13.9 and 14 pulleys

Has anyone ever ran 14mm belts on 13.9 pulleys? What happened?

Boy, if there weren't stampings on pulleys how would you know the difference?

 

13.9-14

we ran 13.9 and 14 mm belts a pulleys with no problems... Roots Blower ... top pulley 13.9 bottom 14... BBC making 42 lbs of boost and SBC making 50 lbs of boost

 

13.9mm pitch = .5470"
14 mm pitch = .5515"
Difference = .0045"

 

I would think that it would be more of a problem if the lower pulley was changed
seeings how it is much larger than the top so the misalignment would show up more
as the belt will go around more teeth & gradually increase in mis alignment.
Whats your thoughts guys?

 

Mike, would there be no problems even in blown alcohol K boat racing for say 3 minute races sitting on 5500-8000 rpm. Just wondering if the extended period would have any effect, thanks.

 

Before I forget Mike, is there any problems going the other way, 14mm pulley with 13.9 belt

 

13mm belt with 14 mm pulleys

I got talked into trying the 13.9 mm belt on the 14 mm pulleys several years ago from a real good friend who had been racing blowers for years. Well sad to say first one broke after two runs second one broke first run. Messed up some parts in the process. When I asked him about it said he got confused and got it reversed and gave me some new 14mm belts his cost. The truth is what Mike said 13.9mm pulleys 14mm belt will get you by in a pinch. So I say just make sure the belt is a 14mm if you don't know what pulleys you have. Chuck