NHRA Street Classes During Late 60ties early 70ties

[69NovaYenko]

In the day I recall guys had a back and forth to work, grocery getting, take your girl to the movies daily driver. But come Saturday & Sunday they would be tearing up the asphalt at the local drag strip. Can anyone with a better memory than mine recall what NHRA classes these street legal daily drivers may have ran in during the late 60ties & early 70ties. I want to replicate the correct class letters/numbers on the windshield of the car I`m currently building.

[Straightliner59]

By the '70s, most of them were just bracket racers. Go to make a couple of dial-in passes set your ET, and don't go too quick. Mostly, they would just say something like "ET 13.27", or something like that. In the '60s, I think they may have been classified, somehow by the sanctioning body at hand.

[bamadon]

Take a look in the WIP Drag Racing section. The NHRA Rule Books for 1958 thru 1968 are available there.

[1972coronet]

Modified Production comes to mind.

[TarheelRick]

My '65 Chevelle 283/3spd car ran P/S in the late 60's.  If I had made minor modifications to the engine, it would have been Modified Production.  If I had gone further and done wilder mods to the engine, I could have been bumped up to Gas class. But as Bamadon suggests try to find a NHRA rulebook for the time period in which you are interested. Another suggestion would be to acquire some of the drag racing books available on Amazon - "Racing the Family Sedan" would be a good start. 

[TransAmMike]

The only car I actually street raced and drag raced (LaPlace Dragway in Louisiana and Gulfport Dragstrip in Mississippi) was my '66-325HP/4-speed Chevelle SS. Ran in D/Stock if I recall. A stock car could run headers and stiill be classed in the stock class.  I too think any other mods would be a Modified Production car...or Gas.

 

[Straightliner59]

10 hours ago, TransAmMike said:

The only car I actually street raced and drag raced (LaPlace Dragway in Louisiana and Gulfport Dragstrip in Mississippi) was my '66-325HP/4-speed Chevelle SS. Ran in D/Stock if I recall. A stock car could run headers and stiill be classed in the stock class.  I too think any other mods would be a Modified Production car...or Gas.

 

You are correct, sir! Stock class racers have been allowed to run headers probably since the beginning. The '59 Rule Book says they're fine, but, the exhaust must actually run through the mufflers and tailpipes. Even as late as '75, Stock Class cars could be no older than ten years. After that, you'd have to run SS. I found all this stuff out, when I was building my '63 Chevy II wagon SS/RA! Also, you're right about MP; compared to Stock and SS, MP was the wild west! I would say that, for the most part, by the mid-'70s, class racers were dedicated race cars, and generally weren't being driven to the track. That was a very interesting period for drag racing!

[BubbaBrown]

NHRA had their own ideas of what the horsepower was. Your engine might be factory rated 275 h.p. but the NHRA felt it was 325 h.p. That's what they used to factor. NHRA stock class was weight divided by horsepower, other sanctioning bodies might have used cubic inches into weight.

 

[Reegs]

The NHRA knew that advertised HP was just for the insurance companies, so they came up with a more accurate chart. 

The NHRA was weight divided by HP. The AHRA went even deeper - called "Formulas", they factored in cam,  lifters, two or four bbl, upholstery; all kinds of arcane sub-divisions.  

"Stock" was more-or-less based on what was offered in the showroom. No trips to the parts counter, no aftermarket goodies. That would have (should have) put you into the wild and wooly Modified Production class.

"Stock" more often than not was a matter of opinion.

Edited June 24, 2022 by Reegs

[Straightliner59]

Here's the link to NHRA's Stock Car Classification Guide. It's used for Stock and SS. If it works:

https://www.nhraracer.com/content/general.asp?articleid=46635&zoneid=132

[Dave G.]

