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Discussion Starter · #1 · (Edited)
time to swap. i hope a 4bt will work better than the small block. what do you guys think. currently it is tbi 350 700r4 and dual cases. heres a couple pick before i start.
 

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The 4bt vs the 350 ,the power band of the cummins will be lower than the 350 and with your gearing it might be to low.

The RPM will also be lower on the 4bt as well .


CrewCab59
 

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Discussion Starter · #4 ·
i wouldn't mind having more power in the lower rpms.
 

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Reminds me of Marks Ol toy from WMS......looks good. I dam neer killed myself rolling the 52s arround, and the 49s wasnt that much fun either. I am still on the edge on weither to swap out the 302 for the 4bt in my buggy. I just dont think I will be happy with the get up and go because of the gearing, but I also run/jump alot at the dunes. What kind of wheelin are you mostly into? Flat/big rocks....rocky hillclimbs etc?
 

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Discussion Starter · #7 ·
mostly rock crawling. trail riding. not a whole lot of wide open driven.
i think i could use the torque.
 

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Discussion Starter · #8 ·
Can you post more info on the TOY ( spec's ) ?
toy body and frame. 350, 700r4, 203 205 cases, rockwells, four link front and rear. fox air shocks in back, coils in front. tube front clip with exocage, rear steer.
 

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sounds like it would be a good swap for you then. I am worried about needing to get some wheel speed up and going, and only having half the rpm before having to shift. There have been quite a few times where im bangin the rev limeter at 6500 back and forth to make it up something. For true crawling though it will definatly be a torque monster, that would just lug its way through, or spin the tires, or break something if it got in a bind with that low of a ratio.....torque is a mother ;) One thing to think about.. everybody will love it at camp, but after a couple of hours on the trail they might be wanting some ear plugs, and a rag to wipe the soot off of there windsheilds :grinpimp: nice to have ya here...later
 

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Discussion Starter · #10 ·
it will have a cool factor thats for sure. i will keep the small block just in case i want to go back.
 

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Do a lot of mudding? I dont think you're gonna get good wheel speed with a diesel. If you're in to mainly rocks, the 4BT should be fine.
 

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Discussion Starter · #13 ·
made them myself. used 20" split rim wheels welded centers in.

no mudding
 

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The 4BT would be great for the rocks then. You've got some awesome gear reduction - not sure on your doubler but I'll assume 4:1 x 3.06 1st gear x 6.72 in the rockwells. 82.2528 crawl ratio. Add that to torque converter multiplication and you've got some massive torque. 4BT would rock for crawling compared to the 350. You've got an enclosed fuel injection system too on the 4BT which will help in the rocks. Not sure how wild you get but have you considered running a dry-sump system?
 

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your rpm/speed looks like it would probably work pretty well. Especially with a 3200rpm governor spring...
 

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What gear ratios are in the axles and in the t-cases? What specifically are you not happy with the 350 about, or should I say what do you expect to get from the 4bt that the 350 can't give you.
BTW Nice truggy! :beer:
 

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Discussion Starter · #17 ·
dual cases. 4.1. 6.72 gears. looking for the low end.
 
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