BBC crank hub on LT1?

[Fire67]

How would this be set-up? I mean, as far as the accessory drive pulley's and blower pulley's are concerned....
If I build a blower LT1 with a custom crank featuring a BBC crank hub for strength, what will be required to adapt a crank pulley that will line up with the stock accessory pulley's?

['68SuperchargedLT1Camaro]

Good idea Fire67. This is just about the only way to guarantee against crank snout failure on a serious supercharged setup.

You'll probably need to use an ATI LT1 harmonic ballancer with an ATI big block hub. If I remember correctly, all the hubs will mount to any of the balancers, so you can mix and match them. The balancer should come with a shim to adjust the allignment, depending on which LT1 accessory set up you have (F-body or Y-body).

I'm using an ATI balancer with a custom made hub. The inner diameter of the hub is that of a normal small block chevy hub (I'll be using a standard size small block crank snout), but the outer diameter is similar to that of a big block chevy hub. This basically just gives me a tougher hub, that isn't as prone to splitting along the keyway, but I still haven't eliminated the problem of snout failure. I'll just keep my fingers crossed. I haven't had a snout break off, but I have had hubs spin off the crank, and destroy it. This is why I switched to the custom double keyed hub.

Here are a few pics of my balancer:

[Fire67]

So, did you need a custom blower drive pulley to bolt up to that ATI balancer? Or is that the purpose of those 3 12-point bolts?
I think I will do everything I can to adapt the bbc crank snout setup on my motor build, Even if it costs a fortune... I just do not want to have a crank snout shear off, I'd be awfully depressed afterwards.
AggieZ28: had this done on her motor that's for sale... Aggie if you see this thread, I'd love some input.
Raymond: thats a nice balancer and thick ss hub!!

['68SuperchargedLT1Camaro]

fire67 said:

So, did you need a custom blower drive pulley to bolt up to that ATI balancer? Or is that the purpose of those 3 12-point bolts?

I think a Vortech crank pulley would bolt right up, but I'm not sure. I'm having custom made pulleys, so I didn't check the Vortech pulley. The crank pulley I intend to have made will actually bolt to the back side of the balancer, under the waterpump. I've never seen a set up like this before, but I've been chatting with a few of the guys over at ASP, and we think we can make it work.

fire67 said:

I think I will do everything I can to adapt the bbc crank snout setup on my motor build, Even if it costs a fortune... I just do not want to have a crank snout shear off, I'd be awfully depressed afterwards.

Your on the right track. A BBC crank snout is a GOOD idea. My balancer was $571 if I remember correctly. You should be right there at that price, because you'll basically have the same thing: ATI LT1 outer shell with a custom made hub.

Raymond

[1bad2k2ta]

admin said:

I think a Vortech crank pulley would bolt right up, but I'm not sure. I'm having custom made pulleys, so I didn't check the Vortech pulley. The crank pulley I intend to have made will actually bolt to the back side of the balancer, under the waterpump. I've never seen a set up like this before, but I've been chatting with a few of the guys over at ASP, and we think we can make it work.

I have never seen this configuration before. How do the tensioner and idler pulleys (if any) fit in? Got any pics? Also, if you break or wear the s/c belt, won't it be more difficult to put on a new one? Pulley alignment will need some careful scrutiny.

[Fire67]

Behind the main crank pulley? How many rib belt are you gonna run? I cant see my 12-rib fitting back there at all. I was looking at ATI's catalog and it says they do custom pulleys for different apps with the blower pulley built into the balancer pulley
Maybe I'll go that route and get a LT1 super damper with the procharger 12-rib drive pulley built onto it. As long as its not too expensive, I've got alot of motor parts to buy.
<EDIT> I almost forgot that your gonna run a dual sync distributor... No Opti-Crap = more room

[Alex94TAGT]

Sheesh, Raymond -- that ATI damper hub looks Hulk-ish. Will you still be using the factory timing cover (machined)?

