My 71 is mostly stock:
Original block, heads intake
068 cam, 3/8 polylocks
original points distributor
std bore
close ratio M22 replaced with wide ratio (2.52 1st) gears.
non original carb.
My timing was set at 9 degrees, so I bumped it up to 12. Still no pinging. Maybe I'll try 14.
Speaking of carbs, I read of an air valve modification on page 54 of Jim Hand's book How to Build Max-Performance Pontiac V-8s. In a nutshell, the mod involves reducing the size of the notches in the front of the secondary flappers of early quadrajets for more air velocity over the accelerating-well ports, those little holes in the front of the top of the secondary openings. I was skeptical about it, so I did the modification with a couple of pieces of masking tape. To my surprise, this mod made a tremendous improvement in the low end throttle response of the car. I have swapped out the large grooved flappers with a pair of later ones with the Jim Hand modification for a permanent installation.
My question is, since a few later carbs I have also have those little holes in them but no notches at all, would it help to add small notches in the air valve flappers in a later carb?
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