I am having problems with the charging system on my 1972 F100. The truck has a 302 CI engine and AOD transmission from a 1982 Crown Vic and a serpentine belt system from an 89 E350. This whole scenario started from getting 9 mpg. I attempted to rebuild a couple of carburetors after discovering the carb on the engine had the large throttle plates. After several attempts at rebuilding a couple of electric choke carbs without any success I gave up and installed a manual choke 2100 and repaired a couple of vacuum leaks, this smoothed the engine out. Now the charging system problem developed. I have changed the alternator, same issue. I changed the 1972 original voltage regulator with a like one from China. Things worked for about 10 miles. The alternator from the 89 E350 is high amperage regulator, will this work with the original style regulator? I am on my way this morning to get another alternator since the new one just got sounds like a cat fight right after installation. this has been discussed in another thread and pictures of the alternator were requested, I am going to try and attach them, last attempt locked up my computer and I had to switch.
Here is a link to previous discussions; https://www.ford-trucks.com/forums/1...f-ideas-2.html

 

What Amp Alternator are you using ? I can see it is a big case 1G alternator but what amperage..

 

Wouldn't it be a lot easier swapping in a 3G alternator? Then you can get rid of that contact point type regulator.

 

The alternator is a 100 Amp

 

I really appreciate all of the help and information received from everyone. I have solved the problem, at least temporarily. It appears I was the victim of a once in 20 lifetimes issue. It appears the voltage regulator, alternator, battery, and ignition control module all took a dump about the same time. This all started in trying to fix a fuel problem. I am continuing to pursue getting the mileage from 9 mpg to above 20 where I think it should be for the setup I have. I am trying to retain the 2100 2150 carburetor and not having a lot of luck in rebuilding them.

 

From 9 MPG to 20 that is a lot to ask for.
I don't think it is all about the carb, what is the rest of the drive train like?
Rear gear and tire size, is the 302 stock or built up, is the AOD going into OD?
Good luck
Dave ----

 

I will give a history of the changes made. When I bought the truck it was getting +/- 20 MPG.

Here are the changes I made:

Installed a serpentine belt system for an 89 E350.
Changed the rear suspension to flex-o-matic.
Had the AOD rebuilt by a qualified professional.
Advanced the timing from very late to 12 deg BTC.
Installed new plugs and wires
Rebuilt a couple of carburetors, both large and small throttle plates. ( this caused a lot if other problems) Currently have a manual choke 2100 installed from a 352 that was getting 13 mpg.
Tire size unchanged.
Rear end unchanged.
Moved the gas tank from behind the seat to a mid-ship style.
The engine is a 302 1982 date.
The transmission is a Ford AOD, 1982. The transmission shifts fine throughout the 4 gears.
It does have an after market cable downshift installed, not much fun to adjust!

If there is a leak I have not been able to locate it, have layed under the truck for 30 minutes with it running.
I did hook up the emissions canister.

Any and all suggestions, directions, or advice will be greatly appreciated.

 

What have you done to accommodate the TV rod for the AOD with the 352 Carb.

 

Installed a Lokar cable system.

 

So when and what was done to make it drop to what you are getting now?
Something you did has to stand out why it dropped.

I am getting about 14 MPG with my 81 F100 flare side: 300 six (stock other than EFI manifolds), T18, 2.75 rear gear, 235 / 75 / 15 tires and that is combo of 65 MPH high way to work (30 miles) and 45 MPH back roads back home. I hope to install an over drive unit to see what that will do.
Heck I only get 15 MPG in my 02 Durango w/360 efi auto OD and 3.92 rear gear best I ever got was 17 MPG on the high way with no AC doing 65 MPH.
Dave ----

 

That I would like to see a pic of it on the carb... I bet the ratio is out and this is some of the problem...

 

The only way you're going to get 20 mpg is down hill with the engine off. My '99 Explorer 302 gets 17 @ 70mph and you're pushing a lot more air and weight.

 

Hay lauxg, I think the inquiry from the previous poster was more along the lines of what are the actual gear ratio numbers you have, and what actual tire size you're running.
And how are you figuring fuel economy? Are you saying your truck with it's old engine got 20mpg? Or your truck and this swapped-in engine got 20mpg previously? Or is it that this engine in it's original Crown-Vic home in a passenger car was getting 20mpg?

Paul

 

Good news! Congrats.

Nah, more like once in only three lifetimes. That kind of crap happens all the time with these old trucks!

Well that aughta' teach 'ya!
You're supposed to just let it go and hope it fixes itself. Otherwise you're susceptible to "sympathetic failures" from all systems.

Good luck on that. Pretty sure there ain't a member here (or likely a person left alive!) that can get that kind of mileage from a V8 with carburetor in a full size truck. I hate to lay absolutes on anything, but it feels like that just ain't gonna' happen.
Never a '72 existed that got 20mpg with an old V8. And any extra efficiency that the '89 Crown Vic engine had was with it's fuel and spark management system. And even then they only got 20mg on a good day with all the planets aligned, taking full advantage of aerodynamics and rolling resistance. My friend's '98 Towncar with 4.6 Mod motor is lucky to get 15.
But then, that's not really sitting at a steady 60mph with the cruise set on a flat highway. If your mileage is based on what the car got originally, what is that based on? Advertised economy ratings? Previous owner claims? Your experience (was it your car?) and testing?

Just wondering how you arrived at the 20mpg expectation in an older truck. For example my finely tuned and well geared '79 has never gotten better than 13.5mpg. Normally it's 12 max and that's highway only and maintaining 55mph.
Not the same truck or engine I realize, and my '68 Bronco actually does get 20mpg, but that's with a fully equipped Explorer engine, in a lighter truck, maintaining 55-60mph with cruise set. I think I can get better with taller gears in the diff, and am going to test that theory soon. But I question your ability to get that in a pickup truck with a carburetor and small V8.

But hey, good luck! I'd love to see it, then document every aspect of your setup so others can benefit too. Including me!

Paul