My 40 Dodge Truck Build - Maybe a 41 LOL

vacuum the system and draw it in? Then you are also sure you wont have leaks.

If the fan motor is a 120 watt or bigger, it'll be fine, if it's an 80 watt, it's likely not gonna pull enough air.

It is a 120 watter OI....good looking out

So I'm messing with aligning my pulleys. I had to put a shim between my water pump flange and water pump pulley to eliminate the backside of the pulley rubbing on the water pump housing.

I took .200 off the backside of the crank pulley to line it up with the water pump pulley. I couldn't move the water pump pulley out because I'm very close to the electric fan.

I have to machine back the length of the alternator bushing and mill back the other alternator lug to align that pulley to the rest. The alternator bracket has a slot for tightening the belt. All good.....not sure. I'm worried that I don't have enough belt to crank pulley contact. Please take a look at the picture and let me know what you guys think.

Another option is to leave the alternator as is which is out front and I can stack a second crank pulley and run to belts. The alternator bracket will tighten that belt but I'll have to build some bracketry for an idler for the second belt.... crank to water pump.

What do you guys think would be best and is anyone running an idler on the driver side of the motor? If so would you have a picture?

Lastly....not sure if it matters but looking at the front of the motor....what is the rotation of the crank pulley.

Thanks guys!

I'm not sure which way the crank rotates but by looking at the blades, the alternator is made to rotate clockwise as you look at it from the front and that is the rotational direction of almost every engine I've ever known of. Except some older Honda 4 bangers.

Maybe something like this....I might be able to make it adjustable or maybe the alt slot which would be the same bolt would be enough?

I think the belt to pulley contact you had w/o the idler was fine.

offroadrolls said:

I think the belt to pulley contact you had w/o the idler was fine.

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Thanks ORR..... that would be terrific!

Going to sound stupid, but is it possible to run that alt on the other side of the motor?

The belt contact on the crank pulley would be better, and raising the alt higher doesn't look like it would cause a problem. Even if you could rotate the alt upward in its current location would be very helpful.

I am a bit concerned the limited crank pulley contact as it currently is could cause short belt life if there is high demand on the alt.

Crank rotation is clockwise as looking at the picture.

The unique thing about alternators are their ability to run in either direction and still charge.
The cooling fan on it is designed to run in a clockwise direction, it could cause the alternator to run a bit warmer but, not much.
More belt wrap or contact is always a better thing.

You wouldn’t want to double back a V belt over an idler like your pic. Serpentine, yes, V belt, no. I know some lawn equipment does use idlers and pulley configurations that put pulleys on the flat part of a V belt, but they use belts made to work that way, regular automotive belts won’t last long set up like that.

Bamamav said:

You wouldn’t want to double back a V belt over an idler like your pic. Serpentine, yes, V belt, no. I know some lawn equipment does use idlers and pulley configurations that put pulleys on the flat part of a V belt, but they use belts made to work that way, regular automotive belts won’t last long set up like that.

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Hey Bama.... Thanks. I talked to a couple belt manufacturers today and you are right. There is a double sided V belt but not in the size I need. I'm gona answer everyone and then post what I feel is my best option.

gene49 said:

Going to sound stupid, but is it possible to run that alt on the other side of the motor?

The belt contact on the crank pulley would be better, and raising the alt higher doesn't look like it would cause a problem. Even if you could rotate the alt upward in its current location would be very helpful.

I am a bit concerned the limited crank pulley contact as it currently is could cause short belt life if there is high demand on the alt.

Crank rotation is clockwise as looking at the picture.

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Hey Gene....didn't sound stupid at all. My issue is that my vega cross steer box is on the DS. This alternator is pretty deep and I can't go mid way because it will be hitting the block, head ect. Too high and it will mess with the look of my nose piece. My solution post last after I answer everyone. Thanks

Old Iron said:

The unique thing about alternators are their ability to run in either direction and still charge.
The cooling fan on it is designed to run in a clockwise direction, it could cause the alternator to run a bit warmer but, not much.
More belt wrap or contact is always a better thing.

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So my motor runs clockwise and so will the alternator yes? Yah...I did have a problem with not enough belt wrap on another vehicle so I'd like to design that issue out of it. Thanks OI

Ok so I suppose I've given you guys a headache on yet another issue.... Geeze everything take so much thought.

So I finished the skim cut on the crank pulley so it lines up with the water pump pulley. I had to take a cut off the pocket to clear the damper washer.

I can get a 2nd pulley from HH to stack on the damper pulley and I'll run my alternator with that 2nd belt. The alternator bracket has a slot for adjustment.

The inside belt will run the water pump and I fab up a idler bracket off the motor mount bolting. The belt will have to be tensioned by pulling it towards the DS.... this way I'll be on the v and not on the flat. PULLING THE BELT OUTWARD OK? Hope so cause I'm running out of options and would have to leave it with poor wrap. I did talk to Eric at HH today and he said he did run his lower bracket for 40k miles without an issue.

Whadatink?

Sounds like a plan. You could put your idler pulley on something like a turnbuckle to put outward pressure on the belt. It will be just the same as having a ps or ac pulley in that spot.

Nothing wrong with taking time out to think through a problem. It will save hours of frustration later on if something doesn’t work right the first time.

Bamamav said:

Sounds like a plan. You could put your idler pulley on something like a turnbuckle to put outward pressure on the belt. It will be just the same as having a ps or ac pulley in that spot.

Nothing wrong with taking time out to think through a problem. It will save hours of frustration later on if something doesn’t work right the first time.

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Thanks for your help Bama!

Chrysler used a V bely idler pulley for a WP belt adjustment back in the late 1970s on the big block cars. The V belt pulley just replaces the flat pulley on the modern flat belt tensioners, and the belt would run in the V like your other pullies. The aftermarket parts companies offered a V belt pulley/bearing as a replacement part, might still be available.

These question threads get all of us old timers thinking again, nothing wrong with that, its good for us. Don't ever be sorry about that.

gene49 said:

Chrysler used a V bely idler pulley for a WP belt adjustment back in the late 1970s on the big block cars. The V belt pulley just replaces the flat pulley on the modern flat belt tensioners, and the belt would run in the V like your other pullies. The aftermarket parts companies offered a V belt pulley/bearing as a replacement part, might still be available.

These question threads get all of us old timers thinking again, nothing wrong with that, its good for us. Don't ever be sorry about that.

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Thanks Gene....thinking is good and keeps the brain working. When I slow down and get lazy I also seem to get stupid quick!

So here is the idler bracket I came up with. It'll mount and be a trace of the alternator bracket, shoot behind the damper with a hole for the timing pointer to stick thru and bolt to the lower motor mount bolt. The hole for that motor mount bolt will have to be elongated so when i tighten the alternator belt that will have to move....and then readjust the idler. I'll put the idler block on a slot with a jacking bolt and maybe drill the motor mount bracket for a stand alone bolt and spacer. I believe this will work fine.

Now I'll have to decide on 1/2" aluminum or 3/8 steel. If alumium I can have my guys at work run it on the CNC.

See anything I'm missing?