cam selection/head flow

the opening may be big. but the hall to the doorway is almost a U-turn...  

Pontiacs are actually intake flow limited at higher valve lifts. They used 2.11" intake valves with 30 degree seats to produce great low lift flow. That's why they made superior torque over a broad range but flow stalled at over .450" or so. RAIV heads had taller intake ports and flowed better at high lifts. RAII heads used the standard intake port with the better flowing round exhaust ports. Both used the same 231/240 @. .050" cam, the IV had 1.65 rockers and 517" lift compared to 1.5 rockers & .470 for the II. A really good street cam in a 455. I've found it to be a bit soft in 400's until it's over 3000 RPM.

Nobody runs that stuff anymore since there are 4 different aluminum heads out that flow better than any factory head out of the box and WAY more when ported. I knew all this useless Pontiac knowledge would come handy some day.

imagechanger wrote: Pontiacs are actually intake flow limited at higher valve lifts. They used 2.11" intake valves with 30 degree seats to produce great low lift flow. That's why they made superior torque over a broad range but flow stalled at over .450" or so. RAIV heads had taller intake ports and flowed better at high lifts. RAII heads used the standard intake port with the better flowing round exhaust ports. Both used the same 231/240 @. .050" cam, the IV had 1.65 rockers and 517" lift compared to 1.5 rockers & .470 for the II. A really good street cam in a 455. I've found it to be a bit soft in 400's until it's over 3000 RPM. Nobody runs that stuff anymore since there are 4 different aluminum heads out that flow better than any factory head out of the box and WAY more when ported. I knew all this useless Pontiac knowledge would come handy some day.

Yeah, you played with those a little bit.... Have you had the old Girl out lately, Tom? Street nights are starting to get pretty good at Quaker. Have you been out there this year?

73 SD TA is one of my bucket list cars.

Have been to Thompson this year not Quaker though. They bounced me when I started going under 11.50 without a rollbar. Actually a guy I knocked out of eliminations protested me.

Have gone 11.0's at Thompson without getting hassled... Yet