Ol' Fart's Firebird Fantasy

oldskool · 01-17-2015, 09:53 PM

Again, the main reason for exploring the '76 455 possibilities, is because I already have a running 455 with 6x heads, in my '68 bracket Bird. I can get it running good in the bird and see if it has the potential to run the index in a heavier '76 body.

At 3664lbs, the TA is the lightest body I could run. That's an 11.82 weight break. If I understand the rules correctly, you can add weight to make the next lower class, or take out weight to fit the class better. So, to fit the 11.50 weight break perfectly, that would be 11.5 x 310 = 3565lbs.

http://www.classracerinfo.com/Engine...px?ENGINE=2107

That would run H/SA, which has a 12.15 index. Some of you guys who know how to figure all this, please check my calculations and see if I am correct.

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

I think my 455 will run at least mid 11's in the '68 Bird. I haven't weighed it, but it should weight just over 3000lbs. So, if I put it in a '76 Bird which weighs 3565, that should slow it down by about .57 sec. So, if the motor runs an 11.50 in the 3000lb Bird, then it should run between 12.00 and 12.10 in the heavier '76 TA, with the same trans, converter and rear gears.

Now I'm not use to figuring out all this stuff. We just ran a '68 Bird at 3300lbs with a 330 hp engine and it came up exactly 10.00. So some of you guys who know how to figure all this out, please check my calculations and see if I'm anywhere in the ball park. Thanks !

Kegracing · 01-17-2015, 10:27 PM

Oldskool,
I will be watching this with interest.
One thing to remember on the weight calculations, you have to add 170 lbs for the driver to the weight. So your 310 hp times 11.5 weight break = 3565 + 170 = 3735 lbs race weight.

I have a 67 Firebird Convertible that I run in IHRA stock, with a zz4 crate motor (G/CM). I also bracket race it. More brackets than anything last year and probably this year, as I have a son who just started Jr. Dragster racing.
Would love to build a 400 - 4 speed combo eventually, and I have a set of 670 heads and intake - 1967 only combo on the 400. But time, work, kids, money, etc. all have this on hold. My car is originally a Sprint OHC 6 car, and I have the original motor in the shed.
Good luck with your build.
There are some really knowledgeable Pontiac people on here that are always helpful. If you ask nice, sure you will get all the help you need.

Ken

Stock 412

01-17-2015, 09:53 PM	#1
oldskool VIP Member Join Date: Dec 2014 Location: The Land of Bayous, Boudin & Crawfish Posts: 1,668 Likes: 223 Liked 747 Times in 362 Posts	Re: Ol' Fart's Firebird Fantasy Again, the main reason for exploring the '76 455 possibilities, is because I already have a running 455 with 6x heads, in my '68 bracket Bird. I can get it running good in the bird and see if it has the potential to run the index in a heavier '76 body. At 3664lbs, the TA is the lightest body I could run. That's an 11.82 weight break. If I understand the rules correctly, you can add weight to make the next lower class, or take out weight to fit the class better. So, to fit the 11.50 weight break perfectly, that would be 11.5 x 310 = 3565lbs. http://www.classracerinfo.com/Engine...px?ENGINE=2107 That would run H/SA, which has a 12.15 index. Some of you guys who know how to figure all this, please check my calculations and see if I am correct. http://www.classracerinfo.com/NHRA_Classes.aspx I think my 455 will run at least mid 11's in the '68 Bird. I haven't weighed it, but it should weight just over 3000lbs. So, if I put it in a '76 Bird which weighs 3565, that should slow it down by about .57 sec. So, if the motor runs an 11.50 in the 3000lb Bird, then it should run between 12.00 and 12.10 in the heavier '76 TA, with the same trans, converter and rear gears. Now I'm not use to figuring out all this stuff. We just ran a '68 Bird at 3300lbs with a 330 hp engine and it came up exactly 10.00. So some of you guys who know how to figure all this out, please check my calculations and see if I'm anywhere in the ball park. Thanks ! Last edited by oldskool; 01-17-2015 at 09:56 PM.

01-17-2015, 10:27 PM	#2
Kegracing Member Join Date: Jun 2002 Location: Red Oak, TX Posts: 441 Likes: 0 Liked 0 Times in 0 Posts	Re: Ol' Fart's Firebird Fantasy Oldskool, I will be watching this with interest. One thing to remember on the weight calculations, you have to add 170 lbs for the driver to the weight. So your 310 hp times 11.5 weight break = 3565 + 170 = 3735 lbs race weight. I have a 67 Firebird Convertible that I run in IHRA stock, with a zz4 crate motor (G/CM). I also bracket race it. More brackets than anything last year and probably this year, as I have a son who just started Jr. Dragster racing. Would love to build a 400 - 4 speed combo eventually, and I have a set of 670 heads and intake - 1967 only combo on the 400. But time, work, kids, money, etc. all have this on hold. My car is originally a Sprint OHC 6 car, and I have the original motor in the shed. Good luck with your build. There are some really knowledgeable Pontiac people on here that are always helpful. If you ask nice, sure you will get all the help you need. Ken Stock 412