I am waiting on my refund to come in going to buy all the stuff to do my 3G conversion so I can do it when I drop my new motor in.

Problem is I know there is a 7" and a 8.25" center to center sizes for the 3G. Gary`s website indicates these V belt trucks should use the 8.25" center to center but I took an alternator off a customers '82 F150 with a 302 that had a 7" center to center.

Does that sound right? I haven't checked my alternator on my truck as I don't want to go pulling anything apart yet till I am ready to do my engine swap.

I looked on here on the 3G posts and all I could find is just that the 3.0 V6`s used the 7" and the 3.8 V6`s used the 8.25", not a single mention of what should be the proper center to center alternator for a 302 powered truck. Sure hate to order a 7" center to center and find out I should have got the 8.25".

Another question I have I didn't see mentioned, it talks about flattening out the lower pivot bracket to get it to fit behind the alternator ear as it is a wider ear than the old 1G. Looking at the 3G alternators I see a casting line in the ear that appears to me that could be used as a guide to cut the ear down eliminating the need for modifying the lower bracket to get it to fit. has anyone on here tried to do it this way vs modifying the original bracket? In my eyes seems easier to use a hacksaw and saw off a chunk of the aluminum ear to make it fit the oem bracket vs trying to flatten out the oem steel bracket.

 

I can't help on the size but this ear you talk of is on the ALT. Right?
Part of the problem with a modified ALT. is if you break down on the road you can't just get an ALT. from anywhere with out needing to cut the ear off.
Just my thinking.
Dave - - - -

 

Correct it is on the alternator the ear I'm talking about.

Problem is still going to be there if I break down on the road due to alternator if I modify the bracket a 3g alternator will have a serpentine belt and wont be a direct bolt on as I'd have to take the 3g apart.

 

Your truck could have come with 2 size alternators. The smaller 60amp (7") will ave all the wires connected on the back. The larger 70amp (8.25") will have a T shapes plug in the side. You can put your 2 groove pulley on the 3G but don't use the fan. The fans are internal on the 3G.

 

Thanks for the reply. I take it they are backward compatble?

I'm thinking of going with the large case 3g as it's not much more money.

 

This will entail some rewiring be aware of that.

Really there is no need for a 3G in these trucks unless you are running a high draw stereo system or elec cooling fans. The 1G is just as reliable provided you keep your connections at the regulator clean..

 

I agree with matthewq4b on the alternators, My 1981 still has the original alternator

and it does fine. I have a stock radio with upgraded speakers and run an MSG 6A

ignition and it works fine. No issues with how it charges.

 

Well this truck has a am/FM cassette stereo OEM style as well as dealer ac. Blower speed on ac slows down at idle as well as headlights dimming slightly.

I have a headlight relay kit powering to her silver star ultra bulbs in hella eco composite housings.

I also have two 100w kg driving lights bolted on my front grill guard.

I also have a galaxy cb radio with a small amp and center load Wilson 2000 antenna.

My future goals will be addition of four more lights on a bed mounted roll bar but I'm still not 100% on that just yet.

I figured for the dimming headlights and slowing blower I should upgrade to correct that issue as well as future proof the truck on mods.

Also be easier to mount the alternator and make changes while on the engine stand.