I have a 1981 F150 with a 302 and automatic trans and have been going through hell to get it running correct. It use to run with a really high idle and stall when put in gear so i rebuilt the carb and it starts right up. It still seems to idle high but runs kind of smooth. I unplugged the distributor vaccuum hoses and checked the timing and it said it was about 10 degrees of so i adjusted it to 8 btc. It now runs with a much lower idle speed. I can shift into drive or reverse and it doesnt seem to make any difference with the way it runs (maybe it isnt going into gear) but when i try to go back to park it make a high pitched grinding noise and is hard to get into park. It shifts good when its not running. I am not sure if i have the carb or timing ajusted correctly, would this make a difference? where should i start looking to return it to operating condition. Thanks in advance.

 

This behavior with the shifting the lever, is this new or is this a result of something you changed?

BTW please fill out the rest of your profile so we can see where you live, click User CP in top-left corner to do it, thanks.

 

I think it must be something i did. I rebuilt the carburator, fixed a vacuum leak and tried to set the timing. It used to shift into and out of gear back before the carb was rebuilt but it would generally stall after put in gear. Now it starts and runs but after you put it in gear, it grinds when you try to put it in park. I did also fix the ignition switch on top of the steering column.

 

I don't know anything about an automatic transmission but I know some have got a kickdown rod that downshifts the transmission upon flooring of the accelerator, and some overdrive transmissions have got I guess a similar rod or cable that, when mis-adjusted, causes the death of the transmission in short order.

Hopefully others who know more will stop by....

 

I haven't touched the kickdown rod. I just wasn't sure if there was a way that the transmission syncronized with the engine and if it had anything to do with timimng and carb idle speed? I will post anything i find out. I forgot, I also replaced the starter. Is it possible that i have the wrong starter and it is grinding on the starter gears when i try to put it in park? I have no idea what transmission is in it? I read that the C4 has 11 bolts around the pan, mine has many more. It is a canadian truck with a K in the vin for transmission? Thanks

 

K is a C6, that's what it came with out of the factory, you can see if somebody has changed it on you:



I believe there is also a device called a Vacuum Modulator which makes the transmission aware of the engine's operating status at any given time but I know anything other than it exists. This will *definitely* be sensitive to engine idle speed and ignition timing as both of those attributes can drastically affect engine vacuum.

I can't see the starter motor being involved...... well, wait........

To actuate the starter motor, all that happens is that power gets applied to a small terminal on the starter solenoid via a red/blue-stripe wire, #5 in this picture from Franklin2:



In normal operation, when the key tumbler is turned to START, it actuates the ignition switch on the column behind the dash which then supplies power to the correct circuits; with an automatic transmission, the START circuit also includes a Neutral Safety Switch, it needs to be closed to allow power to be transferred.

That's normal operation; if your particular truck has had its wiring hacked to all Hell and something mechanical happens to apply electricity to the wire feeding #5 as you move the lever to Park, well, I guess *that* could get the starter motor involved.

I am also confused by the following:

So, are you saying that you can move the lever from Park to Drive and you're not sure if the transmission is doing the right thing and in fact allowing you to drive the truck forward (or reverse as the case may be)?

And then putting the lever back into Park creates this grinding noise?

Can you test and see if the transmission is, in fact, allowing you to move forwards or backwards or not?

 

Does the truck move when you put it in gear? The only way I can think of for a C6 to make a grinding sound when trying to put it into park, would be if the driveshaft was turning. Park is nothing more than engaging a locking lever into the output shaft of the trans.
If the rearend is having issues, or the rear wheel are off the ground, this would allow the driveshaft to turn as if the vehicle was moving. This would be the way to make a grinding noise while shifting into park.
Of course, if the truck is a 4wd, the same would occer if the transfer case was in nuetral.

 

The truck is 4 wheel drive. It is a C6 transmission. I havent been able to get it to restart today. I started it right up and adjusted the idle mixture screws and choke thing and moved the distributor a little and now it wont start. When i get it started i ill see if it moves. Is it possible that the new starter isnt correct for the transmission? Is it true most 81 F150's have a C4 transmission? Maybe NAPA gave me a starter for a C4.

 

Almost there. It no longer grinds going back into park.I had the 4X4 shifted into N? Thanks for the help.