I set my 390 Mustang up to basically meet Stock requirements. But my slicks were 11" wide and so they wanted me to go into SS. I would have gotten slaughtered there so ran brackets ( this was 1974). It's funny, those were a certain Hoosier slick and open headers blew them out unless they were practically flat. Open headers also scavanged the carburetor dry and I had to jet up several steps which in turn led to a higher volume fuel pump and cool can. Anyway, So a guy lent me a Super Stock M&H set of slicks only 9" wide and they hooked up solid. Then this small block Chevy racer wanted to buy my Hoosiers because He said he had some before and they hooked up just right with his I believe 327 Corvette in Super Stock so I sold them. But it's weird how the different combos work when you drag race and how the rules play out. But to me in my setup the biggest restriction to meet stock requirements was cam lift unless you got a special grind. At least so with the FE engine. So ditched the stock idea and upped my cam to a 600 lift bracket racing solid lifter cam and just stayed in brackets. By this time the car was not on the street.

I only ever trailered my car even when it was still registered.

Modified Production ( for that day/era/time period) was nuts but some cars in that class were actually street driven. At my track in NH you were more likely to see a registered MP car than SS.  Yet MP was faster back then and more radical. I think it's just SS was a pro class, you would see the factory sponsored cars there. If I could have run B SS I might have tried it but they tried to stick me in A with the 427's and hemis and stuff. Not sure what modeler can reap from my message but all I can say is been there done that and glad I did it.

[Daryl Romain]

Jr Stock was A/S (A stock) through about U/S for manual transmissions, A/SA (A stock automatic) through about N/SA for automatic transmissions, depending on HP to weight breaks. Automatic trans cars below N/SA ran with the manual cars. Jr. Stock ran 9 inch slicks maximum. Super Stock cars had higher power to weight ratios. Those classes ran SS/B though SS/F, with corresponding auto trans classes. They ran up to 12 inch sllcks, IIRC. If you changed your intake/carbs, and added a hood scoop, or used a same make motor that did not come in that body (454 Camaro) you were in Modified Production, A/MP through about F/MP. Fuel injection, fiberglass, straight axles, non matching motor brand (Olds in a Willys) put you in the Gas classes.

[Straightliner59]

4 hours ago, Daryl Romain said:

non matching motor brand (Olds in a Willys) put you in the Gas classes.

I enjoy discussions like this! That was MP legal in '75. The rules only state that the engine must be automotive. There's a thread, here:

 

[Daryl Romain]

I do distinctly remember, at one point, that NHRA Modified Production race cars had to have the same brand of motor as the body of the car. I could not tell you at what point that was.  By 1975, the popularity of the class was waning. Maybe the rules had changed by then. I can't remember any MP car having different make motor and body. I admit that I'm not an expert.

[Straightliner59]

5 minutes ago, Daryl Romain said:

I do distinctly remember, at one point, that NHRA Modified Production race cars had to have the same brand of motor as the body of the car. I could not tell you at what point that was.  By 1975, the popularity of the class was waning. Maybe the rules had changed by then. I can't remember any MP car having different make motor and body. I admit that I'm not an expert.

The only reason I know any of that, is because of projects I was working on! 😃 

[Mark]

Modified Production started declining in the early Seventies when some of the "off the pace" Pro Stock teams would make sufficient changes to drop into the Sportsman classes.  Prior to the tube frames and Lenco transmissions in Pro Stock, pretty much all that was needed was a switch to steel fenders, doors, and hood, and maybe a little more weight beyond that.

Throw in some of the Chrysler guys following factory orders when they didn't like the weight break given to wedge engine cars versus Hemi cars, and you end up with an invasion of big money into those classes.

The sanctioning bodies tried to create new classes like Super Modified and Econo Altered, but the big money guys moved in with high-buck engines and ex-Pro Stockers and took those classes over too.

[Daryl Romain]

I agree, and remember much of what you mentioned here. Especially the part about the factory sponsored MoPar teams 'bombing' the /MP and /Gas class records under factory orders.  I believe this photo was shot at the 1968 Winternationals in Pomona. Dick Landy put a scoop on the hood of his Hemi Charger, making it illegal for SS/D, forcing it into the A/MP class, which is what it says on the side window. I was 11 years old at the time, so my understanding wasn't all there yet.