STREET MACHInES, Engines, gearing and etc

[Ol' Ron]

Been a number of post, about rear end gearing, over drives and performance mods to the engine. There are a number of things you should consider before you make a decision, This may help.
Application of the vehicle. Groceries getter, open road travel. Etc.

For this you have to consider the performance of the engine. A bone stock 239 engine in good tune puts out aprox 80 hp at 3000 rpm. Torque runs from a max of 150 at 2k to 133 at 3k . Actually alittle less with generator and fan.

All this information is available in JWL's book "Flathead Facts"
The original Vehicle took most of this information into consideration when built.

For "street use" the only way you can improve this is to increase the torque output of the engine in the operating range. 2 to 3000 rpm and the only way you can do this is by compression and displacement.

Dual exhaust, more carbs and a hot ignition, doesn't get it done, just milling the heads does more in this range. I hope more people take part in this thread, this way we'll all learn allot and maybe save a few buck in the process.

[Pete]

For street engines, both Ron and John have excellent books that cover anything you need to know.

[JSeery]

Originally Posted by Ol' Ron

Been a number of post, about rear end gearing, over drives and performance mods to the engine. There are a number of things you should consider before you make a decision, This may help.
Application of the vehicle. Groceries getter, open road travel. Etc.

For this you have to consider the performance of the engine. A bone stock 239 engine in good tune puts out aprox 80 hp at 3000 rpm. Torque runs from a max of 150 at 2k to 133 at 3k . Actually alittle less with generator and fan.

All this information is available in JWL's book "Flathead Facts"
The original Vehicle took most of this information into consideration when built.

For "street use" the only way you can improve this is to increase the torque output of the engine in the operating range. 2 to 3000 rpm and the only way you can do this is by compression and displacement.

Dual exhaust, more carbs and a hot ignition, doesn't get it done, just milling the heads does more in this range. I hope more people take part in this thread, this way we'll all learn allot and maybe save a few buck in the process.

Good post Rod. And like Pete posted, lots of good information in their books.

[V8COOPMAN]

Originally Posted by Ol' Ron

Torque runs from a max of 150 at 2k to 133 at 3k.

Possibly a LITTLE off topic here, but this is a better reason to consider a 5-speed trans (4gears + O/D) such as a T5 for it's ability to keep the engine operating within the favorable torque band (RPM-wise), vs the importance of the benefits realized from the O/D. When you think it thru, the T5 gives you the best of BOTH worlds. Just a thought for the few folks that are actually considering the use of one of these transmissions. You know what they say....."Once you go T5, you'll never go back", or words to that effect! DD

[Pete]

Originally Posted by V8COOPMAN

Possibly a LITTLE off topic here, but this is a better reason to consider a 5-speed trans (4gears + O/D) such as a T5 for it's ability to keep the engine operating within the favorable torque band (RPM-wise), vs the importance of the benefits realized from the O/D. When you think it thru, the T5 gives you the best of BOTH worlds. Just a thought for the few folks that are actually considering the use of one of these transmissions. You know what they say....."Once you go T5, you'll never go back", or words to that effect! DD

X2 on all of that.
I have converted several and every one has said it is the most fun you can have with your clothes on.

[tubman]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by Pete

X2 on all of that.
I have converted several and every one has said it is the most fun you can have with your clothes on.

These are obviously older gentlemen.

[Ol' Ron]

Yes, I sometime think it was made for the flathead. As well as the RTS 3 spd with OD

[Pete]

Originally Posted by Ol' Ron

Yes, I sometime think it was made for the flathead. As well as the RTS 3 spd with OD

Forget that RTS3 thing. It has absolutely horrible ratios for either performance or gas mileage driving. Mainly, it is short one gear.

[JSeery]

Pete, when are you going to publish a book? I'd be interested!!

[Pete]

Originally Posted by JSeery

Pete, when are you going to publish a book? I'd be interested!!

LOL....You can't imagine how many times I have had that question.
I have to reply, when would I do it? I am running on 32 hour days now and enjoying every minute of it.
One of the big reasons is, my experience is in circle track and Bonneville racing and interest in that is very small compared to street racing and I use the term "street racing" because when you get right down to it, that is what all of the economy diddling with flathead Ford engines is about.
If you want to go get groceries or go to show and shines you don't need a dry sump oiling system etc etc. You just want to beat the 55 GMC pickup next to you at the light.
All of the data that can possibly be published about somewhat modified flatheads has been published many times.
I know most of the people that are interested in all out flatheads and any new ones can easily find me. My computer is on 24/7 and I spend at least an hour a day answering vintage race email. That is the way I want it.
So, no book for the foreseeable future.

