1973 454/245 update

[Chipper Chapman]

https://nhraracer.com/content/genera...080&zoneid=132

Says updated to add cylinder head castings, but no change when you look at specs. Anyone know what?s changed? I assume the 241 is being added

[Adger Smith]

added 60447 and 12363391 alum heads to SS 245HP??? they are highlighted in yellow

[Dwight Southerland]

Originally Posted by Adger Smith

added 60447 and 12363391 alum heads to SS 245HP??? they are highlighted in yellow

Where do you see that, Adger?

[Adger Smith]

Woops,
Thanks Dwight. I Must have gone off in space...Looks like it is updated in 2 places.. && for Superstock and SS GT
From NHRA Technical Specifications
For
1973 Chevrolet Motors
Try this:
72 140 329686
85 140 329686
100 250 331183
115 307 3998993,333881,333882,3973493
145 350 333881,333882,3876487,3973487,3998993,3973493,3998 997
150 400 333881,333882,3876487,3973487,3998993,3973493,3998 997
175 350 333881,333882,3876487,3973487,3998993,3973493,3998 997
190 350 333881,333882,3876487,3973487,3998993,3973493,3998 997
215 454 353049,6272292
245 350 333881,333882,3876487,3973487,3998993,3973493,3998 997,330545
245 454 353049,6272292 245 454 353049,6272292
250 350 333881,333882,3876487,3973487,3998993,3973493,3998 997,330545

[Adger Smith]

CHEVROLET - 1973

250 250 350 350 400 400 350 350 454 454 454 454
* ** * ** * ** * ** * ** * **
Manual Only Manual Only Auto Only Auto Only Auto Only Auto Only Auto Only Auto Only Auto Only Auto Only Auto Only Auto Only
&-$-% &-$-% $$ &-$-% &-$-% &-$-% && &&

100hp 100hp 145hp 145hp 150hp 150hp 175hp 175hp 215hp 215hp 245hp 245hp

BEL AIR 121.5
Sedan 4 Dr 26.95 26.95 18.07 18.07 15.11 14.33 11.89 11.89

IMPALA 121.5
Sedan 4 Dr(Sport) 18.15 18.15 15.17 14.39 12.05 12.05
Coupe 2 Dr (Coupe) 17.92 17.92 16.93 16.93 14.99 14.21 11.90 11.90
Coupe 2 Dr (Sport) 17.86 17.86 14.93 14.16 11.86 11.86
Sedan 4 Dr 18.04 18.04 15.09 14.31 11.98 11.98

CAPRICE CLASSIC 121.5
Sedan 4 Dr (Sport) 16.88 16.88 12.14 12.14
Coupe 2 Dr (Custom) 16.61 16.61 11.96 11.96
Convertible 16.81 16.81 12.09 12.09
Sedan 4 Dr 16.75 16.75 12.05 12.05

STATION WAGONS 125
Bel Air 4 Dr 2S 20.61 20.61 18.96 18.96 13.58 13.58
Bel Air 4 Dr 3S 20.84 20.84 19.18 19.18 13.71 13.71
Impala 4 Dr 2S 20.71 20.71 19.06 19.06 13.65 13.65
Impala 4 Dr 3S 20.99 20.99 19.32 19.32 13.82 13.82
Caprice Estate 4 Dr 2S 19.28 19.28 13.78 13.78
Caprice Estate 4 Dr 3S 19.52 19.52 13.95 13.95

S/SS Factors 145 145 230 230 250 250 275 290 365 365 365 365
12.18.02 12.18.02 1.1.10 1.1.10 7.31.02 5.30.02 7.31.02 7.31.02
S/SS FACTORS w Replacement Heads 235 235 255 260 280 300 375 375
1.1.18 1.1.18 1.1.18 1.1.18 1.1.18 1.1.18 3.20.14 3.20.14








% = RHS Cast Iron heads # 12400 & 12402 accepted as replacement head
$ = Edelbrock heads # 60887, 60637 accepted as replacement head
$ = Dart Cast Iron heads with cast # 10021070, 100220010 accepted as replacement head
& = World Products Cast Iron heads with cast #'s 043600 & 043610 accepted as replacement heads
&& = Edelbrock 60447,GM 12363391
$$ = RHS 12400, World 043600


* = Stock Factor
** = Super Stock Factor

[Dwight Southerland]

Adger,
I keep a pretty good history of changes to the class guide and the blueprint specs since I started my website to be able to track changes over time. The Edelbrock heads and the the 391 GM aluminum head were added to the class guide in 2021, so that's not new. The 049 and 292 GM heads are in the 2006 blueprint specs, so that's not new. Not sure what NHRA's announcement is about unless they have not accurately published the change they are referring to (which is not new either!).