87 GT VERT 3G and Heater Vacuum line help

techforlife · May 12, 2018

I just imnstalled a new 3G 130 amp alt and that turned out sweet,,looks stock,,I hid the wires well..but at start-up I get belt chirp..

The 3G alternator pulley is a lot larger,,so the belt is kinda short..i left the larger pulley on because I don`t think I need that really small pulley,,so did you guys encounter this,,put a longer belt on?????

I also only have defrost on my heater,,it`s an air conditioned car..i have a black vacuum hose dangling on the drivers floor,,lol

some could tell me where that goes would be sweet,,i`m getting too old to stand on my head searching under dashes anymore..lol

B

General karthief · May 12, 2018

Pics of belt setup.
Veryuseful.com has vacuum diagrams for the hvac, try looking behind the glove box door, if you squeeze the sides of the box inward a little it can flop down and dump all your crap in the glove box on the floor, not that they hold that much junk :shrug:

and you can get an eye on where that vac line goes.
i just noticed you wrote 'drivers floor', what is the size hose?

techforlife · May 12, 2018

IT`s about 3/16 around and black with a yellow stripe...I think it`s the nain line,,it leaks vacuum all the time..

B

techforlife · May 12, 2018

jrichker · May 12, 2018

b]The following are diagrams courtesy of Tmoss & Stang&2birds

Vacuum diagram 89-93 Mustangs

HVAC vacuum diagram

General karthief · May 12, 2018

Look for a small plastic manifold with a white vacuum line or it may connect directly to the back of the hvac dials, can't remember for sure.
I found it, there is a single hose from the back of the select dial with a connector that will plug into that hose.

techforlife · May 13, 2018

found it..the hose came off the switch assembly,which I knew,but couldn`t find the vacuum motor till I stood on my head and looked up for about 10 minutes,,lol

The hose went to the defrost motor,which I kinda new but couldn`t see..

Now if I can rid of the belt chirp I think I`m done for now..

Here`s some pics of the alternator install..

B

General karthief · May 13, 2018

Have you replaced the belt yet?
your adjuster looks to be within the wear guide.
is it charging good?

techforlife · May 13, 2018

going to replace the belt,,,but it did not chirp with the old alternator on it...I`m wondering if the belt is a touch short too though,,as the old alt had a real small pulley..

if it`s too short the belt won`t wrap arround the pulley as much as it should..lol

The belt isn`t cracked,,but likely 20 years old or better..everything else on the car is original,,plugs/wires/brake pads...everything...

the OE belt was in the trunk with the rest of the original parts..the guy kept everything..

Charges perfectly..

billison · May 16, 2018

I personally swap the stock fox alt pulley when I do the swap. On a fox set up the 3g pulley is a underdrieve

Boostedpimp · May 16, 2018

Your suppose to swap the stock pulley over to the 3g alternator. If you do that it'll solve your belt situation and probably get your charging back to where it should be during idle.

Blown88GT · May 19, 2018

billison said:
I personally swap the stock fox alt pulley when I do the swap. On a fox set up the 3g pulley is a underdrieve

Boostedpimp said:
Your suppose to swap the stock pulley over to the 3g alternator. If you do that it'll solve your belt situation and probably get your charging back to where it should be during idle.

Pulley is too large.

techforlife · May 19, 2018

Cool......thanks guys,,i`ll swap the pulley tonight..I was going to try it yesterday but I blew a header gasket...previous owner put the wrong gaskets on it as they were large port gaskets and barely touched the head ports..lol

B

techforlife · May 20, 2018

So....this is getting interesting...lol

I swapped the original pulley onto the 3G and now the tensioner bpttoms out?????

new 91 inch belt on her ,,the length that the car came with...and the tensioner bottoms out and belt squeels like hell at start-up..

So... the new 3G looks to havemounting bolts straight across so the centerline is unchanged?????

the OE pulley on the alternator appears to be 1.9 inch across the tips of the belt grooves..

The pulley that came with the 3G puts the belt wear indicator closer to 1/2 way..

So..does anyone know where I can get pulley measurements to identify what was played with???

I`m beginning to think they put an overdrive alternator pulley on this years ago since these were known for low charging at idle..

any help is appreciated..it may actually be fine with the 3G pulley on it now though..lol

Boostedpimp · May 21, 2018

Are you running any underdrive pulleys?

I've used a 1.89" pulley before on one of my cars and it's for sure a overdriven pulley. It did work great for the car I put it on but that car had a tiny crank pulley with underdrive water pump pulley and had the typical charging issues at idle with the 3g alt. Your case may not call for such a small alt pulley though.

Mustang5L5 · May 21, 2018

To find the proper pulley size, you need to do a a little bith of math.

