I just finished building a factory team b4.1 kit with a novac 13.5 spec motor. The owner of our local indoor track told me to gear it at 75-23. The track is high grip and very tight. Does that sound right? Sounds odd to me but he owns the track and I have no reason to doubt him. Just wanted to know if any one else runs that gearing on a high grip tight track. Thanks

That sounds really under-geared. Check out the web site comeseethis.com
It looks like a 26 or 26 tooth pinion would be the best fit for your 75 spur.