13.9/14mm vs 8mm

I’m thinking of switching from 8mm to 13.9/14. I always got decent life out of the 8mm, especially the star racer, but with this sbc I’m running now I can’t run the belt as tight as I used to. I e heard the 13.9/14 is more forgiving of a looser belt. Is that true?

standard helix 14-71 between 20 and 40 OD spinning less than 9k rpm.

 

More difficult to break a 14, yes. But it’ll do twice the damage when it does. You can run an 8 loose if you’re not detonating.

 

I forgot to mention the length problem. I just added 2” to the pulley to pulley center distance. I was using a 1440 and 65-50 and could move up or down with no problem. Now I put a 1600 on there and can basically run 68-58 and that’s it. I need to spin the blower faster but my timing wheel is barely bigger than the 68.

Seems like the 1543 or 1568 would let me get a little more od.

 

a lot of people will clearance the back side of the pulley next to the timing wheel. Especially if running a magnetic pickup, as to be able to get the pickup the right gap to work. So a bigger bottom pulley isn't a problem at all.

 

Templar, that occurred to me after I posted that it might be easier to get a bigger pulley and clearance it since I already have a pretty good pile of 8mm stuff. I’m probably going to change intakes and may add an inch so probably just stick to 8mm if there’s no big lifespan gain going to 14mm.

I broke another 8mm but I realized there’s something going on with my tensioner. Even though I’m tightening it like I always do it’s slipping. Thinking the aluminum has squished enough that the pulley is tightening on the insert instead of the aluminum but haven’t looked into it yet

 

Also look at the idler pulley stand, the piece that the idler sits on. After 4 or 5 years of use we found ours was curved on the back side where it sits against the plate allowing it to slip.