[John Langer]

a 420" Pontiac would have to weight the same as a sbc but you are limited to the edelbrock or wenzler head or anything under 477"??? You could not run a 420" motor or even a 440" Pontiac in that class with anything other then a 5-speed behind it because you would not be able to get to weight. Even if some long stretch of the imagination that you could get to weight, you would be something like 60% on the nose. Good luck making that work with a 10.5 tire.

 

[John Langer]

I am pretty sure that the NMCA Pro Stock late model BBC f-bodies can get down to around 3150 with all of the weigh out of them. I can get my car to around 3135 ish, no ballest and a 235lb driver. Keep in mind that a traditional Pontiac weighs around 100lbs or so heavier then a BBC. Additionally, I have an IA1 block in my car which is around 30-40lbs lighter then the IA2.

 

[John Langer]

a 400/420/440 pontiac would run at sb weights and then the pontiac weight break on top of that. The Tiger head is not legal on a sub 477" motor????? You would be stuck using the "E" head or Wenzler. Unfortunately the stock deck height on a Pontiac is in the neighborhood of 10.220". The "most" you can take off of an aftermarket block is .100. The BBC is 9.800 and can go to around 9.500 +/-. That is alot more block material for the Pontiac = weight. The lightest you will see a Pontiac crank is around 62lbs. There are sbc and sbf that are out there under 36lbs. The Tiger head with valves and springs (no shaft bars) weigh in at exactly 50lbs each.

 

[John Langer]

An aftermarket Pontiac block that is not filled is approximately 100-140lbs heavier then a stock pontiac block. The IA1 block is around 30-40 pounds lighter then an IA2 block. The IA2 added material in the valley area, deck, front of block and has registered mains. When they registered the mains, they simply added material to the pan rail of the block and then machined down the starter pad. The 303lb block, is that a tall deck or standard height block?

 

[John Langer]

There isn't any tall deck block running in either pro stock or x/s. I would go as far to say that I dont think there is 1 bbc with over a 9.600" deck height in pro stock or a bore smaller then 4.625. That is why the BBC is lighter then the Pontiac in those classes. My block weighs 260lbs bare and I have one of the "light" ones. You would think that you dropped a nut if you tried to put in the back of a truck by yourself.