Well that makes sense because on the 383 we didn't gain much from going to the bigger heads and cam. Same exhaust system then and now.PRH wrote: ↑Mon Jul 29, 2019 12:32 pm20+ years ago I built a high CR 406 with AFR 210’s, roller. Vic jr, Etc.
Went in a 65 Chevy II street car.
4.30’s, 9”, glide, 28” tires iirc.
Had 1-3/4x3 headers, 3” pipes into 3” flow masters coming out in front of the rear tires.
Mid-10 second car.
Remove pipes and muffs...... picked up .3 in the 1/4.
I'm having a tough time getting my friend to give it a try with open headers.