Mr Linder so should be fine. Moe

[FortyNiner]

Originally Posted by coolcoupe

Hi Flathead Fever, My 47 stock engine/rearend overheats when I go any speed over 55 mph or idles for a few minutes. Any ideas what the cause is ? There about 13000 miles on the engine and has done this since I bought this car. I've been running it with no stats and 50/50 mixture of coolant.The dizzy was done by Mr Linder so should be fine. Moe

Have you flushed the cooling system?

[coolcoupe]

Hi, thanks for the reply, no, I have not but will have to wait for spring as my little garage has no heat. I had given it a quick flush but will have to do a better job in a warmer month. I was hoping for a few ideas of things that I must of missed. Any other things to check ? Moe

[38bill]

Dan 1939, does your pickup actually overheat and boil over or does it just run at a higher temp at hwy speed?

[Flathead Fever]

Originally Posted by coolcoupe

Hi, thanks for the reply, no, I have not but will have to wait for spring as my little garage has no heat. I had given it a quick flush but will have to do a better job in a warmer month. I was hoping for a few ideas of things that I must of missed. Any other things to check ? Moe

If you don't backflush the radiator, run water through it in the opposite direction of the normal flow. That is to flush it in through the bottom and out the top it won't push that stuff out that is stuck in the tops of those tubes. Most likely it won't help at all but its something you can try for free. That stuff is usually so packed down in those tubes that a radiator shop will need to remove the top tank and run a rod down inside each tube to unplug them. They might not be able to save the tubes and the entire core of the radiator will need to be replaced. Its not cheap to re-core a radiator. Its not much cheaper than buying a new one. If you want to keep the vehicle as close to original as you can then you re-core the original radiator


This is a good video. Watch this youtube video of a radiator with plugged tubes.

https://www.youtube.com/watch?v=sUeGbvHfGUA

At lower speeds there are still enough tubes flowing to take away the heat. At higher speeds that engine is under a heavier load, there is more air and fuel burning and its going to create more heat. It needs every tube that radiator has to carry that heat down the tubes where it can be absorbed by the fins.

Is this your problem, there is know way to say for sure. All kinds of things can go wrong. If the problem has been gradually getting worse. Most of the time its the radiator getting more and more plugged up.

You don't see plugged radiators as much as you use to on the newer cars. The tanks are plastic with a rubber gasket making the seal to the core. The seals leak between the tanks and the cores before they usually get old enough to get plugged up. They are just throw away radiators. Some people try to fix them but its best to just buy a new one.

[Old Redneck]

My buddy has a 40 ford son. and had 4:11 gears. I talk him in putting 3:25 and what a difference. At 60 the engine is still quiet not screaming. My 35 pickup has 3:54 and at 60 the engine is dreaming. I don't like that. I have seen two cars with 3:25 and what a dream. We live in the mountains and no problem.

[Ol' Ron]

Back in the day we ran 5.86 gears with 32 Inch tires. Speed on the back streight away approached 85 MPH. considering the gearing the engine RPN was qround 5k. Crank driven fans were not allowed, For radiators from Chrysler products that AC which were 4 core. Feacher races were 20/25 laps, At the end of the race oue water temp was 210/220 and the oil 230/240. We took a few cool down laps, but that did't help much. At preset I like running my engines 180/200. Seem to last longer run better get great mileage.

[JSeery]

Originally Posted by Ol' Ron

Back in the day we ran 5.86 gears with 32 Inch tires. Speed on the back streight away approached 85 MPH. considering the gearing the engine RPN was qround 5k. Crank driven fans were not allowed, For radiators from Chrysler products that AC which were 4 core. Feacher races were 20/25 laps, At the end of the race oue water temp was 210/220 and the oil 230/240. We took a few cool down laps, but that did't help much. At preset I like running my engines 180/200. Seem to last longer run better get great mileage.

Ron, I always have to chuckle a little at these semi stock engines "screaming" at highway speeds. Don't think many are accustom to non-overdrive transmissions and lower rear axle gearing. These cars/trucks came out of the factory with these gears and ran fine at higher speeds. To me 2500 to 3000 rpm is not that big a deal.

[Tinker]

At 5g's for a rebuild. How long you screaming at 3000 on rpms.

I'm a stocker, but run a mitchell just because it bolts in and lowers my rpms on a new rebuild. No harm no fowl, also give me two gears in reverse, hahaha

I'm beting on torque over highspeed rpms.

