How do you switch from a Standard Transmission to to an Automatic.

[dennishoddy]

The OP could buy a newer truck for the cost of a transmission swap. (Made sure I didn’t say tranny)

 

[2busy]

I did this exact thing to a 64 Impala but I had a doner vehicle. Didn't swap any rear end gears. That was early 80's.i took the straight 6 cyl and 3 on the tree out and put a small block 400 with auto transmission in

 

[swampratt]

Some people think cruising at lower RPM gets better MPG.
Not so all the time.. if the vehicle is not aerodynamic like a vette and is more like a sheet of plywood getting the RPM up while cruising will many times help MPG as you are not lugging it and you have less throttle opening if it is not being lugged.

My 1984 Ford van E150 got 2 MPG better with the 235-75-15 spare tire on the front bumper.
I kid you not.
Great bumper for hitting deer also.

Coolant temp plays a huge roll in MPH get it to 195 and MPG gets better than cruising around at 160 coolant temps.
I do not know if this is a Fuel injected deal or what but I like to lean out my carbs until they lean surge slightly on flat land cruising.

Then richen it up .001 at a time until it is gone then come up .001"-.002" in jet size and call it done.

Timing curves play a huge role in MPG..I like all my timing in by cruise rpm.
My 84 ford van weighed 6000 lbs and had 3.50 gear and I did not use Over drive.
Cruise was in the 2800 RPM area and .030 over 302 ford with ported everything and 2 barrel intake.

17.6 MPG this was Carbed and I recurved the distributor.
This was the MPG 95% of the time I filled it up.

I tried OD and it hurt MPG I tried more timing and it also Hurt the MPG.
It would either ping or lug and that is not the path to good MPG

 

[turkeyrun]

There are lots of things that CAN be done. That doesn't mean they SHOULD be done.



I had a '69 Datsun (Nissan now), 4 cyl, 4 on the floor, 4.38 rear end, whopping 57 HP.

'77 Buick donor car, built the V-6 to 275 HP, auto transmission, left the rear-end gear. Launch like a missile, but top end was around 75 - 80 mph.

 

[Bravo1413]

I did this exact thing to a 64 Impala but I had a doner vehicle. Didn't swap any rear end gears. That was early 80's.i took the straight 6 cyl and 3 on the tree out and put a small block 400 with auto transmission in

Different swap. 6 cyl. Would have lower gear ratio due to lower power. Putting in a v8 would have given you more power. He isn’t switching motors.

 

[2busy]

Different swap. 6 cyl. Would have lower gear ratio due to lower power. Putting in a v8 would have given you more power. He isn’t switching motors.

I did a transmission swap in a 58 Chevy pickup , pulled the granny 4 speed and put a 3 speed on the column. Didn't notice much difference except for low gear. That was my first vehicle I drove to high school.

 

[swampratt]

Sometimes output splines from the trans will be different.
There is a pilot bearing in the back of the crankshaft when using a standard shift transmission and it must be removed if switching to an automatic.
Flywheel needs to be replaced with a flexplate.
Coolant lines and cooler for automatic of course and possibly trans mounts. All easy stuff really.

Now sometimes the driveshaft will need to be a different length also.