I will be playing around with plywood over this holiday weekend on a 72 455 in the shed.
Once everything is figured out in plywood the piece will go off to a CNC shop.
I will have 2 v belts. I don't want to go serpentine belt.
The first goes from the crank to the water pump, to a alternator, to a second alternator, then back to the crank.
The second goes from the crank, to the water pump, to the hydroboost pump, then back to the crank.
On both these belt loops I want to add a tensioner in a "flat" part of the belt. This will let me solid mount the accessories as well as giving me the option of adding another accessory to the second loop at a later time.
I like common parts so when stuff goes bad parts are easy to find. With that in mind I would like to use a tensioner off of a TBI 5.7 Chevy then simply use spacers to mount the pulley in place of the plastic junk.
Will a setup like this cause to much force on the accessory bearings?
i can't think of any use of a tensioner pulley on the back of a v belt, unless for a low speed lawn mower belt
not saying it can't be done, just never saw one in use
Don't know your set up but this is what I did on my 507" Cadillac. You have to locate the best place to install, fab up a mount and spacers if need be. I used a piece of 3/8" alum, cut it into a rounded corner triangle shape, drilled and rat tail filed a short slot for adjustment. I bought a 4" pulley from Napa.... (they have a ton of different pulleys) and used a couple of grade 8 3/8" flat washers for spacers.......works just fine.
I will have one of the tensioner brackets set up so the tensioner is flipped towards the motor and the other flipped towards the radiator which will allow the same part to push up on both belts even though they will both be right (or left) tensioner. I am going to try to use the same sized belt on both loops also. Less parts in my breakdown box that way.
As no of the accessories or brackets from the stock motor will be used I can raise or lower the Primary Alternator and/or Hydro boost pump raising the other accessories as well if frame clearance becomes an issue. It will take a bit of playing around with a tape measure and common belts.
At this point I just want to know if I using a layout similar to what I have envisioned is going to cause an issue.
In your pic the idlers are at the top, pushing out on the v-belts, correct? This is not the way to go. You want to push "in" on the belts to increase tension AND increase the footprint (or wrap) of the belts on the pulleys. Your scenario will be decreasing the footprint, this is not what you want to do.
Look at the idlers on most TBI set-ups. They push in to tension the belt.
Another issue I see is Alt #2 will not have much belt wrap. This will cause slippage as the alt. output increases.
Mark
I always heard that a tensioner pulley on the back of a v belt will wear the belt prematurely because v belts are not meant to flex that way. Serpentine belts are OK to be tensioned from the back side.
Here's a pic of the idler pulley arrangement I used in my car. Initially, I was worried about reduced belt life, but after about 750 miles or so, it's fine. However, I carry a spare belt just in case.
I am not as concerned with belt life as I am with bearing life.
I have separate charging circuits and dual batteries. One drive and one accessory. If the charging belt goes I can simply toss on a new belt, pull out the jumper cables, jump the Main battery off the Auxiliary battery and I am back to cruising in 10 minutes.
If the more important Air compressor and hydro boost belt goes the truck will loose air pressure slowly until it ends up on the bump stops with me having manual brakes/steering. Toss on a new belt on and I am golden.
What I am concerned about is that the two tensioners are pushing down on the water pump bearing. I am also using a 7 blade thermostatic fan to add to that bearing load.
Pulling the water pump is going to mean pulling the many bolts holding onto it and the accessory brackets/accessories.
It is not a huge job. Just will be a pain in the butt and not something I want to do more then once in 3 years.
If I switched the idler and tensioners around that would take the load off the water pump and onto the crank. I could then switch around the upper alternator with the air pump which would put the load on the less expensive and easier to find alternators.
The problem I see in your layout is applying tension to the back sides of V belts. V belts aren't designed to be tensioned from the flat side, so bending your belt around the pulleys, and then bending it the opposite way to tension them, will result in very short belt life. You need to lay the belts out so the tension is on the inside of the belts, not outside.
The belt pushing out (on the inside of the belt) was what I had in mind with the first setup. The tensioners would push up on the belt and not cause a huge amount of bearing load yet provide enough grip. The water pump would be wrapped around 40% between the two belts with the other accessories around 30%.
I could move the tensioners from between the water pump and first accessory to between the two accessories. This would give more wrap on all accessories yet lessen the load on the water pump. The grunt of the load would be shared between the two accessories on each side of the tensioner.
It seems like the fix. Any issue with this?
The two alternators are something I have been doing since a bad run of isolators. Running two alternators gives me more options and less headaches when parts do go bad.
What are you using for an isolator solenoid?.....You cant use a Ford type starter solenoid.....It has to be a constant use solenoid, like you can get at an RV dealer.
I am running a second alternator.
It gives me option of running a 24 volt aux system, 16 volt aux system, 2 batteries(with isolator) aux system, two 160 amp alternators, etc, while leaving the main charging alone and simple. Having options is good.
