LS3 - Picking Alternator Mount and Tensioner

[wesinls]

If you havent noticed by other questions I've asked recently - I am new to the whole LS engine scene and more or less trying to figure things out along the way...I have no issue admitting I'm new and know nothing.

The LS376/525 crate engine does not appear to come with an alternator bracket (and alternator of course) - nor does it appear to come with the tensioner.  From what I can tell there are several different variations for the alternator bracket depending upon where you want it to end up and several options for the tensioner.  The manual tensioner seems like a good idea / less flop.  Below is what I'm thinking...first pic of crate engine.
Questions - what do others use? How do you determine the belt size after ordering these parts, whether it be the below or a different brand / versions?  When searching on Summit i put it's for a LS376/525, should I assume spacing will be correct / line up with other pulleys?

 

[Sandkist]

Katech makes a nice solid tensioner

https://shop.katechengines.com/product/car-billet-belt-tensioner/

 

[Chingon619]

Jason @ Alper motorsports he's also a member here. 

@

 

[Fullthrottleguy]

Jason @ Alper motorsports he's also a member here. 

x2 Hit up @J Alper he makes some really nice and strong Alternator mounts - just keep in mind  - location will determine to somewhat whether it fits your chassis.

Solid Tensioners are good on NA engine and if you use a good quality belt  and don't have PS  its likely you will only adjust it once a season or less.  I still prefer automatic tensioners especially with PS, no maintenance and on NA engines a good quality one will last a lifetime  and you won't "forget" to adjust it 

 

[Kevin]

i bought the ict stuff for my ls build.

 

[Squatcher]

Buy a good alternator  for sure.  Don't use a larger pulley on the alternator either.  Use the pulley that comes with it.  There are some real good ones out there in the $350 range.  200amp at idle is a good start.  

 

[J Alper]

The alternator mount we have, is more beefed up for Off-road, and our Tensioners bolt to the pump and to the head, way more rigid, 

 

[realtreeHD]

The alternator mount we have, is more beefed up for Off-road, and our Tensioners bolt to the pump and to the head, way more rigid, 

Can you pm a price?  Also which alternator do you run?

 

[KLC]

You will first need to determine what crankshaft pulley your engine will use, this will establish the positioning of all the accessories. You will need to know if you are going to use a p/s pump or not, an idler will need to be installed in it's place if you will use electric steering. The alternator bracket and spacer are also dependent on which crankshaft pulley you have. ICT and DirtyDingo make good bracketry. I personally like to use a Gates spring loaded tensioner because they just plain work well, mine has been in use for 3 years now and the tension indicator has not moved at all it is just as strong as when it was put on new. A solid tensioner is ok I guess but unless you are revving to extreme RPMs it is just not necessary IMO.

As far as which alternator you will use, the simplest way is to use a single wire alternator and use a resistor from Holley to power it up. I bought my alternator from a place in Glendale Az called Gen-Star, they build them with the highest quality internal parts and bearings, then test them for output. Mine is a 100a unit and makes a consistent 14-15 volts all the time. I hear all of the blah-blah-blah about high voltage and what not but I have zero issues within my electrical system and my battery stays charged. 

For the belt, mount all of the accessories and use a piece of electrical wire around all of the pullies and them measure it, OReillys auto parts will have several belts shorter and longer to choose from. When you find the belt that puts the tensioner in it's sweet spot, buy 2 of them and keep the spare in your tool bag. Fwiw I keep a spare alternator and both idlers in the moho although I've never had to use them. When I get around to it I want to get a spare water pump also.  Everyone in our dune group (except me lol) has needed an idler and water pump at least once in the last 3 years, it's nice to have on hand.

Also just a thought...if you go with the most compact Corvette spacing it puts all of the accessories way closer to the block and eliminates a lot of vibrations and such. This IMO goes a long way to making your accessory drive more robust and the possibility of having the belt roll off of the pullies at higher RPM. And when installing anything to your engine block use a quality torque wrench to tighten it to the appropriate specs, those threads are aluminum and the steel bolt is much harder and will pull them right out if you get heavy handed with your tools. 

Here’s what I have had good luck with.

 

[J Alper]

You will first need to determine what crankshaft pulley your engine will use, this will establish the positioning of all the accessories. You will need to know if you are going to use a p/s pump or not, an idler will need to be installed in it's place if you will use electric steering. The alternator bracket and spacer are also dependent on which crankshaft pulley you have. ICT and DirtyDingo make good bracketry. I personally like to use a Gates spring loaded tensioner because they just plain work well, mine has been in use for 3 years now and the tension indicator has not moved at all it is just as strong as when it was put on new. A solid tensioner is ok I guess but unless you are revving to extreme RPMs it is just not necessary IMO.

As far as which alternator you will use, the simplest way is to use a single wire alternator and use a resistor from Holley to power it up. I bought my alternator from a place in Glendale Az called Gen-Star, they build them with the highest quality internal parts and bearings, then test them for output. Mine is a 100a unit and makes a consistent 14-15 volts all the time. I hear all of the blah-blah-blah about high voltage and what not but I have zero issues within my electrical system and my battery stays charged. 