I was originally intending to use my keyed factory hub, but now you guys have me worried. No doubt, it'll probably crack on me. Are the 'standard' ATI hub/dampers prone to such problems? Or are you guys overbuilding it 'just in case'?

[Fire67]

I wouldnt say its the standard ATI hub/damper we're completely worried about... Im wanting to go BBC crank snout just because Ive heard of blowers causing enough stress on a SBC snout to shear it off. Ray seems to have come up witht the idea of using the thicker hub (BBC outside diameter) to help strengthen the area all together. He's still got SBC snout size, but I can see that thicker hub w/dual keyways strengthening the assembly quite a bit.
Alex, If I were you... Id definitely look into at least having dual keyways, and since you already have your crank (I think) w/ SBC snout it would probably be a good idea to get the thicker hub to protect it some from distortion/stress

[Alex94TAGT]

Thanks for the info, Justin. I appreciate the help, and I'll definitely look into it~

Man, these buildups are a neverending money pit, aren't they?...

['68SuperchargedLT1Camaro]

1bad2k2ta said:

admin said:

I think a Vortech crank pulley would bolt right up, but I'm not sure. I'm having custom made pulleys, so I didn't check the Vortech pulley. The crank pulley I intend to have made will actually bolt to the back side of the balancer, under the waterpump. I've never seen a set up like this before, but I've been chatting with a few of the guys over at ASP, and we think we can make it work.

I have never seen this configuration before. How do the tensioner and idler pulleys (if any) fit in? Got any pics? Also, if you break or wear the s/c belt, won't it be more difficult to put on a new one? Pulley alignment will need some careful scrutiny.

Sorry Tom, I didn't notice your post.

I haven't decided on the exact locations for any of the components yet. I only have a pic of the blower suspended in the general area that it will be located.

Yes, it will be harder to replace a blower belt in the event of wear or breakage. I'll have to remove the serpentine belt everytime.

['68SuperchargedLT1Camaro]

fire67 said:

Behind the main crank pulley? How many rib belt are you gonna run? I cant see my 12-rib fitting back there at all. I was looking at ATI's catalog and it says they do custom pulleys for different apps with the blower pulley built into the balancer pulley
Maybe I'll go that route and get a LT1 super damper with the procharger 12-rib drive pulley built onto it. As long as its not too expensive, I've got alot of motor parts to buy.
<EDIT> I almost forgot that your gonna run a dual sync distributor... No Opti-Crap = more room

Surprisingly, it appears that a 12-rib will fit. I won't know for sure until the motor is built, and the ATI balancer is installed. I'm only planning on a 10-rib. Companies like GoodYear and Gates make 10-rib belts in alot of different lengths.

The supercharging specific balancers that I've seen from ATI have a cogged style pulley on the front. I've never seen them with a serpentine style pulley.

['68SuperchargedLT1Camaro]

alex94tagt said:

Sheesh, Raymond -- that ATI damper hub looks Hulk-ish. Will you still be using the factory timing cover (machined)?

I was originally intending to use my keyed factory hub, but now you guys have me worried. No doubt, it'll probably crack on me. Are the 'standard' ATI hub/dampers prone to such problems? Or are you guys overbuilding it 'just in case'?

The standard ATI hubs are prone to cracking in supercharged setups.

[1bad2k2ta]

admin said:

fire67 said:

Behind the main crank pulley? How many rib belt are you gonna run? I cant see my 12-rib fitting back there at all. I was looking at ATI's catalog and it says they do custom pulleys for different apps with the blower pulley built into the balancer pulley
Maybe I'll go that route and get a LT1 super damper with the procharger 12-rib drive pulley built onto it. As long as its not too expensive, I've got alot of motor parts to buy.
<EDIT> I almost forgot that your gonna run a dual sync distributor... No Opti-Crap = more room

Surprisingly, it appears that a 12-rib will fit. I won't know for sure until the motor is built, and the ATI balancer is installed. I'm only planning on a 10-rib. Companies like GoodYear and Gates make 10-rib belts in alot of different lengths.