Thinking ... back 30's-40s people didn't travel more then 50mph on a road that was less then great for more then a bit. Wasn't till the hwy projects of the 50s that OD even came out on factory production. Maybe a coincidence.

[JSeery]

Tinker, that's not how the folks I have know drove!

[Tinker]

i don't know js, I'm sure guys were doing 1200 mile trips at 60 mph the whole trip in the 30s. NY to LA.


But maybe some Families were doing 300 mile trips in the 40s at 60 all day long. I don't know...


In 1920 most people never lived or traveled more then 12 miles from where they were born. If they did it was a venture.

Not that it was the Oregon trail or anything.

[40cpe]

Originally Posted by Tinker

Wasn't till the hwy projects of the 50s that OD even came out on factory production. Maybe a coincidence.

Overdrive was in factory production cars in the '30s and '40s on several make cars, notably Studebaker, Lincoln, and Packard. Ford first offered it in '49 when they went to open drive line.

[Phil Gillespie]

Here in NZ open road speed is 100 km/hr max. So 55 to 60 mph car runs good and stays up with traffic flow. We're just a small country.
Phil NZ

[Tinker]

Originally Posted by 40cpe

Overdrive was in factory production cars in the '30s and '40s on several make cars, notably Studebaker, Lincoln, and Packard. Ford first offered it in '49 when they went to open drive line.

I had a FORD 53 with a I6 215 three speed with overdrive. Could do 70mph all day long.


My point being long distance travel at high speeds. Roads just weren't the same as today. Maybe in the twenties and thirties people were cruising along at 60mph all the time. Route 66 was constructed in 1926.


Maybe for a vacation or moved. Not daily.


All concidered.... Just from a standpoint of simple bearing wear, gas consumption, and wear and tear. Less rpms is not a bad thing.

[Ol' Ron]

The New OHV Ford six was one of the best engines Ford ever made. Much better than the Flathead V8 it replaced.

[Tinker]

I love the flathead foremost and forever as an engine.

For overall usage for the average guy I agree. That I6 is a great motor. Very underrated. Good power and gas mileage. Coined the "mileage maker" by ford.

The 53 I6 215 was first year, the next year the 223 came out (lot of changes and not very interchangeable). Up till the 60s the 223 was a workhorse, also with a 262 version in trucks. Pretty much a cheap I6 that just ran and ran. Sold off my last nos barker highlift rockers arms to a guy here doing a build. Later truck "56ish", 223, slant6 distributor, and with dual 1904 glass bowl Holleys.


Yblocks had torque, but they were a heavy beast. Great motor though. Lot's of power.

[Ol' Ron]

I had a 52 Ford PU and couldn't believe how strong it was. Ir was an old farm truck, but a tuen up brought it back to life and was a work horse for me. I sold it to a buddy of mine and we restored tit with a 302 running gear. Don't remember what happened to the engine.

[Flathead Fever]

I went on a rpm calculator. Driving 60 mph, with 6.00X16 tires (28.56" diameter) and 3.78 gears your rpm would be 2669. With 3.25 gears the rpm would be 2295. Your only talking about a 374 rpm difference. For the difference in rpms I'd rather have the better acceleration for driving around town. You also need to consider the added weight of the emergency spare parts you need to carry incase your old Ford quits. Water pumps, generator, entire ignition system, maybe a radiator, gallons of fluid, tire tubes, tire pump, tire spoons, your entire tool box, a floor jack, creeper,awn chair and a barbecue while you wait for the tow truck. You might just want to go with the 4.11s.

Nobody is correct, It depends on what kind of roads you will be driving on the most. Were all use to these overdrive transmission with low rpms cruising down the freeway. Screaming engines use to be normal but then so was rebuilding them every 50k miles.

To give you a comparison. A 1965 289 2V Mustang with a manual 3-speed trans left the factory with 6.95X14 tires (25.3" diameter) and 2.80 gears. That's 2231 rpm at 60 mph.

Here are some before and after photos of the offramp to my town. I just happened to take these yesterday to compare to an old postcard I bought.. That was old highway 99. The main highway heading out of CA towards Arizona. That was probably the rush hour Photographed during the early 1930s? Its now the 10 freeway and that's what it look like almost all of the time that the sun is out. Five lanes of bumper to bumper traffic and where I Live this considered a small country town. That's what the freeway looks like for 75 miles. No need for 3.25 gears here. I would need the 3.78s and a knee replacement for the hundreds of times I would start out from a stop.