For the belt, mount all of the accessories and use a piece of electrical wire around all of the pullies and them measure it, OReillys auto parts will have several belts shorter and longer to choose from. When you find the belt that puts the tensioner in it's sweet spot, buy 2 of them and keep the spare in your tool bag. Fwiw I keep a spare alternator and both idlers in the moho although I've never had to use them. When I get around to it I want to get a spare water pump also.  Everyone in our dune group (except me lol) has needed an idler and water pump at least once in the last 3 years, it's nice to have on hand.

Also just a thought...if you go with the most compact Corvette spacing it puts all of the accessories way closer to the block and eliminates a lot of vibrations and such. This IMO goes a long way to making your accessory drive more robust and the possibility of having the belt roll off of the pullies at higher RPM. And when installing anything to your engine block use a quality torque wrench to tighten it to the appropriate specs, those threads are aluminum and the steel bolt is much harder and will pull them right out if you get heavy handed with your tools. 

Here’s what I have had good luck with.

View attachment 28875View attachment 28876View attachment 28877

This is a good example how things are not done correct,  

This is a Y body with F body brackets, This setup will have to grind on the Alternator or on the block to get the alternator back far enough to line up with the balancer 

Spring loaded tensioners can fail under hard jumps, or belt whip, you can see the Street Alternator brackets have very little material in the area of the smooth tensioner and can cause belt walk, 

 

[J Alper]

Beefy bracket we make 

our tensioner also bolts to the head for Zero Flex 

 

[KLC]

This is a good example how things are not done correct,  

This is a Y body with F body brackets, This setup will have to grind on the Alternator or on the block to get the alternator back far enough to line up with the balancer 

Spring loaded tensioners can fail under hard jumps, or belt whip, you can see the Street Alternator brackets have very little material in the area of the smooth tensioner and can cause belt walk, 

What you have posted is the reason I don't contribute here much anymore, I try to be positive and post something that may be helpful and there's always someone who posts right up behind me and says no that's not how to do it, or that will never work, or in this case making a mockery of someone's well intentioned post.  There was no material removed from the alternator or the engine block.  I still stand behind my post as being 100% accurate whether J Alper wants to agree with it or not. 

So where was the material removed to make this fit smart guy? You have just demonstrated that you don't know as much as you think you do.





 

And while I'm at it, this accessory drive doesn't use a smooth tensioner, that's a fixed idler so that the belt will wrap around the crank pulley and not slip. The tensioner uses a grooved pulley. This belt is definitely not walking back and forth. Again know what you're talking about before you post such nonsense. 




 

 

[r3meyer]

What you have posted is the reason I don't contribute here much anymore, I try to be positive and post something that may be helpful and there's always someone who posts right up behind me and says no that's not how to do it, or that will never work, or in this case making a mockery of someone's well intentioned post.  There was no material removed from the alternator or the engine block.  I still stand behind my post as being 100% accurate whether J Alper wants to agree with it or not. 

So where was the material removed to make this fit smart guy? You have just demonstrated that you don't know as much as you think you do.

View attachment 28961
View attachment 28962

View attachment 28963
 

And while I'm at it, this accessory drive doesn't use a smooth tensioner, that's a fixed idler so that the belt will wrap around the crank pulley and not slip. The tensioner uses a grooved pulley. This belt is definitely not walking back and forth. Again know what you're talking about before you post such nonsense. 

View attachment 28964

View attachment 28965
 

Thanks for posting.  I was trying to find an idler bracket to take the place of where the power steering pump went now that I switched to electric power steering.  Now I know where to get it.  Cheers!

 

[J Alper]

On a Y body this will keep from touching the block

 

[Rockwood]

Measuring the belt: I usually take the stock belt, cut it in one spot, route it as I want, then measure how much overlap or gap there is to get a starting point.  With an automatic tensioner, you'll have some variables on how long a belt to run to make sure it's tight, but still capable of being installed.  If you have a friend that can hold the tensioner, adding an inch to the length when holding the tensioner is usually enough to get the belt on without a lot of cursing.

If manual, just run it almost all the way out, route, and that's your measurement.

 

[J Alper]

Measuring the belt: I usually take the stock belt, cut it in one spot, route it as I want, then measure how much overlap or gap there is to get a starting point.  With an automatic tensioner, you'll have some variables on how long a belt to run to make sure it's tight, but still capable of being installed.  If you have a friend that can hold the tensioner, adding an inch to the length when holding the tensioner is usually enough to get the belt on without a lot of cursing.

If manual, just run it almost all the way out, route, and that's your measurement.

That is a perfect way to do it,   we have a super long belt and wrap it around then mark it with a paint marker, then measure out the lenght, 

for some that do not know, 

the numbers on the belt will equal the length for example K06 is 6 rib K08 is 8 rib and k10 is 10 rib 

K060780 is a 6 rib 78''  K061115 would be a 6 rib 111.5 inches,  

 

[KLC]

On a Y body this will keep from touching the block

View attachment 29044

Why did you post that my accessory drive is an example of how not to do it? Is it because I didn’t use your brackets? 

 

[HydroPower]

Does anyone have a source for a heavy duty auto tensioner for use on a supercharged setup? Needs to fit the camaro beltline config

 

[lincster]

Does anyone have a source for a heavy duty auto tensioner for use on a supercharged setup? Needs to fit the camaro beltline config

superchargersonline.com will help you.  Ask for David.