Weight of A/FX vs B/FX Pontiac Super Duty 421s
 

I am trying to make sense lately of the 1960s NHRA classes.
Have a math question about the 1963 FX class.
Rule book says:
A/FX = Cars lighter than 9.00 lb/CID
B/FX = Cars heavier than 9.00 lb/CID

Looking at the 1963 Pontiacs, all with 421 Super Duty's.
Weights are given as:
PM = Pete McCarthy, Pontiac Muscle Car Performance
DRFS = Larry Davis, Drag Racing the Family Sedan
3300 lb Swiss Cheese Catalina PM pg 153
3300 lb Swiss Cheese Cat DRFS pg65

Now, 3300 / 421 = 7.84 (way less than 9.00) so how did the Swiss Cheese Cats run in B/FX and not A/FX?

A weight of 3790 / 421 = 9.00 seems like the minimum to get into B/FX.

There is a note saying (PM pg156) the Howard Maseles / Packer Pontiac Swiss Cheese Cat ran 117mph in A/FX at the US Nationals in 1963. But, usually, all the Swiss Cheese Cats are said to have run in B/FX.
How could they be this light (7.84 lb/CID) and still be allowed in B/FX ????

DRFS pg66 says the 421 Tempests came in at

3200 / 421 = 7.60 Tempest 421 coupe, ran in A/FX
3450 / 421 = 8.19 Tempest 421 wagon, ran in A/FX
These line up with the NHRA Rule Book cutoff; they are under 9.00 lb/CID so run in A/FX.

The Swiss Cheese Cat does not line up.
Did they ballast the big Cat back up to 3790lb (so 3790/421=9.00) to run in B/FX ? If so then wasn't the Swiss Cheese a waste of time?
What am I missing?
(I was a little young to remember back then)

Re: Weight of A/FX vs B/FX Pontiac Super Duty 421s
 

I have a rule book from that era but it's on a broken computer. I found this article on the Swiss Cheese if it helps at all:

http://www.supercars.net/cars/4922.html

http://blog.hemmings.com/index.php/2...ll-for-800000/

Dale

Re: Weight of A/FX vs B/FX Pontiac Super Duty 421s
 

Dale,
Thanks, I had seen 1 of those links but not the other.


Recently some of us were resolving another issue, about Grumpy's Toy, and after much searching found that Chevy454 over on HAMB went to a huge amount of work and scanned all the NHRA Rule Books into PDF. VERY handy!
1958-1968 NHRA Rule Books scanned into handy PDFs

http://www.jalopyjournal.com/forum/threads/nhra-rule-books-1958-present.870742/

The links you gave bring up yet MORE confusion!
They both say the big Packer Pontiac set the C/S record in 1963 at 12.27 and 114.6.


Well, to run C/S, as I read the Rule Book, at 10.60 lb/hp minimum, a 405hp car would have to weigh at least 4300lb (or 4350 at the 410hp rating).


So the car weighed 3300 yet ran in B/FX (well maybe) and now we read it ran in C/S meaning it had to weigh 4300 or more??


I also don't see how NHRA would even let the car into C/S as there were only 14 swiss cheese cars made, and less than 100 SuperDuty cars made near as I can count for 1963.
EDIT: I have seen where these cars ran in A/S, in AHRA not NHRA. AHRA did not require 100 units production like NHRA.
Maybe that 12.27 at 114.6 is the A/S record in AHRA, not the C/S record in NHRA.
If the Cat was "de-lightened" say in the rear half only, brought up to 3580 lb, it could run in A/S with a weight break of 8.70 lb/hp (assuming AHRA weight breaks are same!)
If it were de-lightened even more, up to 3790lb, it could run in B/FX at a weight break of 9.00 lb/CID.
De-lightening would make the Swiss Cheese Cats tail-heavy, great traction like a wagon.

Beautiful big cars, would be nice to make sense of their NHRA history.