[AnthonyG]

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Dan 1939 ??? did u figure it out?

[Marv]

Originally Posted by Ol' Ron

I had a 52 Ford PU and couldn't believe how strong it was. Ir was an old farm truck, but a tuen up brought it back to life and was a work horse for me. I sold it to a buddy of mine and we restored tit with a 302 running gear. Don't remember what happened to the engine.

The only flathead Ford that I ever owned that did not overheat or cracked block was a 47 coupe with the flathead 6. It was not great for gas mileage but it would out run most stock V8s.

[RalphG]

As good as the 223 six might be there is no way I would trade my Merc flathead 8 for it. The smooth rumble of the V8 is a sound I'll never forget. The six just sounds boring. I rode a 59 Ford school bus with the 223 six. Tough and reliable old engine but a little under powered in that truck chassis. And of course no V8 sound.

[Tinker]

Ralph I did say "good" power... not "great" power. Very reliable.

The 1953 OHV I6 215 (not to be confused with the earlier 6, which as great) Put out as much HP as the 53 flathead. Same as the first 239 yblock 8 in 54.

Flat8 is the greatest sounding motor flat motor.

Think this guy was trying to put a rod through his block for this video.
https://www.youtube.com/watch?v=r9ua24Ue4wM






.

[Tinker]

Originally Posted by Flathead Fever

I went on a rpm calculator. Driving 60 mph, with 6.00X16 tires (28.56" diameter) and 3.78 gears your rpm would be 2669. With 3.25 gears the rpm would be 2295. Your only talking about a 374 rpm difference. For the difference in rpms I'd rather have the better acceleration for driving around town.

Another reason I like the Mitchell OD. Splits every gear. Keep the 3.78 and split the gears at the box. Basically a 6sp with OD. Options are 28% or 36% i believe. I run a 36% od in my truck.

Mitchell Box is synco, so shift in 3rd up/or down. Same in first. Lot's of guys using them from model As to early fords. So they have a rep of being a good unit. Bolt in, doesn't destroy anything. NOTE: Some issues with floor fit on 35-36 cars I believe, requiring some floor mods. But Trucks, your good to go.


There is a volvo od too and a f150 box options with the torque tube. Require a bit of machining and research.




Dan did we scare ya away?





.

[mfirth]

The I block 6 with a 4 / 2 split manifold sounds GR8. I had one & some guys thought it sounded like a 348 C----y. Maybe that ain't so good........?

[Supertuner700]

How much are the mitchell overdrives? Will they fit a 1938 model 85 1.5 ton?

Originally Posted by Tinker

If you are on the 101 in LA you are either doing 100mph or creeping at 5mph.


Block might need a flush also, pull heads and dig out with a coathanger/long screwdriver/or both, to get sand out.


Lower rpms with power at any speed is a good thing. OD isn'e a bad idea. Running 7.00 tires, 3:78 rear, and a mitchell 36% od, cruise 70. Bit much at 36% OD, but my engine can pull it so far.


Mitchells aren't cheap, but no frame cut or open driveline conversions. Both take time and money. Put the mitchell in a day and still have my original torque tube and didn't need to do anything else.



Maybe a wash as far as money, I don't know. Don't know if it's better either. I like it.


Let us know what ya did. good luck.

[corvette8n]

Originally Posted by Tinker

I guess I assume most understand going faster means stopping faster.

Brakes before power or speed for urban driving.

.

The factory Lockheed brakes not designed for today's cell phone equipped drives that like to dart in front of you and stop suddenly...

Get your overheating problem fixed then worry about stopping next, then go fast.

[V8COOPMAN]

Originally Posted by Supertuner700

How much are the mitchell overdrives? Will they fit a 1938 model 85 1.5 ton?

Supertuner ....This thread is over two years old, but since you asked, the Mitchell OD "kits" seem to start around ~$3,200 bucks. But the REAR END in the 1.5 ton truck that you mention is a totally different animal than the 'CAR' and 'light pick-up' truck rear ends that the Mitchells are normally installed in. I'm not sure the Mitchell is adaptable to what you have. Why don't ya give the Mitchell folks a shout for some worthwhile answers? DD

[Supertuner700]

Thank you

[sunshine]

I have a stock 39 pkp. How are you going to stop this thing going 70 you didn’t say what you are going to do for brakes ????

