Getting into the 12's

[fairlaniac]

Some of you may have rread my post on the "General Chat" forum about "First Time Jitters". At the ripe age of 48 I made my first strip passes. Why the hell did I wait so long? Needless to say I'm hooked. My best run was a 13.45 @ 105.41. This was on street BFG's 255/60/15. I know I need to step up to some slicks so that is part of the plan for next year. My BFG O.D. is 27.1 and I have a 3.70 rear gear. What would a 26 inch tire do for me? I know bigger is the cool look but I'm out to get some decent times and slowly get faster.

Thanks!

[Gameracing]

A shorter tire lowers overall gear ratio, which should help your ET, if your engine has the rpm capability, it might help you mph. A taller tire does have a larger contact patch though, Some cars need it.

[mike]

Some of you may have rread my post on the "General Chat" forum about "First Time Jitters". At the ripe age of 48 I made my first strip passes. Why the hell did I wait so long? Needless to say I'm hooked. My best run was a 13.45 @ 105.41. This was on street BFG's 255/60/15. I know I need to step up to some slicks so that is part of the plan for next year. My BFG O.D. is 27.1 and I have a 3.70 rear gear. What would a 26 inch tire do for me? I know bigger is the cool look but I'm out to get some decent times and slowly get faster.

Thanks!

We need the 60 to figure out what slicks will do. Nice pass and sweet car.

[fairlaniac]

My best 60 ft. was 2.039. See all four pass time slips here in .pdf format. Sorry it's sideways. I'm car 114 (circled).
http://www.fairlanet.com/images/timeslips_102908.pdf
Thanks for the compliment on the Fairlane.

[jays64II]

Changes I would make:

Mickey Thompson makes a drag radial in the 255/60/15. That is the tire I would use.

I'd see how it does then when you load the conv. to launch and see how much the 60' improves and see if the mph drops off. Your current mph is about a 12.80 pass. the conv. may need to be loosened up 2-3 hundred rpm. A lil more gear will help too like a 3.89 gear set. Right now you are only trapping about 4900 rpm so i'm thinking you aren't recovering enough at the gear changes and you are only in 3rd gear for a very short time before the traps. What RPM did you launch and shift at ?

[fairlaniac]

Changes I would make:

Mickey Thompson makes a drag radial in the 255/60/15. That is the tire I would use.

I'd see how it does then when you load the conv. to launch and see how much the 60' improves and see if the mph drops off. Your current mph is about a 12.80 pass. the conv. may need to be loosened up 2-3 hundred rpm. A lil more gear will help too like a 3.89 gear set. Right now you are only trapping about 4900 rpm so i'm thinking you aren't recovering enough at the gear changes and you are only in 3rd gear for a very short time before the traps. What RPM did you launch and shift at ?

Thanks for the tips.

My first pass was a disaster. I spun on launch and from first to second. I lowered the air to 21 psi on the BFG's and left at 1800-2000 rpm the next three runs and it helped. I shifted at +/-6000 rpm from 1st to 2nd and 2nd to 3rd, 3rd to 4th was about 5800. I have a Ford Toploader 4 speed with these ratios 2.78, 1.93, 1.36 & 1.00. I shifted into 4th right around the 1000 ft. mark.

I have a set of 4.10 gears in the garage and was thinking of using them at some point? If I were to use those gears, which diameter of a tire would be suitable? My dyno numbers on the 390 are 458hp @ 5500, torque 471 @ 4450 all at the flywheel.

Thanks,

[jays64II]

Ooooppsss !!! Sorry about the torque converter comments from my previous post! Not many 4 spd guys left racing them but then again your car is more of a cruiser/fun toy/show car/just get out and have fun kinda car. With that being said you have a lot of variables to consider when racing with a stick.....way more variables than with an automatic but i'll assume ya already know what they are since i just now went back and read the whole post that you had posted in another section about "first time jitters".

5500 rpm is about average for a good running FE motor. Alotta weight to swing around ya know. Your poor 60' foot time was obviously a result of street tires and not being able to launch at a usable rpm to allow the motor to get into the "happy zone" quicker.

Honestly ... if you already have the 4.10 gear set and you can live with the added rpm while cruisin then go for it. Now tire size becomes a choice. Ya know the 255/60/15 fit fine and you should be able to fit a 275/60/15. Doing the math for perfect traction and conditions puts the 255/60/15 tire with the 4.10 gear and at 5500 rpm at about a 12.55 at 107.40 mph. That is if you can launch perfect , shift perfect and trap perfectly at 5500 rpm. I would think you would need a launch rpm of 3000 rpm to achieve these numbers. Now....all things staying the same and switching to the 275/60/15 tire will yield a 12.08 at 111.50 mph. Your Fairlane probably weighs...i dunno....3600 - 3700 with you in it? My dad had one back in the day and some good friends race and build FE motors so I know a few things about em.

So....in theory the math is there. You just gotta make the rest happen. My math has a 1 tenth and 1 mph clause !!!! LOL !!! I can usually get it within 1 tenth and/or 1 mph.

[fairlaniac]

Jay,
Thanks! You've provided me with a bunch of good info. The gears I have are actually some Richmond 4.11's for the 9 inch. The 4.10's were from a long gone 5.0 Mustang street car with a 8.8.

Thanks again!

[jays64II]

No problem Doug! I've always wanted a Fairlane like yours or a same year Comet. Good luck with it!

[adamsvega]

Jay forgot to tell ya that shifting perfect is based on rpm drop from each gear and will be different for each shift in a toploader . dont sweat it get used to the car first . find out how high you can leave with a good tire/psi combo first. 6k was a good guess to start shifting .
did you say you got 4.10's in the car or in the garage??? put em in if ya got em!!! a perfect slick launch should slip the tire 1.5-3 revalutions loaded up and folded 1.5-3 folds in the sidewalls moving outa da hole unless you got a adjustable clutch to do it for ya . thats the reason for white stripes and video repay!! when ya get it in that zone you got wiggle room for traction or rpm variation and it will run the same .