more blower belt probs

We run a Big Chief Chevy with 14-71 superman HH@ 34% od. We recently started breaking belts (14mm) at several different places on the track. The tuneup is getting lean but it seems to be happy(big mph) with a lot of the cad burned off the plugs. We only have 10-1 compression.
A couple of ideas we're kicking around...
We use a msd promag with burnout rev limiting.Seems hard on the belt.
Leaner tuneup is making a very lean spot that is not reflected in the data.
Idler pulley does not have double support like the RCD setup.
We haven't checked the rod bearings yet.
We always ran fat safe tuneups and never had a belt issue, but we never outran anybody either.
Thanks for any ideas,
Mike

 

Why not use a throttle limiter on the burnout to keep it off the chip? Running on the chip during a burnout or any other time is hard on valves and springs ( Harmonics) are you sure your good there?


Just my two cents,

Richard Gavle