[Bowtieracing]

Originally Posted by speedjohnston

I keep some info on hand that may help...

http://www.popularhotrodding.com/eng...exh/index.html

http://www.centuryperformance.com/ex...h-spg-137.html

http://www.chevyhiperformance.com/te...ech/index.html

if you read all that you'll still be confused. lol

How right you are.. But now i know how to measure primary size