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Author Topic:   1/4 mi gear/tire combo
rogracer2
Dirt Maniac

Total posts: 119
posted June 23, 2004 09:19 PM  
I'm running a 1/4 mile, medium banked, gumbo dirt track. I have a turbo 350 transmission, running in low, and in the rear I have 2.73 gears, using a combination of 255/60R15 and 275/60R15 tires, but I am being outdragged on restarts and coming off the corners. What size tire do I need to be using to get more pep on restarts and off the corners?

racer17j
Dirt Forum Champ
Total posts: 5390
posted June 24, 2004 03:34 PM  
So if I run the smaller tires on the back, that will give me more RPMs off the corners? Right now I have the smaller tires on the left, and the bigger tires on the right.


racer17j
Dirt Forum Champ
Total posts: 5390
posted June 25, 2004 06:20 PM  
i am new to dirt, however my best guess is
that the guys beating you on restarts have a rear gear that allows them to ''take off in first and then shift to second.i don't know what ratio the gears are in a 350 but it seems you are lacking sum..5000 seems like not enough again just a guess.good luck!!

te33
Dirt Freak

Total posts: 237
posted June 25, 2004 10:37 PM  
the gears are,2.52 in first,1.52 in second.you need to race it in 2nd,or high.that way you can kill them on the upshift on the restarts,you will have to be careful you will run over the guys shifting there standards.in second,a 410 gear will give you a final drive of 623,not quite enough.but usable,a 456 will give you a 693,a little much i think.these are the 2 'common' ratios for a 7.5 10 bolt.a 435 would be perfect,but i have never seen one.you need about a 666 final drive ratio.this gear however will not fit in a 7.5.i would strongly recomend a 9 inch ford,get a 666 and race it in high.good luck,are you running at screven?

racer17j
Dirt Forum Champ
Total posts: 5390
posted June 25, 2004 10:55 PM  
I'm running an 85 roll on the LR and a 90 on the RR - do you think that could be causing me to spin the rear tires off the corner? I do not have a tach in the car - but the motor sounds like it is turning high RPMs by the end of the straights.

racer17j
Dirt Forum Champ
Total posts: 5390
posted June 26, 2004 11:38 AM  
17j,i figured he was burning the tires off the corners,and a tick less gear with a little more zip on the restarts would be the ticket.15 guys ahead of you on the restart!come on don't be sandbagging,i know you run better than that.

J3
Dirt Maniac

Total posts: 188
posted June 28, 2004 08:46 PM  
Where do you get a memory tach for $100????

ryan
Dirt Forum Champ
Total posts: 776
posted June 28, 2004 09:11 PM  
Midwest Motorsports $109
AUM 233902

racer17j
Dirt Forum Champ
Total posts: 5390
posted June 29, 2004 06:42 PM  
I RUN A 1/4 AND 3/8 WITH A 355 ENGINE-TURBO 350 TRANS IN LOW AND TURN 5300 RPM 2.73 GEARS IN A 79 CUTLASS. REAR TIRE SIZE 215-65 15 LEFT FRONT 205-70-15 AND RIGHT FRONT 215-70-15. CAR WORKS GREAT TACKY OR DRY I HAVE TO ADMIT COULD USE MORE POWER ON TACKY, BUT ON DRY SLICK EVERYONE ELSE IS SPINNING THEIR TIRES OFF AND I CAN JUST DRIVE THE CAR RIGHT AROUND THE CORNERS WITHOUT GETTING LOOSE. HOPE THIS GIVES YOU MORE INFO TO GO ON.

DirtFreak08
Dirt Forum Racer

Total posts: 77
posted July 08, 2004 04:53 PM  
I ran a 350 turbo last season with stock rear end and 241 gears on a 1/4 mile track. Did decent on starts and gave good power down the straight. I put a stall converter in it at midseason to try to help on the starts. It helped out a little, but not as much as I wanted. I bought a new car for this season, it had a 9" ford geared to 620 and a powerglide tranny. This thing is a rocket on the starts and i'm hitting right at 6000 thru the straights. My stagger is 82 and 84. Handles like a dream. I can't run the low groove, my 350 is strong but can't pull the 400's off the corner.

mainshaft
Dirt Roller

Total posts: 9
posted July 08, 2004 08:16 PM  
I know a guy that runs a 360 chevy with a powergilde in first gear with a 3.90 gear and 26inch tall Hoosier tires at Memphis Motorsports Park which is a mid-bank gumbo 1/4 mile that 90percent of the time is dry slick and he gives up a hair in the corners but coming out he outpulls em all don't know what rpm he's turning but if he gets the lead watch out. His name is Terry Grey and he drives a 2nd gen camaro in the street stock class.

[This message has been edited by mainshaft (edited July 08, 2004).]

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