The supercharging specific balancers that I've seen from ATI have a cogged style pulley on the front. I've never seen them with a serpentine style pulley.

What about using 2 6-rib belts? You would get better grip and if one breaks, you still have another to keep you running until you can get replacements. Plus 6-ribs are way cheaper. Would that work, or would they wear each other out?

['68SuperchargedLT1Camaro]

fire67 said:

I wouldnt say its the standard ATI hub/damper we're completely worried about... Im wanting to go BBC crank snout just because Ive heard of blowers causing enough stress on a SBC snout to shear it off. Ray seems to have come up witht the idea of using the thicker hub (BBC outside diameter) to help strengthen the area all together. He's still got SBC snout size, but I can see that thicker hub w/dual keyways strengthening the assembly quite a bit.
Alex, If I were you... Id definitely look into at least having dual keyways, and since you already have your crank (I think) w/ SBC snout it would probably be a good idea to get the thicker hub to protect it some from distortion/stress

The only reason for the larger outer diameter hub is to avoid cracking at the keyway, as seen in the previous pics.


It's obvious from this pic that the custom hub will be much stronger:



Getting a hold of a small block chevy crankshaft with a big block chevy crank snout isn't absolutely necessary, but it's a good guarantee that you won't snap the snout off the crank with a super high boost supercharged setup.

With my setup, part of the reason to place the crank-supercharger pulley behind the balancer is to put less stress on the crank snout. With the pulley in this spot, it has less leverage on the snout.

['68SuperchargedLT1Camaro]

1bad2k2ta said:

admin said:

Surprisingly, it appears that a 12-rib will fit. I won't know for sure until the motor is built, and the ATI balancer is installed. I'm only planning on a 10-rib. Companies like GoodYear and Gates make 10-rib belts in alot of different lengths.

The supercharging specific balancers that I've seen from ATI have a cogged style pulley on the front. I've never seen them with a serpentine style pulley.

What about using 2 6-rib belts? You would get better grip and if one breaks, you still have another to keep you running until you can get replacements. Plus 6-ribs are way cheaper. Would that work, or would they wear each other out?

This has crossed my mind (I was actually thinking about it earlier today), but I'm not sure how well it would work. It's an option I'm considering.

If I can in fact fit a 12-rib setup, and I can find a 12-rib belt in the correct length, I'll do it, and test out the dual 6-rib idea.

[1bad2k2ta]

admin said:

fire67 said:

I wouldnt say its the standard ATI hub/damper we're completely worried about... Im wanting to go BBC crank snout just because Ive heard of blowers causing enough stress on a SBC snout to shear it off. Ray seems to have come up witht the idea of using the thicker hub (BBC outside diameter) to help strengthen the area all together. He's still got SBC snout size, but I can see that thicker hub w/dual keyways strengthening the assembly quite a bit.
Alex, If I were you... Id definitely look into at least having dual keyways, and since you already have your crank (I think) w/ SBC snout it would probably be a good idea to get the thicker hub to protect it some from distortion/stress

The only reasoning behind the larger outer diameter hub is to avoid cracking at the keyway. It's just a stronger hub.




Just about the only ways to help avoid snapping off a crank snout (without using a brace) is to use a crank with a bigger snout. The BBC crank snout on a SBC crank isn't absolutely necessary, but it's extra insurance.

Part of the reason to add the crank/supercharger pulley behind the balancer is to put less stress on the crank snout. With the pulley in this spot, it has less leverage on the snout.

d@mn, now you have me worried. I have the ATI SuperDamper on mine, too. Will the BBC hub fit a LS1 crank? The last thing I need is that thing coming loose and scarring the shiznit out of that high $ Lunati crank.

['68SuperchargedLT1Camaro]

I have no idea if it will fit an LS1 crank or not. You could have a hub custom made with the larger out diameter. You would just have it made with the stock LS1 inner diameter.

I don't know how common it is for the standard ATI hubs to split. I've never personally had a keyway split on me, but those pics scared me into buying a custom hub. I've heard that it's only an issue with setups above 10 psi, or cogged belt setups.