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Author Topic:   need help from experts on gear ratio
brdhil
Dirt Full Roller

Total posts: 26
posted December 05, 2003 09:49 PM  
we run on a high banked 3/8. alot of guys run from a 241 to 273 rear end ratio. is this in the ball park?now for the hard one! if i run a powerglide in low what number ring&what number pinion would i need to get the 241 or 273 rear end ratio??please help!!!

racer17j
Dirt Forum Champ
Total posts: 5390
posted December 05, 2003 11:17 PM  
My guess is that for them to run those gears they are running a T350. With a powerglide on a 3/8 we run 3.42 - 3.73 for the metrics and 3:50 - 3.70 for the 9" Ford rears. But it also depends on how the track is measured. I would do some more asking to see what final drive they are running. We ran 2:41 and 2:56 with our T350 and that worked well also. The 2:56 being better for our setup and track. Hope that helps, good luck.

brdhil
Dirt Full Roller

Total posts: 26
posted December 06, 2003 12:41 PM  
the glide ratio is 1.76 in low and will be running 225 70 15 tire. is the glide better than th 350. and allthe guys thatrun the 241 or 273 rear rnd run th 350 in low..

racer17j
Dirt Forum Champ
Total posts: 5390
posted December 06, 2003 05:49 PM  
we run a d shaped 3/8 with long banked turns.. so will the 3.42 work good?? thanks so much for u guys help.

racer17j
Dirt Forum Champ
Total posts: 5390
posted December 06, 2003 08:10 PM  
Again, it depends on your engine and how many RPM you want to turn it, with long corners and short straights brings up another variable. I would star with 3:42 and if you need more go 3:73. Cheaper to replace the gears than it is the engine. Good luck and let us know how it works out.

PureStocker #1
Dirt Roller

Total posts: 5
posted December 10, 2003 08:35 PM  
I am new to this forum and have been noticing alot of guys runnin 6.0 and taller gears on a 3/8 mile medium and high bank tracks, with anywhere from 83" to 88" rollouts and only hitting around 6000 rpm. I race on a 3/8 mile medium bank track and a 3/8 mile high bank track. Depending on the season, weather and track conditions I run 5.13 to 5.42 final drives and run from 6000 to 6500 rpm on 83" rollout. I don't see why there is that much difference. My rules call for 360cu max, .287 max lobe lift, on groved IMCA pulloffs. Can anyone explain why?

racer17j
Dirt Forum Champ
Total posts: 5390
posted December 10, 2003 09:19 PM  
the type of track can effect that also the lenght of the striaghts around here we have all black dirt tracks most guys run 6.20-33 with 83-86 in roll and turn around 68-7000. your tranny set up can also effect it if your running light weight tranny stuff you can get more rpm out of her another factor is the weight of the car. we run imca hobby rules so we are limited to 360 with 9-1 compression and a 2 brl carb so we like to keep the engine wound up to keep momentum as much as possible

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