moehorsepower

iTrader: (3)

Well I now have proof that running a D1 with the 12 rib set up does cause bearing wear on the front main. I have heard from no they do not cause any additional wear to guys saying that every 8-10.000 miles they were replacing the mains, Well my LT1 had the D1 with the 12 rib setup. the motor probably has app. 4000 miles of street driving and a couple of track passes. I always had belt slippage so according to Procharger the belt had to be banjo tight. Had a mechanic check the mains since we were replacing the oil pan gasket and he told me that the front main was starting to show the copper wear and yes I ran Royal Purple with the Mobil 1 and K&N oil filters.

TS6

iTrader: (41)

And you verified proper tolerances and ruled out everything else before coming to this conclusion?

OUTLAWZ RACING

iTrader: (9)

I bet he did hell the car made 700+ on pump gas ran like a champ. And the person who is doing his work is top notch.

stevieturbo

Ive seen obvious signs of wear, with a little bearing crush at the outer edge.

You have a great big belt pulling hard on the nose of teh crank, and in my case with a lot of leverage. It has to place loadings on the bearings....especially on start up before oil gets moving.

DeltaT

iTrader: (5)

If you need a tight 12-rib, maybe you need a crank/blower brace too.

The front bearing wear thing is good to know - I'll put that on my list of stuff to watch for.

I wonder if there are any front bearings available that would better handle those loadings?

Jim

moehorsepower

iTrader: (3)

You can bet all clearances were checked, Rods, Mains, Rings, ect. The complete motor was blueprinted, everything deburred, timing chain, any casting flashes ect and yes the machinist is well known. He ONLY builds high horsepower motors, no stockers.One problem is that I did have one of the early setups by Procharger that had the weak brace and the supercharger would flex, this may be one contributing factor to having to have the belt so dam tight. But in my case, I had the so called balancer, a 4 inch spacer then the supercharger pulley. I kept thinking this was acting like a cheater bar at then end of the crank and had to have some adverse affects. Plus we had a vette with a F1 that broke the snout off the crank.. This is just some facts that I encountered and wanted to share. Oh and to get the correct facts it was 648 RWHP on Pump and 722 on the fast gas..

Old Geezer

iTrader: (3)

Brg wear and broken cranks were/are a common problem w/ roots blowers, too.
BBC snouts on SBC cranks, ft crank girdles, are ways folks try to minimize problems.
Tight belts w/ a cold blower: A hot blower, mounts, and the belt gets even tighter.