mitchell tansmission

[JayJay]

A B carb, and Brumfield head reduces the RPM a measurable amount?

Assuming you have not changed the transmission or rear end, or added an overdrive, changing the carburetor or the head does not change rpm at a given ground speed. Having these mods might should make it so you get there faster...

What they will do is increase the torque and horsepower at that rpm because the engine is breathing better and able to put more fuel/air mixture through.

 

[Bruce of MN]

Don’t forget the rear end ratio as well. Most common for cars 3.78 and originally trucks were 4.11 (there are exceptions to most everything) I have yet to encounter a truck that still has the 4.11’s in it but I’m sure that there are a lot of them out there. I personally have no sat down with a calculator to sort out the details but I have been told that with an OD the 4.11 rear works well.

A Mitchell with a 3.78 gives you 3:1 overall, which seems pretty good to me, especially in a hilly area.

 

[Synchro909]

A Mitchell with a 3.78 gives you 3:1 overall, which seems pretty good to me, especially in a hilly area.

My Phaeton has a 3.78 ratio differential and 5.25X21 tyres which increase the overall wheel diameter by 5% and with the 26% Mitchell overdrive, I end up with an effective drive ratio of 2.86. It handles hills pretty well but on the flat, open roads, it comes into its own. It is just ticking over at 85kph and doing it easy at 100 which is the legal limit on most country roads here. Best economy comes at about 85kph. 25-6 miles per imperial gallon or 21.3 per US gallon. I haven't found a hill yet that will stop it.

 

[nkaminar]

"So what is corrected HP?" Gene F, Post #19

The atmospheric pressure varies depending on the altitude and weather factors. The atmospheric temperature also varies. In order to compare horsepower and torque, the readings are corrected to a standard pressure and temperature.

I forget the details. It has been 60 years since I studied this in college.