STICKY: 3G Interchange Facts. Read if you're thinking 3G

[Chaseman]

Not sure if this has already been said but just so it's written down in this thread. A 8.25 spacing 3G from a 3.8L Taurus will not fit a 75 FE 390 with a upper alternator mount , I've tried. The 7" Alternator from a 3.0L Taurus fit pretty good until I realized I needed to clock it different. Ended up having to grind the back of alternator a touch. Also instead of adding a washer I changed my mind and bought a new pulley from summit racing which fit like a glove and isn't a worn out pulley. So far one V-Belt is holding steady. Good news is I can probably use the 8.25 alternator on my 66 mustang on the 289.

Oh and I mention the 75 390 cause my truck is a 71 body on a 4x4 75 frame and running gear.

I found the only pic I had of the alternator , I'll take a better one later. And the only decent pic of the truck i could find is a still from a video.

[basketcase0302]

Chaseman » Tue Mar 07, 2017 11:36 pm
Not sure if this has already been said but just so it's written down in this thread. A 8.25 spacing 3G from a 3.8L Taurus will not fit a 75 FE 390 with a upper alternator mount , I've tried. The 7" Alternator from a 3.0L Taurus fits perfect though with no modifying except adding a washer behind the pulley. Good news is I can probably use the 8.25 alternator on my 66 mustang on the 289.
Oh and I mention the 75 390 cause my truck is a 71 body on a 4x4 75 frame and running gear.

Wanna' see the 4 X 4!

[MadJoe]

Jeff,

Is your DRW really running a 302? I'm very interested in hearing more. Right now I have original 360, and I plan to put a 4BBL on it (I have a perfectly cleaned and rtr 4bbl intake off a 390 that was in a '63 Galaxie 500, just need to source a good carburetor or budget the Holley Sniper EFI retrofit - leaning towards the later). Figure if all else is good that should be enough (PO put some nice dual exhaust on it, but still OEM exhaust manifolds). But a 302 crate engine, in the event all goes "kaboom", would be more budget-friendly than a lot of alternatives, so could be my backup plan if you're saying it's enough.

-Joe

[basketcase0302]

by MadJoe » Sat Mar 25, 2017 1:14 pm
Jeff,
Is your DRW really running a 302? I'm very interested in hearing more. Right now I have original 360, and I plan to put a 4BBL on it (I have a perfectly cleaned and rtr 4bbl intake off a 390 that was in a '63 Galaxie 500, just need to source a good carburetor or budget the Holley Sniper EFI retrofit - leaning towards the later). Figure if all else is good that should be enough (PO put some nice dual exhaust on it, but still OEM exhaust manifolds). But a 302 crate engine, in the event all goes "kaboom", would be more budget-friendly than a lot of alternatives, so could be my backup plan if you're saying it's enough.
-Joe

Joe, Sadly I sold the truck to a guy named Todd who lives in NY, (I don't think he comes on the site)? Yes the 302 pushed the truck just fine at .030 over with flat top pistons and an RV cam in it with a 2BBL. Your reasoning is exactly why I did it-for the economics of it as well as the 17 mpg I got with the dually. How'd you do the body swap and not wind up with the space between the cab and bed that most guys here wind up with.
Love the truck!

[Lone Ranger]

Hey guys I'm thinking of doing the swap but reading through this and on other sites I feel I'm only getting bits and pieces from many different sources. Does anyone have a step by step like approach for dummies? I have a 69 highboy with a straight six 300. The motor is not stock but I'm guessing it's 1970s motor. My alternator now has 7 inches between mounting points.
Also does this swap do away with the voltage regulator? I'd also like to run all new wire while I'm at it- so what would be the recommended gauge for all this for best performance? Thanks in advance

[Lee]

Lessons learned.

I performed the 3G upgrade to my 1970 Highboy about 500 miles ago.

Performed GREAT,.... until yesterday when I heard/felt a bearing growl and started getting fan belt slip "whine".

Long story short: I read/watched everything I could before conversion. I then bought an alternator at Salvage Yard and also bought a re-built kit online. Installed rebuild kit. I noted that some folks stated that a shim needed to be installed behind the 2 groove V-belt pulley for clearance issues. When I installed the pulley I did not encounter any clearance issues so no shim was required.

Big mistake.

What I failed to notice was the amount of End-play in the shaft of the Alternator. I would bet there was a 1/16" amount of play. End result was the rear bearing failed after only 500 miles. When I tore down the alternator I noticed wear on the face of the alternator from the pulley.

Replaced both bearings and installed a shim behind the pulley. Time will tell if this is the fix.

Hope this helps,

[Lone Ranger]

I also didn't put a shim in cause everything fit fine. Guess I better check it all out again. 3G swap was easy just like everyone says. Had to grind the back of the alternator and also the bracket some but it was no sweat.

Put my digital mega fuse on the firewall. As you can see... it works while idling.

I used this diagram and hooked the green wire to my trucks green wire with the red stripe coming off the voltage regulator. Ran it awhile like this to make sure it worked then chopped everything out I didn't need and cleaned it up.

[WhitsEnd]

.
READ THIS IF YOU HAVE BELT SQUEAL AFTER A 3G UPGRADE

A dual V-belt or serpentine conversion is usually recommended.

Even the smallest 3G puts a big demand on a single V-belt. If you run a single belt, you need to have close to half the circumference of the pulley for engagement. Less than this, and it's likely to squeal, at least on startup. So, if you are running the alternator with a single belt and it also is driving the water pump, you won't have sufficient wrap.

Most that drive the alternator with a single belt exclusive and directly from the crank, don't have any issues. This scenario allows more wrap, or belt contact on the alternator pulley.

In my scenario, I had multiple accessories and only had a single V-belt available to drive the alternator and it also had to drive the water pump. Therefore, I didn't have enough belt engagement and the belt squealed during startup. I added an idler pulley to change the exit angle from the alternator pulley. I happen to also be using an A/C mounting bracket made and sold by a forum member, so that's where I mounted the idler.
Here's a link from my build http://www.fordification.com/forum/view ... 85#p748634

[Zorm]

Picked up a 3G from the Summit parts bin a few years ago, supposed to out put 150amps and finally got around to installing it. I had to grind down some of the lower mounting point. I also had an old dealer added A/C so did not have a good upper curved alt adjustable mounting point. Ended up hitting a local junk yard, grabbed all the old style metal curved and grooved alt mounting bars I could find. Ended up using one from a 80's Dodge 4x4 with a 318.

So then been reading these posts and I have the wiring like on page 3, reflectionpoint's post. I am going to wire up like him, do I need to look for a resistor wire from the factory regulator to get the alt to charge? do I need to use the 560ohm resistor? Also will be adding a volt meter to the F600 dash any existing stock wiring I can use or just run new. Just a minor note I will have all my grounds going to one point, a grounding bar. Will be adding a duel fan set up from a Ford Windstar to.

thanks for thoughts