[JayChicago]

When I first got my car I fantasized about an overdrive to keep up with traffic on the interstates. But then I read a post from Kube that changed my mind. He said something like this:
“I can imagine driving our cars at 70, but I can’t imagine being able to safely stop or steer from that speed”

Now I happily drive the right lane at 50-55, waving back at people smiling at the car as they pass.

[TomT/Williamsburg]

I think we can all agree that driving our cars is all about the journey and not the destination so much. So, taking the road less travelled is something I do a lot. But, there are times when an interstate can’t be avoided. When that happens, I use it during the time of least amount of traffic. You can’t always do that and my avatar has been a road warrior for many years.

The rpm calculator is your best “arm chair” way of figuring out your most desired and best combination of tires, rear gear, final tranny gear output, and the speed you want to run on an interstate if the need arises. Larger rear tires will reduce your rpm but perhaps impede acceleration, same thing with your rear gear. Only you can decide what your best combo is for your type of driving, how much you want to keep your car all stock, and your pocketbook.

For example, my avatar was meant to go across country. So, at 75 mph I wanted the engine to turn 2500 rpm. 235/85-r16 tires (nearly 32” tall), 3:54 rears, 5-speed with 5th gear having a .86 ratio, accomplished that. But I built the car from scratch to do that. For an already nicely finished car, especially a stocker, those are a lot of changes and the car will not be the same. I also dug out a 1 gallon bucket of sand from the motor - that cut down on overheating tremendously imho.

For anyone I would play with tire sizes until I found a combo that would work well enough at Highway speeds for an hour or two, 65-70, and still kept the look of your vehicle. If you still overheat, and flatheads like to run between 22-2800 rpm because they need heat to function right, you need to address those issues that are causing you to do so.

One last thought - my max speed in my avatar is 85 mph (Texas has 85 mph speed limits) at 2800 rpm because I carry 400 lbs plus of extra parts in my trunk all the time. I hit a head wind and I lose 3mph. The engine does not know mph as it is just as happy at 22, 25, or 2800 rpm.


You are not driving a daily driver but an 70-80+ year old car - drive it to enjoy it, take those back roads and enjoy the journey with friends, family. If you want to go 75, build it to do it - for others, just slightly and reasonably modifying a stock vehicle, if you do desire, can do some if not all of what you desire - just enjoy it.

[V8COOPMAN]

Originally Posted by TomT/Williamsburg

You are not driving a daily driver but an 70-80+ year old car - drive it to enjoy it, take those back roads and enjoy the journey with friends, family. If you want to go 75, build it to do it - for others, just slightly and reasonably modifying a stock vehicle, if you do desire, can do some if not all of what you desire - just enjoy it.

Lots of pretty damn good info and suggestions in what TomT has to say above, especially if you're wanting to add an overdrive trans of some sort. Do your homework, and do it thoroughly, especially when it comes to understanding GEAR RATIOS and how they can help....or HURT you, and my emphasis is on the ratios of ALL of the gears in your trans. We keep hearing of too many folks trying to use a complete S-10 T5 transmission (because the shifter location is farther forward).....when all they REALLY should have done was substitute the S-10 REAR HOUSING for that STOCK rear housing on their much-more-friendly-geared Camaro (2.95 1st gear) or Mustang (3.35 1st gear) trans. That street-friendly 2.95 is far-more friendly and useful than that 4.03 1st gear in an S-10 T5. It's just TOO easy to assemble a 'custom' T5 with the gearing and shifter location that fits your entire envelope. DD

[Teacher John]

Originally Posted by Tinker

I love the flathead foremost and forever as an engine.

For overall usage for the average guy I agree. That I6 is a great motor. Very underrated. Good power and gas mileage. Coined the "mileage maker" by ford.

The 53 I6 215 was first year, the next year the 223 came out (lot of changes and not very interchangeable). Up till the 60s the 223 was a workhorse, also with a 262 version in trucks. Pretty much a cheap I6 that just ran and ran. Sold off my last nos barker highlift rockers arms to a guy here doing a build. Later truck "56ish", 223, slant6 distributor, and with dual 1904 glass bowl Holleys.


Yblocks had torque, but they were a heavy beast. Great motor though. Lot's of power.

I have a '64 F250 with a hopped-up 262. She runs like a raped ape. I changed the rear gears from 4:88 to 4:10 and installed a Detroit Locker. She'll burn those 7.50 16's. The original radiator took a huge dump, so I installed a 3 core AL radiator. She runs cool all day long in the Texas heat.