Ol' Fart's Firebird Fantasy

[oldskool]

Originally Posted by Mark Yacavone

>>>>>You just need a Bonneville 2 dr. to make N/SA.<<<<<<


Yes 2 dr. should be 8.5 ..Watch the wagons..They had a weird one..2 inches wider too.

I must be missing something here. If I'm reading this info correctly, it says that the weight break for N/SA is 14.5 lbs/hp, with an index of 13 flat.

http://www.classracerinfo.com/NHRA_Classes.aspx

This page says a wagon hits 14.50 right on the head, @ 4103 lbs. But I got out the calculator and it says that in order to get those figures, they'd have to be using the 283hp factor for this engine in a Bird.

http://www.classracerinfo.com/Engine...spx?ENGINE=764

But the info on this page clearly says that the 180hp 400 engine was only factored at 283 in the Birds. It is factored at only 260 in everything else. So if this ain't so, now I'm really confused.

http://www.classracerinfo.com/Engine...spx?ENGINE=764

So am I just reading the info sheet wrong ? Or, are their calculations wrong ? Shouldn't they be using the 260hp factor for this engine in the Cats, Bonnies and wagons ??? If this info is incorrect, where exactly can I find the correct Stocker info ???

OK, assuming that the hp factor of 260 is correct, Then a 2-door Bonnie Brougham with this engine would have a weight factor of :

3689 lbs / 260hp = 14.19 instead of the 13.04 listed on the Class Racer Info page. So if this is correct, then you could just add weight to make the 14.50 lbs/hp break, which will be an N/SA.

14.50 x 260hp = 3770lbs - 3689 = 81lbs difference

So, you'd need to add 81 lbs to the shipping weight of the car to make the 14.50 weight break.

So. exactly how would I go about finding out if the hp factor is listed wrong on the sheet, or the calculations are done wrong, by using the 283 Bird hp factor for the engine ?

It would be a shame to build a car, going by incorrect info, only to find out at your 1st event tech, that you will be in a completely different class than you planned and built for.

[oldskool]

OK, unless and until I hear different, I'll assume that the 260hp factor is the figure to use when doing class calculations for everything except a Bird in '77. And, as of now, I'll have to use the shipping weights listed on these Class Racer info sheets. But I'll ignore their weight break calculations and do my own with a calculator.

So, by using this method, it appears that the highest class that could be run with this engine in a non-Bird is with a Cat 2-door.

3601 lbs / 260hp = 13.85

So, if I understand the rules correctly you can take out weight to meet the minimum for the class your car naturally falls into. Or you can take out more weight to meet the minimum for the next higher class. Or you can add weight to make the next lower class. So, that means that most cars can run any one of 3 classes just by adding or removing weight. Is this correct ?

If so, then the 2-door Cat I mentioned will naturally fall into the 13.50 weight break class, which is L/SA. Or, I can remove weight to meet the minimum for the next higher class which has a 13.00 weight break. This will be a K/SA with an index of 12.65.

13.00 x 260hp = 3380 lbs

3601 - 3380 = 221 lbs

If my calculations are correct, you'd have to remove 221 lbs from the 3601 lb shipping weight, to fit the 13.00 lb/hp weight break perfectly. Is it legal to run that far below the shipping weight ?

Just out of curiosity, what year did NHRA start allowing you to add and take out weight to make different classes. Before they did this, did they 1st just allow you to remove weight to meet the minimum for your natural class ? Or did they make the changes all at the same time ?

When we ran Stock, the car ran at no less than its shipping weight--period. What ever class it naturally fell into, that's the class you ran with that car. That gave some cars a weight advantage. We ran a 330hp '68 Bird with a 3300 lb shipping weight. So it was a perfect fit for the 10 lb/hp weight break--E/SA.

[Mark Yacavone]

http://www.classracerinfo.com/CGPage...7&MAKE=Pontiac

Dwight's site is not incorrect.
It's the operator that's incorrect. LOL

Just look up the body style, one at a time..You are confusing yourself the way you are doing it.