This engine is going in a daily driver. It is a manual transmission and I spend a good amount of time coasting. I don't want anything putting out amps being covered in slush, salt, and water. Giving up 5hp to keep the alternator up high vs in the dirt on a drive shaft driven accessory is acceptable in my book.
So here is where I am at with the tensioners pushing out on the belts.
Red is the main alt/ps
Green is the Aux alt/Air
Blue just shows how far the (black) tensioners are pushing out.
All the bearing load are on the accessories leaving the water pump with mostly stock loads.
Well because you insist on doing this the hard way.....Id' rather have a simple system that works then a complicated one that's easy to fix. Just run the second alternator off the crank using a mandrel drive. There are plenty of pre-made kits out there already. Your Welcome.
I think 30% contact in a pulley would be fine for the tensioners, but for anything that pulls a load, you might see some belt slippage under some situations.
I know you dont want to hear my opinion, but
1....those belts are going to be way too long. going to be slippage and throwing belts.
2....I dont see why you need tensioners and idlers. Run a double pulley on the water pump and crank. Have a belt going out each way to an alternator on each side. Keep it simple
I will try moving the accessories as close as possible to the block to lessen the belt length.
I need to have the hydro-boost pump for breaks(lower right) and york air pump (lower left) for the air tools and eventually air ride. I need one alternator and might as well mount the other one on the block to lessen the wiring.
I am thinking with this setup the tensioners will eliminate most of the slip on start up and when loads are applied better then just a sliding bolt system on both the alternators.
One other note, if it helps with layout. An alternator doesn't care which direction it turns to put out 12v. So it can be mounted backwards on the front of the engine, with pulley facing the engine, and still charge. I've seen rods with tight space requirements, and their alternators mounted this way, and work the same.
Yea, I have one running normal and the other flipped so that I could use a bolt hole that was set up for the AC in my current bracket. All you need to do is flip the blades so that the thing still stays cool.
Why the second alternator?
This afternoon drove around 80 miles all around town stopping at 12 or so places. Roughly an hour ago I watch as my dash lights dim along with the rest of my lights. The truck takes almost no juice to run with the 6al2 and magnetic pickup dizzy. It did crank slow until it fired followed by my inverter light going red indicating I am at 8 volts before the truck's battery was sucked completely down. I know I am going to get pulled over or worse if I even attempt going home without lights though.
I am a good 30 miles away from home. Not a cheap tow by any means.
I hook up the dead main battery to my aux battery with some 4 gauge jumper cables and wait 5 minutes. Crank the engine over and she fires to life. Turn on my lights and drive normally back to the house with the aux alternator charging the aux battery that was feeding the main battery.
With an isolator I would have ran the battery down then ran the aux battery down shortly after and I doubt I would have made it 20 miles with my original lights and 11 extra(not including roof) (194) bulbs.
The second alternator got me to the the house with no problem. I will take another car to the parts store tomorrow, hand over the junk alternator, get a new one, and have it in within 10 minutes of arriving home.
The ironic thing is that this afternoon I dug out some like new 12 foot 2 gauge jumpers I never use and I was planning to re purpose for the thickness, shot to the race parts store for some 2 gauge copper flat connections, hit Walmart for the screw style "squish"connect they have in the battery section for like $10, then to Napa to get another master disconnect.
If something like a alternator or a battery died with the temp in the single digits I will flip the switch inside the cab instead of playing around with jumper cables from one battery to the other.
It would have come in handy tonight instead of having me avoiding pot holes to keep the wires from coming off the connections. I tossed bungee's on them. But, using 8 feet 4 gauge jumpers was not the best of plans.
i did not know that. not that i'd use it, but useful information
i do think the op is creating a mountain out of a mole hill
if he can't maintain a simple battery isolator circuit
i imagine a double charging system will go to heck in a hand basket soon
With all the vehicles using dual batteries, and isolators, I tend to agree with you. I'd rather get a good isolator, and one great alternator, than have two alternators, and all that involves.
I moved the power steering pump(big circle) to the lower right and you can see where the added area in the lower left is enough to fit a York air pump if I play around with a flexible radiator hose. The smaller alternators are up high with one on each belt as much in front of the heads as I can make them work.
I need both belts to run everything no matter the configuration. I am trying to get my hands on a junk frame so I can cut it up and use the rails as a reference to find out where to put what(accessories, exhaust, mounts, oil pan, etc) eliminating as much wasted space and guesswork making what I plan to be a weekend drop a true drop with less chance of headaches.
You really don't need to flip the blades, and some wont allow flipping if the shaft is tapered. Air will flow either direction, so it either pushes or pulls.
Sounds like you need an idiot light on your alternator, so you'll know when it takes a dump. Or watch the gauges closer to know when it happens. I still don't see why one good working system,wouldn't be enough, if it was monitored and maintained. Millions of vehicles go along every day with a single system.
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