As a rule, you want to try to stay under 16,000 max RPM with the typical 3G 130A alt, but you want as small of a pulley size as you can possible fit on there to allow for good charge at idle RPM.

What size is your crank pulley? Try and roughly measure where the belt rides, not the lip that holds the pulley on. If it's a stock crank pulley, it's roughly 6".

So with OE alt pulley of roughly 2" it's a 3:1 ratio. At 5500 RPM redline, your alt would spin at 16,500 RPM. If you plan on cruising around and rarely going above, say, 4500-5000 RPM, you can probably go with a smaller pulley and be fine.

I think mine is a 1 7/8" alt pulley (1.875) but i'm using it with a 4" underdrive crank pulley. The 1.875" pulley with the stock crank pulley would be a 3.2:1 ratio meaning 5500 RPM is now 17,600 RPM on the alt..which might be creeping into danger territory on the stock bearings. Basically with that pulley 5000 RPM would be max safe engine RPM for the alt and anything above it would briefly put you in danger territory. However, your idle charge would be fantastic, so it's one of those decisions you need to make based on actual use of the car. A stock AOD convertible cruising around with easy AOD shifts at 4500RPM would probably be fine. A dedicated road race car spending much of it's life at high RPM near redline might want to consider a larger diameter alt pulley. Does that all makes sense.

techforlife · May 21, 2018

Boostedpimp said:
Are you running any underdrive pulleys?

I've used a 1.89" pulley before on one of my cars and it's for sure a overdriven pulley. It did work great for the car I put it on but that car had a tiny crank pulley with underdrive water pump pulley and had the typical charging issues at idle with the 3g alt. Your case may not call for such a small alt pulley though.

I`ve got to check the crank pulley,,but all the other pulleys have ford part numbers on them so....probably not,,unless Ford made underdrive pulleys???

B

Blown88GT · May 21, 2018

techforlife said:
...

I swapped the original pulley onto the 3G and now the tensioner bpttoms out?????

new 91 inch belt on her ,,the length that the car came with...and the tensioner bottoms out and belt squeels like hell at start-up..

So... the new 3G looks to havemounting bolts straight across so the centerline is unchanged?????

the OE pulley on the alternator appears to be 1.9 inch across the tips of the belt grooves..

The pulley that came with the 3G puts the belt wear indicator closer to 1/2 way..

So..does anyone know where I can get pulley measurements to identify what was played with???

I`m beginning to think they put an overdrive alternator pulley on this years ago since these were known for low charging at idle..

...

Does " tensioner bpttoms out" mean too tight or too loose?
"new 91 inch belt on her ,,the length that the car came with" - this means nothing, you use whatever length gets between mix & max on
tensioner.

Overdrive pulley:
https://www.summitracing.com/parts/asp-520004

techforlife · May 21, 2018

too loose....it applies no tension,,or very little..

So it has an overdrive alternator pulley,,,that link shows 1.9 inch as overdrive,,that`s what was on it...

So I have a noise, sounds like belt noise at start-up...I`ll remove the belt tomorrow and verify if the noise goes away...the pulley the 3g came with puts the tensioner at midway which is good...but I did not have this chirp noise before the alternator install...and kit`s pissing me off...lol

B

techforlife · May 21, 2018

Mustang5L5 said:
To find the proper pulley size, you need to do a a little bith of math.

As a rule, you want to try to stay under 16,000 max RPM with the typical 3G 130A alt, but you want as small of a pulley size as you can possible fit on there to allow for good charge at idle RPM.

What size is your crank pulley? Try and roughly measure where the belt rides, not the lip that holds the pulley on. If it's a stock crank pulley, it's roughly 6".

So with OE alt pulley of roughly 2" it's a 3:1 ratio. At 5500 RPM redline, your alt would spin at 16,500 RPM. If you plan on cruising around and rarely going above, say, 4500-5000 RPM, you can probably go with a smaller pulley and be fine.

I think mine is a 1 7/8" alt pulley (1.875) but i'm using it with a 4" underdrive crank pulley. The 1.875" pulley with the stock crank pulley would be a 3.2:1 ratio meaning 5500 RPM is now 17,600 RPM on the alt..which might be creeping into danger territory on the stock bearings. Basically with that pulley 5000 RPM would be max safe engine RPM for the alt and anything above it would briefly put you in danger territory. However, your idle charge would be fantastic, so it's one of those decisions you need to make based on actual use of the car. A stock AOD convertible cruising around with easy AOD shifts at 4500RPM would probably be fine. A dedicated road race car spending much of it's life at high RPM near redline might want to consider a larger diameter alt pulley. Does that all makes sense.

I`ll check the crank pulleY diameter tomorrow too,,thanks..

B

87 GT VERT 3G and Heater Vacuum line help

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