[RARON455]

Hello, looking for some input on what I am considering this summer, I have a 69 bird with a solid roller 462, I have cal-tracs on the car and a 3.42 rear gear, I KNOW it is not a good gear for the track but I drive this car alot in town and on trips to my relatives, it has current tags and inspection and runs on premium, so it really is a street car. At the track I hit it with a 150 shot of spray, last year the best time I got with no tuning or adjusting on my first time out with the new solid roller cam was a 7.06 at 99mph with a 1.80 something 60 foot. I am running a 28 inch tall slick HERE IS MY QUESTION to compensate for the street gear I am wanting to swap to a smaller 26 inch tall tire instead of the 28 How much of a difference would you guess that would make on my ET. I know there are alot of experienced racers here so I would appreciate your input Thanks.


heres a pic, I sold my bike to get the T/A

[66bonne]

With the 28" tire your effective gear ratio is 3:19 as opposed to the 26" giving you the true 3:42. I have a 3:42 in my Catalina and recently tried a 28" tire and was not happy with the results. We lost about a tenth to .15 in the quarter. We immediatley went back to the 26" at the track but use the 28" for street driving. BTW, those are pretty impressive 1/8 track numbers you are posting, at a 1/8th track you need all the gear you have in that rear end.
Jim

[grandville455]

I would have to agree with Jim... I have gained about 2 tenths switching to the smaller tires.... But I also have the lower gear set in my tranny too...So that could have contributed to some of the gain too!.. But with the lower gear and smaller tire..my 1st gear effective ratio is 4.08!

[79TA455STROKED]

My times below were with a 26" tire and 3.42's.
I switched to a 3.73 but the car didnt want to hook anymore with the 3.73 and 26" tire.I lost about a tenth and it was in the first 60'.
Im now going to a 28" tire with the 3.73.It is very even to a 26" tire and 3.42 gear but ill have the benifit of the rollout fron the 28" tire rather then the 26".
If you already have the 28" tires,go to a 3.73 gear.Some like a 3.90 gear with the 28" tire too.

[455Dave]

I wouldn't change anything till you get more run time on the car and get it tuned. This will give you a good baseline to go by before swapping tires. If all you run is the 1/8 the 26 in tire will help but depending on your converter slip on the spray, you could run out of motor in the 1/4. I ran 3.90s on 28 inch tires with a 150 shot and the motor maxxed out at 126 mph in the quarter. I swapped to 3.50 gears and the last time out my 1/8 numbers are 6.884 at 100.92 with a 100 shot. The track prep wasn't the best, 60' was 1.577. I drive my car on the street and like the current setup.

Nice bird!

[RARON455]

thanks for the responses I appreciate them all, I forgot to put in that I have a turbo 400 and am running a PTC converter 3200 stall, with anti balloon plate in it, called them and that was what was recommended. I hope the car will hook well thats why I bought the cal-trac setup. And yes there are mainly 1/8 mile tracks around me the closest 1/4 track is in ennis, and for me to drive the bird there would probably cost me about 60 bucks in gas alone, not to mention I would be booted out after the first run because the car has no roll bar, they let me slide at the local track, My buddies, or maybe because it is always the only 1st gen bird there.
So would it be a safe bet the guess the tire change would net about 2/10ths in the et?

[Goathead]

Need answers, this site is a good site to start...

http://www.wallaceracing.com/Calculators.htm