[chrisp]

Originally Posted by Dick Boneske

The stock '66 center carb venturi's are 1.180" vs the earlier center carbs at 1.250". The '66 carb probably flows more air due to the larger airhorn and throttle plates. There are Rochester 2 barrel carbs that have the same 1.310" venturi's as the end carbs. Using a float bowl from one of those would make sense to me rather than ruin a "575" carb.

As I said, the end carbs' venturi's are at 1.310" stock. I've successfully opened them up to 1.44", using a sanding drum, beginning with #80 and finishing with #340 sandpaper. This is about the maximum you can enlarge the venturi's on the end carbs with out breaking out of the casting. Some use epoxy to go beyond what I've done. I see no need to use a cone-shaped tool, as the area below the venturi small diameter is tapered to the throttle plate size.

I can send pictures if you want, but they look just like stock end carbs with a .130" larger hole. I'd love to know how much this increases flow. As I've stated in previous posts, Dan Whitmore built a 455 engine for the '65 GTO ,Glory Days, with a modified '66 Tri-Power that ran very low 10's before he switched to a Dominator. This was in the 1980 time frame. I have the manifold he used that was extensively modified, but he only removed the air cleaner webs from the carbs, did not enlarge the venturi's.

The 59 to 66 tripower end carbs have a 1 3/8" venturi = 1.375" from the link posted , Is this info. wrong ?