Thread: amount of belt wrap on sbc waterpump pulley

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I don't think this is gonna work very good!!!!! What you see is the sbc in my roadster pickup, with a short waterpump and an aftermarket alternator bracket. I had to go to the aftermarket alternator bracket to move the alternator because I couldn't move it back far enough to line up with the pulley on the shorty waterpump. (it hit the front of the passenger side valve cover) This aftermarket bracket allows the alternator to move back the required amount by moving it up and into the valley between the valve covers. But----look at the amount of wrap on that waterpump pulley. I plan on running an electric fan, but even so, will there be enough torque transmitted to the waterpump with this very shallow wrap angle to let the waterpump do its job? If anybody out there is running a similar setup with a basically stock sbc, let me know how it works please. I'm kind of in a quandry, because if I move the alternator to the bottom left the rear of it will hit my mechanical (stock) fuel pump, and if I move it to the bottom right, then its gonna get real cozy with my Vega steering box.

I've used this before, and it works fine. Doesn't appear to have much more wrap.

Denny, do you mean 35 degrees? 35% would be 126 degrees, and I don't think that much wrap is required. Just asking, because I haven't heard that rule of thumb before.

Denny---I think that your idea has merit, in terms of an idler pully to increase wrap on the waterpump pulley. I actually have more room for one between the waterpump pulley and the crank pulley, as you can see in the attached picture, plus there are 2 tapped holes in the block just to the right of the crank pulley that would form a good mounting point for an idler bracket and also be a bit more pleasing to the eye, as I plan on running no hood sides. Henry Rifle----Your set-up appears to have about the same amount of wrap as mine. Have you actually driven this car, or is it still in the building stage? The chassis and engine show some very skilled workmanship.

Denny and Henry---Just thought that I would clarify something a bit. I have built a number of rods in the past, and they all ran small block Chev engines. The cars I built before had custom frames which I designed, and consequently I allowed enough extra stretch in these frames between the firewall and the front axle that I was able to run factory stock front waterpumps and multi groove crank pulleys with no clearance issues. All I needed to do was fabricate a hood top and sides that were about 3" longer than stock. This time around, I'm trying to stuff everything into the space alloted by an unstretched model A frame. The firewall is recessed 4" in the engine area, but thats all the room I have available. I know that some of my questions may seem a bit naive, but its only because I haven't ran up against this type of clearance issue before. I am sure that there are hundreds of model A's running around with small block Chev engines and stock length hoods, and I appreciate the help you guys are giving me.

I have essentially the same set up on my 32. I am running two belts. Looks trick and seems to work fine. I have GM performance crank and pump pulleys. My alternator pully is something the guy who rebuilt my alternator had laying around. Fabricated my own alternator bracket. Sorry about the picture. Best I have on file.

Here's an alternator set-up I built on an A-bone sedan with a big block. It has about the same wrap, and never had a problem either.

Another view.

Bib_, I liked that picture back on the Vortec head thread and I
picked up on the double belt setup. I am also learning a lot just following Brian's progress. The question is, where can I begin to look for the double pulley for the alternator? (I already have the double belt pulleys for crank and short water pump.)

Don Shillady
Retired Scientist/teen rodder

Have you actually driven this car, or is it still in the building stage? The chassis and engine show some very skilled workmanship.

Brian,

I haven't driven this chassis yet, but it's the same setup I've used in the past. As Denny mentioned, you do have the advantage of having your alternator on the torque side. Yours is much more like my big-block setup in the later photos.

Thanks for the compliment, by the way.

csf,

I ran some quick measurements on my engine in the garage. If the alternator were mounted on the lower left, you would need a longer belt, you would have more wrap, and the top of the engine would be cleaner with less "stuff" up there. That's a common location in rods with sufficient space. There wasn't enough room in my A-Bone to do it, though.

Originally posted by DennyW
Hey, looks real nice. That's a great idea also about the double belts. It looks like they contact on both sides of the water pump pulley. Correct? That is a grabber setup.

The belts do not contact the water pump on both sides. About a half inch of clearance. I started by positioning the alternator for appearance and clearance and then I built the bracket to fit. I had to clear the Edelbrock fuel line, valve covers, etc. I could have positioned it a bit further to the passenger side, which would have improved water pump belt contact, but that would have compromised the "look". At shows the experienced rodders seem to focus on the alternator bracket. The gawkers focus on the inside door handles I fabricated from a $4 pair of Mr Gasket "8 Ball) door lock pulls.

They say the rule of thumb is 1/3 if the pully has to make contact with the belt.

Originally posted by Don Shillady
Bib_, I liked that picture back on the Vortec head thread and I
picked up on the double belt setup. I am also learning a lot just following Brian's progress. The question is, where can I begin to look for the double pulley for the alternator? (I already have the double belt pulleys for crank and short water pump.)

Don Shillady
Retired Scientist/teen rodder

Don,

When it came time to source an alternator I did not have the $100 for a polished aluminum model (well, I did but not for an alternator). So I had my friend Danny Liles rebuild an old core for me. He has been rebuilding alternators and starters at his parts store and has all kinds of stuff laying around. I suggest you check with an alternator shop to see if they have what you need. If you get a used pully check the groves for uniform wear. The first one we checked was deeply worn in one grove.

I did a quick web search and found this http://amkproducts.com/GM_alternators.asp . I am sure there are other sources.

Good luck.

Of all the various ideas for relocating the alternator, I like the idea of putting it down at the lower left the best. That would give great wrap on the waterpump pulley, leave a clean look to the engine, and with a little effort I could probably modify the aftermarket bracket that I ended up paying $82 for, to fit there. Only problem is, my mechanical fuel pump is in the way. You know, its all about money. So far I have spent $82 for the alt. bracket, and $48 for the 2-groove crank pulley, and $12 for the v-belt. I don't know what an electric fuel pump is worth, but I would hazard a gues that it would spoil $200. I have the money to spend, but my gut just kind of rebels at spending anything that I don't have to. This is a hobby for me, and so far I have about $11,000 invested, with probably another $5000 to complete it---$1000 for tires, baby moons, trim rings, $1000 for paint,$1000 for interior, etcetera. Is there any production vehicles that would be available at the wreckers which would have an electric fuel pump that would run in conjunction with a carburator? I simply don't know. I will probably take the approach that "run it as it is" and see if there is a problem. If not, then great. If so, then its not a big deal to change it after the fact. If other people are running the same set-up without experiencing problems, then I'll probably be O.K.

A Holley "Red" fuel pump will set you back $95.88 from Summit.

I think you're going to be fine with what you have. If not, it'll give you something else to do in a year or two.