[oldskool]

Originally Posted by Mark Yacavone

http://www.classracerinfo.com/CGPage...7&MAKE=Pontiac

Dwight's site is not incorrect.
It's the operator that's incorrect. LOL

Just look up the body style, one at a time..You are confusing yourself the way you are doing it.

OK, thanks for the info. I've never seen that page. Don't know yet how to call it up. But I don't understand why the non-birds are shown with calculations using the 260hp factor on this page that you linked, and the 283 factor on the page I was looking at ? It just appears to me that it is not possible for both pages to be correct. Seems it has to be one way or the other ? But then, what do I know ?

[Danny Ashley]

Go to the top of this page and click on NHRA Competition. Then click Stock car classification on the left of the page. Then find the make and year and open it up.

[oldskool]

Originally Posted by Danny Ashley

Go to the top of this page and click on NHRA Competition. Then click Stock car classification on the left of the page. Then find the make and year and open it up.

OK, THANKS !

It takes longer to get there, but it does show the 260hp factor for non-Birds, AND shows the correct calculations for them. So, I need to depend on this NHRA site for all final calculations--Got it ! Thanks again !

[oldskool]

OK guys, I still need an answer to the weight change questions. When we raced Stock, you were stuck with whatever your factory shipping weight was. That was your min weight. So please tell me EXACTLY how the weight and class changes work. THANKS !

(1) Can you add weight to make the next lower class ?

(2) Can you remove weight to meet the minimum weight for your natural class ?

(3) Can you remove enuff weight to meet the minimum weight for the next higher class ?

(4) Is there a max amount of weight you can remove below your shipping weight ?

(5) Explain EXACTLY how the driver weight figures in again. Maybe I'll get it all, this time.

[impstocker]

OK I want to throw my .02 in. Earlier in the thread you were considering a "big Body" like 1976 Pontiac, I guess this would be a GM B Body car (1971-1976) I have never been underneath one but I did some research looking for diagrams or photos of rear suspension but came up empty. I did come across aftermarket parts though for these cars which include Control arms which tells me they are coil spring cars not much different than the 65-70 B Body gm car like my Impala.

If I am wrong here then skip the rest.

These are different from A Body cars which some guys have been showing you for rear suspension upgrades. The first difference is the coil springs perch between the lower control arm and frame, not on axle tube like A Body rears. The upper control ares are a straight forward shot, not angled like A Body cars. Some early B Bodies like my 65 came as a "3 link" rear suspension, 2 lowers only 1 upper bar. Hi-Performance did have 4 links like I have in the 65 Impala stocker I am building. No-Hop bars are not available for these cars .I have Southside Machine lower control arm traction bar which is basically a Square tube solid bushing bar with a adjustment that lowers the attachment point on the axle effectively changing the instant center of the car which aids in planting tires. The same effect is done with the "No-Hop" bars on the A Body cars. With adjustable Upper control arms, no air bags thats all I needed to do. Not really complicated. The only heads-up is where the upper bars attach to the crossmember on frame needs to be strengthen. I would leave at 6300+ RPM with a stick at 4095 lbs. Check out my Build in this forum,
"BBC Impala update" or something like that.

I would crawl under the cars to take pics but lots of snow , blizzard outside now!

Will Lamprecht I/SA Implala in progress.

[impstocker]

OK, this might be "blasphemy" even though the pics of the Wood's "Ton's O Fun" station wagon looks as cool as crap, I would say the suspension is not set up right and wasted motion produces wasted horsepower = lower ET's ? I liked the fact my Impala launched straight and level. Aren't we looking for that?

Will Lamprecht I/SA 65 Impala in progress

[Mark Yacavone]

Originally Posted by oldskool

OK, thanks for the info. I've never seen that page. Don't know yet how to call it up. But I don't understand why the non-birds are shown with calculations using the 260hp factor on this page that you linked, and the 283 factor on the page I was looking at ? It just appears to me that it is not possible for both pages to be correct. Seems it has to be one way or the other ? But then, what do I know ?

Dwight 's site makes this all much easier, but you've got to know where you're driving to first, other wise you'll crash and burn.
Start with NHRA and when you figure out where you're driving to, go to Dwight's deal.
It's the way to go..Trust me.