NHRA rulebooks: '69 or earlier

[Chevy454]

Anyone have any old NHRA rulebooks? I've got '70-72, but am curious as to if '69 and earlier are pretty much the same. I'm betting they are, but just "curious". The part I'm interested in is the wording on the exhaust:

EXHAUST SYSTEM: Exhaust system must be equal to factory equipment per h.p. claimed. Dual exhaust pipes, with mufflers, are permitted. Headers are also accepted, but exhaust must be production type routed through mufflers and tail pipes. All mufflers must be production type and installed in the stock location - may be moved forward if original location was located behind rear axle - with tail pipes extending at least to the rear axle. The main body of any replacement muffler must be at least 18 inches in length. Open bypasses may be used, but mest be installed in front of the muffler and in such manner as to direct exhaust away from the strip, tires, and car body.

That's verbatim from the 3 ('70, '71, '72) book that I have...was it the same in '69? '68?

Thanks!

[Verne_Frantz]

Rob,
I have NHRA rule books all the way back to 1959. If you're specifically interested in the exhaust wording from the '68 & '69 book, I can check them tonight and let you know tomorrow. Unless someone else pipes up today.
Verne.

[JoeC]

I know that rule changed at some point because in the old pics you see some cars with tiny mufflers and pipes that were hung on the car just to meet the rules. They were small light parts and were not connected to the headers as the rules allowed open headers. Then at some point they changed the rule to where you had to have more of a stock looking ex system.

[Verne_Frantz]

Rob,
What class are you interested in.........? I'm guessing Stock, since Pure Stock doesn't allow headers, and Super Stock didn't require a full exhaust system.
Verne.

[Chevy454]

Yeah, stock is what I'm after. Just curious when, and how long, the exhaust rule was in effect.

[Verne_Frantz]

Rob,
I looked back as far as my '65 book.
Results:
'69 had the exact same wording except for a 3 1/2" outlet size limit on the exhausts, rather than 4"
'68 the same. They also grouped stock and Super Stock under the same exhaust rules.
'67 Same as above
'66 Same as above
'65 Same as above

I didn't look back further, but I know in '63 you could still get away with any tiny muffler and pipe. The wording did not specify an exhaust as per the original horse power rating of the car. But from '65 up, it did.

Hope this is what you were looking for.

Verne.

[Belair62]

What did a Z-11 come from the factory with ? 63 SD Catalina swiss cheese came with a tiny single exhaust and those gorgeous exhaust manifolds with dumps.

[Chevy454]

Thanks Verne! Someone also emailed me off line and said that they rules almost identical until 1974.

[T Billigen]

I think the Z-11s came with a stock exhaust system with cast iron headers from the factory. They may have been a special cast iron header? /ubbthreads/images/graemlins/dunno.gif

[Chevy454]

Verne:

That helped a lot! One last question: was there a compression ratio rule? It's my understanding that currently you have to be under the advertised cr, but was it that way prior to '74?

[Verne_Frantz]

Rob,
I'll go back and check again. Computer at work - - - books at home.........

Belair,
The Z-11 did get delivered with the full stock exhaust, just as any other hi-perf 409 would have had. The cast iron manifolds were the std. 925-926 units. Nothing wild like Pontiac did!

Verne.

[Chevy454]

The Chevys were definitely lacking in the exhaust manifold department. Here's a couple of "cast headers" the competitors offered:

426 Hemi:
http://www.v8buick.com/attachment.php?s=&postid=56021

427 FoMoCo:
http://www.v8buick.com/attachment.php?s=&postid=217637

Wouldn't it be nice... /ubbthreads/images/graemlins/tongue.gif

[Verne_Frantz]

You know Rob, going back over these old rule books is bringing back memories and making me feel like an old drag racer again. Could be dangerous!

Anyway, I couldn't find any specific reference or rule regarding compression ratio. The only mention of it is under "pistons". Any aftermarket piston was allowed as long as it was based on the OEM design and no piston could be used that would increase compression ratio.
That rule is present from '65 - '69. There's another way it could be raised though.
'67-'69 rules permit up to a .030" overbore (on '63 and later engines) but with a maximum cubic inch size of 430ci in SS/A & SS/AA. (A .060" overbore was allowed on '62 and earlier engines with no maximum size specified). It also notes that the bore size would be measured above the ring travel, to allow for cylinder wear. So, we know that for Chevy V8s (except for the 348-409 W design) boring increases compression ratio. (swept volume increases, but combustion chamber volume remains the same).
One other possibility to raise the C.R. might be if the parts system listed thinner head gaskets. In general, the rule says all engine components must be of the type originally offered to the public (unless noted otherwise, as with the pistons).
For '65 & '66 the overbore rule was slightly different. Same as above, except the maximum size was 427.2ci. (!!) in S/S, S/SA, A/S, A/SA and FX classes.
So, there you go.........
Are we planning on getting serious with the 1320 here????

As for those cast iron manifolds, the '63 & '64 409 design actually did flow much better than the earlier ones, but not as well as those radical F--d or Pontiac units. I have a set of those on my '62, and can squeak by the critics since that design was offered as part of a service package in April '62. (it's a late April car).
I know your MKIV big blocks were choked pretty hard with the factory manifolds, and really wake up with a set of headers.

Regards,
Verne.

[Chevy454]

[ QUOTE ]
Are we planning on getting serious with the 1320 here????

[/ QUOTE ]

I wish! I would love to have a A/SA car to play with, but too many other projects, and too little time. There's not a chance in Hades I could be competitive, but yanking the wheels like they do has GOT to be good for something!

Mainly I'm just curious about how NHRA "used" to be. NHRA seems to be trying to phase out the sportsman guys as of late, so pretty soon all this "class" stuff is gonna be history...

[Belair62]

Here is the ugly end of an aluminum Pontiac SD exhaust manifold...cast collectors.

[Chevy454]

Are those dumps?! Way cool! Did they come from the factory with those on the ends of the manifolds?

[Belair62]

Yes those are factory dumps....manifolds came from factory either aluminum or cast iron..pretty exotic stuff....

[JoeG]

Very nice--- /ubbthreads/images/graemlins/beers.gif

[Belair62]

Probably should have kept that one.

[JoeG]

/ubbthreads/images/graemlins/shocked.gif----Gone????

[Belair62]

Yep..... /ubbthreads/images/graemlins/crazy.gif

[JoeG]

Keep the next one--------- /ubbthreads/images/graemlins/wink.gif

[JoeC]

Whooz your daddy 1963 427 BB MKII mystery motor had nice headers. After 63 most racing allowed tube headers so the cast headers became a lost art.

[Belair62]

Artwork !