Blower Pulley Mounting

Does it matter which way you mount the top pulley on the snout? I'm told the cupped end should be over the snout but to get more setback, I would like to mount it with the cupped end out. Its an RCD 8" snout and I know it will add stress but where? They make 12" snouts so the blower case should handle it. Pulley will see the same load either direction so is the weak link the snout itself? Only going 20 to 30% overdrive.

 

by no means an experts view but;

I would say if you mount the cupped end out it increases the bending moment on the snout/snout to pulley mount (B = Force x Distance) in reality if failure were to occur it would be the mounting of the pulley to the snout that would break, to run more setback use a longer snout, designed with the forces in mind and therefore strengthened appropriately

 

I'm not an expert either... i do see how it would apply more pressure to the front snout bearing via leverage. but otherwise in my mind it's not much different than the loads/stress applied to the lower pulley? like to hear some input on this. especially from a certain california based blower guy who frequents here... i won't drop names... haha. =) sean

 

I see there being leverage applied to the bearings in the snout withthe pulley on backwards. Leverage = Stress. IMO

 

simply because the distance from the end of the blower snout/front cover to the load (ie; blower belt) is longer which increases the bending moment acting on the snout

the pulley mounting further forward will act like a longer lever

 

Make a snout support, clamped to the snout same way a conrod is bolted together, 3/8 thick ali will work fine. Bolted to the front of your motor in a place thats out of harms way, this will give your snout plenty of support & also take the pressure off of the front cover. Also a pulley spacer could help a little in lieu of a longer snout.

 

Agreed. That's what we have on the Nostalgia Top Fuel car.

EDB

 

Thanks for the idea!

 

Just my opinion, Iwould spend the money on a longer snout. The lower pulley works out ok bolted the way they do because you have the support of the balancer. I would think the top pulley on upside down would flex like crazy. Maybe I'm wrong? might work with lower overdrive. Kevin

 

Didn't work for me

I did exactly what you are thinking of with a 5" snout. Bolted pulley on backwards and it kept destroying the bearings in the snout. I made a longer snout and mounted it the proper way and no problems. And yes, I ran a snout support running down to the motor plate.

 

I Put My Wheels On Inside Out On My Junker When I Was A Kid. Didn't Take Them Long To Fall Off. The Physicists Have It: Longer Lever Means No Good Will Befall You. Good Runs To All Who Try.

 

how much does overdrive % play into this? for those that have had issues what percentage were you running? now i'm curious