LiteraCola

Good afternoon, guys. I've got an A&A kit coming soon with a V1 head unit. I found a great deal on one so I went for it! I've since been thinking... Back when I did my heads/cam build (Spring 2015) I went back with an OEM crank pulley with an ARP bolt. Everything was right as rain until the bolt decided to back out and I almost lost the pulley. I was naive and used the "special" ARP antisieze instead of Loctite. It made for an interesting time at Carlisle, thats for sure. Anyways, when I repaired it, i went back with a 25% UD Powerbond pulley and pinned it like I should have the first time. I never really planned on installing a blower, at least not for years and years (I've got a 2 yr old at home). When talking to Andy at A&A, I never really thought about the effect that an UD pulley will have on the base 3.8 blower pulley. I called him back later and was told that he could throw in the 3.4 pulley but the belt size would be a guess. I'm okay with measuring and experimenting with belts, but I figured I would ask you guys what you thought would be the best path to take. I could swap the crank pulley out for a stock one, but for the amount of work involved (and the fact that it's already pinned), I'd rather not do that.
I've also heard things about the extra lateral torque loads that a blower places on the crank, resulting in a broken crankshaft.
I came across a good belt guide that shows all the lengths and part numbers for Gates belts, so that helps. Looking at the A&A site, the belt that comes with the 3.8 pulley (assuming a stock crank pulley) is 91 5/8"....3.6 is 90 7/8"... and 3.4 is 90 5/8. There has to be some kind of formula that the car gods have devised to make this easier...
Has anyone run into this before? Thanks!

Turpid porpoise

You can always use a length of string to wrap the pulleys and then measure the string to get your belt size.

LiteraCola

Isn't there a manual tensioner on the blower bracket to adjust for that? I don't know how much adjustment is there. This is my first experience with a blower install.

Turpid porpoise

There is a manual tensioner but you can still measure the length with a string. Once you install the belt you tighten the tensioner to get proper belt tension.

StuntHeavy

I measured mine, ordered, and was still wrong.

Seems a lot of people buy a few different sizes and return the ones that don't work for them.

Cutlassmaster

How much shorter is your UD belt compared to a stock belt? Take the difference and subtract that from a stock blower belt to come up with what you need. At least that is what i would do but that is only logical to me.
Chris

silver408z

The smaller crank pulley will also decrease your belt wrap. I am having a procharger installed on my car and went with an OD pulley to increase boost and belt wrap.

stryderss

https://www.corvetteforum.com/forums...ewter-pig.html

yes if you happen to be running a v3 si or T trim and have a 25% underdriven balancer and a 3.6 blower pulley then A GATES K060878 is the belt you will need to run, could run the K60874 too. want to grab a J bar and see if i can get it a little tighter

should work for a 3.8 also

hope this helps

LiteraCola

As i said, A&A is going to send my blower with the 3.4 pulley and "guess " at the belt size. If it's too small I'll try the tensioner holding trick and see what happens! It'll be a little while before I install it anyways! Thanks for the suggestion!

LiteraCola

I guess if I run into issues I can go through the trouble of swapping out the crank pulley. Damnit.

LiteraCola

After much discussion with my tuner and Andy @ A&A, I've decided to err on the side of caution (and my sanity) and just swap out the UD pulley for a stock one. It's another few hours of work, but this'll be the third time I've done it, so I'm getting very efficient at it! That way, there's no guessing when it comes to belt size or pulley size. Strap it on (giggity) and go!