Thanks for thinking about it anyway.

[Terranova]

So if I already have a merc crank and EAB heads I should be ok and switching from a single carb to a duel intake will just be icing on the cake, right?

[Ol' Ron]

Pete, I have an RST in my 47 PU behind a "stock"280 ci engine. 2GC carb abd converted Chevy distributor. 3.73 44A rear. Living in Vermont, it's perfect match. I saved the T-5 for the roadster, have to watch my pennies.

[V8COOPMAN]

Originally Posted by Ol' Ron

Living in Vermont, it's perfect match. I saved the T-5 for the roadster, have to watch my pennies.

Ron.....Do you know WHICH T5 you have? There are so many variations with the gear ratios, many of which have a ridiculously low 4.03 1st gear, along with pretty wide spacing between gears. Ideally, it's a close-ratio gear set with the 2.95 1st gear to keep the revs tightly-grouped in the relatively-narrow torque band on that flatty. Generally, if the input shaft has 26-splines, it's gonna be the close ratio set. Remember, any T5 case can be re-fitted with any of the different gear sets (gear ratios). But the gear sets must be swapped as a complete set....no way to individually tailor ONE PARTICULAR gear's ratio....complete gear sets only. DD

[flatjack9]

Originally Posted by V8COOPMAN

Ron.....Do you know WHICH T5 you have? There are so many variations with the gear ratios, many of which have a ridiculously low 4.03 1st gear, along with pretty wide spacing between gears. Ideally, it's a close-ratio gear set with the 2.95 1st gear to keep the revs tightly-grouped in the relatively-narrow torque band on that flatty. Generally, if the input shaft has 26-splines, it's gonna be the close ratio set. Remember, any T5 case can be re-fitted with any of the different gear sets (gear ratios). But the gear sets must be swapped as a complete set....no way to individually tailor ONE PARTICULAR gear's ratio....complete gear sets only. DD

A properly modified and tuned flathead will have a very flat torque curve from 2000 rpm to 3500 rpm.

[V8COOPMAN]

Originally Posted by flatjack9

A properly modified and tuned flathead will have a very flat torque curve from 2000 rpm to 3500 rpm.

Hey Flatjack….Every combination of parts used and mods employed will obviously produce optimum torque ranges that will vary to some degree, BUT I UNDERSTAND YOUR POINT. The point I was trying to make is that you want to keep your RPMs (while rowing thru the gears) comfortably within the limits of whatever your particular torque range may be, without dropping the RPMs below the lower limit when you shift to the next higher gear. Using YOUR torque figures, and when utilizing a 3-speed trans, it might be a possibility that you could shift from 1st gear to 2nd gear at 3,400 RPMs. It's also entirely possible that when making the shift that the RPMs may drop to somewhere below 2,000, whereas utilizing the extra gear that a 4-speed offers would obviously make your RPM drop LESS, to a more-desirable RPM well-above your lower limit. Virtually all 3-speeds have too much of a spread between gears for optimum torque utilization.....where acceleration rate is a factor. Go drive somebody's car with a Muncie 4-speed or a T5 and the difference becomes remarkably obvious. DD

[Gene1949]

Originally Posted by V8COOPMAN;

Go drive somebody's car with a Muncie 4-speed or a T5 and the difference becomes remarkably obvious.

Well spoken, for sheer drivability a 4 speed or a 5 speed were made for the flathead. I put a T-10 and a Granada [Ford] automatic rear in 25 years ago, long before many had thought about the conversion. The T-10 and Granada are basically "bolt-ins".
Once I drove it never once thought about reinstalling the OD.
The auto gear makes for a very comfortable [2600rpms] 70MPH car. The drop-in center section makes for an easy gear change if desired.

[flatjack9]

I've got the RTS in my 39 with a 3.70 rear axle. Really like it.

[Ol' Ron]

One way to save money is to have your cast iron heads angled milled .050" with the majority of the material removed from the valve side of the head. Then check for piston to head clearance. A Dremel can fix any interfere. adds a point in compression

[Darrell S]

I need an education. What is an RTS3 transmission?

[frnkeore]

They are good, strong transmissions, with aluminum cases! Maybe not the best for a hot rod but, they would do well in a PU, especially with a 255 ci or larger engine, with stock or mild cam.

They are also know as a Top Shift Over Drive.

They come in different gear sets, for different engines.

Frank