How tight can belts be? And other pulley Q's

[jamyers]

Just added a/c to my '62 Ranchero 170 (yippee!)

The kit uses the original 1-groove crank pulley to drive the water pump then a/c compressor, and the (new) alternator is driven from the a/c compressor's 2nd pulley groove.

Problem is, I've got the a/c compressor pretty darned tight (about 3/8" deflection), but the belt still slips a second or two when it engages, because the water pump pullet is deflecting "just enough" when the initial load "hits".

1. How much can I tighten the a/c and w/p belt before I start causing problems for the water pump bearings?

2. Is there a heavier-made w/p pulley out there I could look for?

3. Should I look for a 2-groove crank pulley, and engineer a way to have the crank pull the a/c compressor directly, without loading the w/p?

I like to run belts my belts on the loose side, the idea of a REALLY tight belt eating away at the water pump bugs me. Or should I not worry?

 

[Junk-Falcon]

try

 

[jamyers]

Tried that today at lunchtime, it worked for about 10 minutes. The belt is right on the verge of slipping, it squeals for 2-3 seconds after starting, and at random intervals while driving around.

I'm going to try and tighten it a little more, maybe the new compressor will loosen up a bit after some wearing in...maybe the belt will stretch out and get grippy...maybe a suitcase full of money will fall into my lap.

Might be enough room for an idler pulley between the w/p and a/c, to gain some more "wrap" around the a/c pulley. hmm...

 

[Anonymous]

Some 70's fords had an A/C compressor with a large "flywheel" clutch, that might help.

If you are running el cheapo belts, throw them away and get good Gates or Goodyear belts.

What compressor are you running? I have a complete "front-end dress" accessory set-up from a '82 if you need one.

 

[Lazy JW]

That's a lot to expect from one little belt. Definitely use a top quality belt. Belt dressing is just a band-aid, we use it sometimes in the sawmills to help a worn-out belt keep going until next breaktime when it can be replaced. Proper mainetnance and design eliminates that problem though. Getting more wrap around the pulley looks good at first glance but tha idler would need to be bodaciously strong because it will be carrying the brunt of the thrust. You already have a three point drive setup (crank pulley-water pump-A-C pump). An idler that icreases wrap aound a pulley is normally used on the slack side of the belt. So as not to be working against the pull. If you engineer it stout enough, it would help slightly. Or just tighten the belt some more and wait for the suitcase of money Dual belts would solve it better.
Joe

 

[CZLN6]

Howdy Jamyers and All:

There is an AC water pump available. I know that one difference is that the impeller is shrouded to increase water flow, I do not know if the bearing area is more substantial.

And the only ones I've seen have been for late model engines with the long shaft. IIWY I'd head down to the parts store for a new quality belt and check on the availability of a short shaft AC water pump, say for a '65 200. I say a '65 200 Mustang/Falcon because I know that AC was a factory option in that year.

Adios, David

 

[jamyers]

Thanks for all the info, everybody! Here's where it's at this morning:

Compressor is a new Sanden, the belt is a new Dayco (in my experience, Dayco belts tend to be a little 'grippier' than Gates, at least on farm equipment.)

Water pump is a new shorty pump, there's not near enough room for a long pump. I couldn't find an impeller difference between a/c and non-a/c shorty pumps from any local stores (AZ, PerpBoyz, NAPA, PartsAmurica, CarQuest), only shrouded impellers on long pumps. (?)

Checked the belt again last night, in one day it had stretched from less than 3/8" deflection to over 1/2". Tightened it again to just under 3/8", it's currently gripping. The water pump pulley doesn't visibly deflect, I guess that movement I saw was only when initially tightening the belt. Still, a good machined pulley might be better...

Hopefully the belt is just stretching more than I'm used to. (belts on my old Buick last forever, so it's been awhile since I've done a new belt...) I'll drive it for awhile, and if it's done stretching, I might back it off in a week or so and see what happens.

After looking, I don't think an idler pulley would work well, for the reasons stated above by Lazy JW. There's room underneath between the compressor and crank, but nowhere easy to bolt it up to.
If need be, I think the easiest/best solution would be to get 2-groove crank and w/p pulleys, and run the a/c compressor by its own belt, and the water pump with its own, each straight off the crank. Only issue I could see there is I'd have to unbolt the w/p pulley & fan to get its belt on/off, but since there's not much load there, belt tightening wouldn't be as critical.

Thanks again, I'll let you all know how it works out...I love this board!

 

[pedal2themetal45]

Don't forget the Alternator off the water pump.
Tim

 

[jamyers]

The new a/c bracket mounts the compressor where the generator used to be, and the alternator (converted) goes right above it, driven off the compressor.

That IS a lot to ask for one belt, but it seems to be doing well so far...(fingers crossed)