I just installed a tac on our 1988 motorhome which is powered by a 460 engine. My question is how many times should this transmission shift and what RPM's at 55 mph would you expect the engine to be running at.

 

Shift points are controlled on a C6 trans using engine speed, vehicle speed, manifold vacuum, and governor pressure within the trans.
An E4OD uses some electronics to control shift points using the same info as above by way of shift solenoids.
A lot depends on how fast the vehicle is going, load, and engine speed.
If you know which trans your vehicle contains some approx shift points could be suggested.

 

How do I Identify what Auto transmission I have. Is it stamped on the tranmission where I can see it. Its a 25 ft Holida Rambler Class A motorhome. Does 3500 Rpm at 55 mph sound right. I believe it shifts twice after you start moving. I've been trying to find the operating RPM for this veihicle but I never thought anything would be so difficult.

 

If it is still either on the driver's side door or door pillar should be a trans code for that vehicle. 3500 sounds a little high for 55 MPH.
If the shift lever has an OD lite on the **** it is most likely an E4OD.

 

This motor home does not have the normal ford cab. Class A motor homes may use a ford frame and motor but the body is made by the company so there are no factory doors pillars. There is no OD light which I assume means Over Drive, the selector is on the dash and it has D-1, D-2 and D. I've only us the D while driving. The last time we drove it we heard a very loud noise coming from the engine compartment and after shutting it down and inspection, we started it back up and the noise was gone. I had the fan which has a clutch on it inspected and was told it is ok, but I thought the engine was running at a higher RPM than in the past, as I cannot find any info on what rpm it is suppose to run it make me nervous.

 

Since there is no OD it is possibly a C6.
It should shift thru 3 gears and around 40 MPH the converter should lock up.
What you can try to confirm this is; On a level and straight road, steady throttle
Start out in D1 , that should keep the trans locked in 1st, then depress D2 and you should see the engine speed slow down as it is allowed to shift into 2nd gear. Take it up to around 30-35 MPH and depress the D button which should allow it to go into 3rd gear.You should also notice another drop in engine RPM as the shift is made.
Once you get over approx 45 MPH you should feel the converter lock up.
Let us know what you found.

 

I'll give it the test tomorrow, went to the granddaughter Volley Ball Game.

 

Well I finally got around to doing what you said on starting in D-1 up to 3000 Rpm and then into D-2 then at 40 mph shifted into Drive. It shifted each time and the Rpm dropped each time. I still cannot find a plate on the body that states what transmission I have but it is a 1988, V-8 460, that I do know. Knowing that it is shifting when I manually change the transmission selector gives me some relief. I still would like to know what RPM's these devils run in Drive. Like I said I had the Tach added, before that I just drove it. You speak of the Converter, what does it do? Question I know may sound silly but your talking to an ole fart that is still trying to learn. lol

 

A lot of torque is required to get the vehicle moving , that is where the torque converter comes in. You have high RPM and high torque. Once moving hi torque is less required and if the engine RPM is reduced as in shifting there is a mileage benefit. At approx 35-45 MPH the clutch in the torque converter locks up since less torque multiplication is required, and there is less lost RPM motion . Cruising speed like 60MPH usually is maintained around 2100 RPM Could be more or less depending on rear axle ratio. If you have a hi ratio rear differential it will require more RPM to attain a particular speed.