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What stall do I need?

trevmountain

trevmountain

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Truck is an 84 K30, T 400, 373 gears, 37" tires. I have a gear vendors I am in the process of bolting on as well. I have not run the vendors with the 373's and being that I have it now I am thinking about gearing to 411's or even 456's depending on how everything comes together.

I am having the 454 built right now. Nothing to crazy, I am going with a roller cam, edelbrock performer intake, 049 heads with some pocket work-bowl blending. Should come out at around 460 to 480 horse. My 400 tranny is stock but does have a heavy duty converter and shift kit. Just wondering if I need to go with a higher stall for any of the gearing combo's I am looking at.

Thanks
 
depends on your cruising rpm and good idle at what rpm. If you are too low it will die at idle and you don't want it so high the stall is near cruising rpms. IMHO. SO lets say you are doing 1800 rpms at 50mph cruising. I'd prob shoot for 12 to 1500rpm. I do not know what stock stall is. Just gives you an idea of what to think about.
 
I would keep the HD converter

You definitly need some lower gears, but the torque of the BBC will overcome some of the poor gearing. Id go 4.56, or maybe even lower.
 
I don't know what stock stall is either. I assume somewhere around 1800 or so? Is this a situation where I will need to drive the truck to figure out the best stall?
 
if u have 37s with an over-drive ur putting on,definitely regear to 4.56s...then,i would get a stock or close to stock stall. like rusty said. the BBC will have enough torque to get it going. also the 4.56s will help the engine rev up into the cams power curve when u want it too. gearing is a BIG part in how ur truck will drive/shift. when i had an auto,i got the smallest above stock stall i could find. i dont no the exact numbers but it was only like 300rpm over the stock stall and i have a big cam. and i loved it. i also have 38s and 5.13s. now with a 465 tranny (1:1 final drive) at 55mph, im at 2500 rpm. just a reference for u.
 
ya,its the OEM manual transmission option for old chevys,4 speed with no over drive,some call it a 3 speed with a creeper.
 
I have a K-20 with a fresh 350/TH-400/3.73 and 37" tires and its a total dog getting off the line, first gear will hit 56MPH at 5000RPM with these gears. It was okay with the stock torque converter, it felt responsive. but then I swapped in a 2000RPM stall converter (100$ on summit) to let the cam get into its power band and It lets me launch a little better off the line but cruising around any kind of incline, it just slips a little too much for my liking. But its because these gears are way too low for these tires.

3.73 gears with 37" tires gives the effective gear ratio of 3.02

Just for fun, I threw on some stock sized 30" tires just to see how it feels to have the proper gear ratio with my new engine and MAN, it runs like a raped ape! The higher stall TC makes for great launches and doesn't slip when cruising with the correct gear ratio. I would need to re-gear to 4.56 to get near to stock, or 4.88 to have better acceleration at the expense of high cruise RPM.

with 37" tires:
4.56 gears = effective ratio of 3.69
4.88 gears = effective ratio of 3.95

Im gonna go with 4.56's on mine since I don't have overdrive and have to drive this to the trails far far away.

But for you with overdrive, 4.88's would be perfect. Lucky bastid :D

You will be happy with a 2000rpm stall TC only IF you re-gear. Actual stall speed depends on load, horse power, gear ratio, tire size, and weight of the truck. For a BBC you wouldn't want to go higher than 2000 stall.
 
Trevor check this out http://www.grimmjeeper.com/gears.html

You can mess around with that forever and just enter a .78 on one of the t cases high range numbers to get your final rpm with gear vendors.

I for one think a motor as strong as yours will be needs nothing more than a good stock convertor, you aren't going to need any help getting off the line man

Even a specific towing converter would be nice ( they are a lower stall but slip much less at cruise speeds)
 
Great thanks eric, very helpful stuff. Hey have you ever torn into a 205 transfer case. If you wouldn't mind check out my post of 205 slip yoke conversion thread I just posted up.

Thanks
 
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