shortening the 354 spring???

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shortening the 354 spring???

Postby rattlebox93 » Thu Aug 12, 2010 11:40 am

what actually do i need to do to the "4200" or 354 spring im getting realy to asseemble the geartrain and pump ect and would like to shorten the spring
93 d350 extended cab dually, 5 speed, he351cw, industrial man ported, ported head, 60# springs, 6x16's, ballanced, coated slugs, lowerd comp, 354 spring, piston lp, 1/2 lines, con f, home made water in the works still not running but getting close
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Re: shortening the 354 spring???

Postby ahale2772 » Fri Aug 13, 2010 7:07 am

i cant see why ud want to shorten the 4200 spring, thems are some uncaharted waters if ur making power up there
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Re: shortening the 354 spring???

Postby BobS » Fri Aug 13, 2010 9:59 am

I know it's just me and my opinion but I can't for the life of me see any increase in engine longevity when you start spinning it at more than twice the RPM where it was designed for peak torque. I think Cummins tested brand new engines years ago for collateral damage RPM's and IIRC it was 5250 RPM's when they go boom! I had that bookmarked before but seem to have misplaced it after a computer crash episode...
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Re: shortening the 354 spring???

Postby oldestof11 » Fri Aug 13, 2010 12:20 pm

The 5250 rpms is a TDR myth.

Peak torque can be changed. ;)
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Re: shortening the 354 spring???

Postby BobS » Fri Aug 13, 2010 1:33 pm

oldestof11 wrote:The 5250 rpms is a TDR myth.

Peak torque can be changed. ;)

I thought I read it someplace else other than TDR because I don't vi$it that web$ite.

I know, I'd like to lower mine to 1500!
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Re: shortening the 354 spring???

Postby ellis93 » Fri Aug 13, 2010 1:46 pm

What is all this talk of peak torque can be changed. With what?
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: shortening the 354 spring???

Postby Richie O » Sat Aug 14, 2010 6:59 am

You do need to clip them so it will fit and work correctly. How much?? No idea. Me scared of those RPMs. :shock:
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Re: shortening the 354 spring???

Postby oldestof11 » Sat Aug 14, 2010 7:24 am

Ellis, things like timing, cam, turbo, compression, all effect where the peak torque is at.

Something as simple as changing the 18cm exhaust housing to a 12 will lower peak torque down a few hundred RPM's as the turbo lights quicker bringing the full boost to the engine sooner.
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Re: shortening the 354 spring???

Postby PToombs » Sat Aug 14, 2010 5:33 pm

And here I thought you were going to use an eraser and change the curve on the dyno chart. :oops:
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Re: shortening the 354 spring???

Postby pulltilbroke » Sat Aug 14, 2010 9:00 pm

IIRC I clipped 2 coils out of mine, Just set it next to your 366 or 386 spring and make it that length.

Why is everyone afraid of high rpms? You guys oughta try it its a whole lot of fun. :D



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Re: shortening the 354 spring???

Postby rattlebox93 » Sat Aug 14, 2010 9:03 pm

sweet thanks man and just for the reckord from what i understand the 1st gen has the best rods and the biggest main bolts out of any of the b series motors that have ever been put in dodge truck correct me if im wrong but thats just what i have heard
93 d350 extended cab dually, 5 speed, he351cw, industrial man ported, ported head, 60# springs, 6x16's, ballanced, coated slugs, lowerd comp, 354 spring, piston lp, 1/2 lines, con f, home made water in the works still not running but getting close
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Re: shortening the 354 spring???

Postby pulltilbroke » Sat Aug 14, 2010 9:51 pm

I have heard the same thing many times.

I believe the N/IC shortblocks were the best and stoutest ever put in a dodge and had better pistons from a performance standpoint.
90 W250 reg cab, Modified knuder valve, reversed reciprocting dinglearm adjusted, High volume flux capacitor,upgraded whirlygig, A clutch and a hitch
93 W350 ext cab dually, getrag and a few adjustments
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Re: shortening the 354 spring???

Postby 92 D/UNIT » Sun Aug 15, 2010 8:12 pm

I ran the 4200 spring. I did have to clip it to the right size. the truck ran better/different than it did with the 3200 spring. im not sure why, but it felt more responsive. and if anyone feels uncomfortable revving it that high, watch your tach.. :bom:
Brian 92 D 250 250K, A518, pump mods, BHAF, 4X15s, 4" turbo back dual exh, 3200 spring, HTB2 62/12.

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Re: shortening the 354 spring???

Postby Begle1 » Mon Aug 16, 2010 8:02 pm

Somebody needs to get all scientific and stuff and graph these springs' tension verse their given length... See what kind of fueling curve the actually give per RPM, to see if a 3200 RPM spring does actually act harder on a governor than a 4000 RPM governor spring...

Just need a caliper and a newton gauge thingy...

For an all-out performance stand-point you want a stiff spring that stays stiff right up until the RPM you want it to cut-out, right?

Although doesn't Hook's law kinda mean the springs' curves will all be linear and that you just want as stiff a spring as possible that is long enough to still give you full fulcrum lever travel?
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Re: shortening the 354 spring???

Postby BC847 » Tue Aug 17, 2010 7:56 pm

Begle1 wrote:Somebody needs to get all scientific and stuff and graph these springs' tension verse their given length... See what kind of fueling curve the actually give per RPM, to see if a 3200 RPM spring does actually act harder on a governor than a 4000 RPM governor spring...

Just need a caliper and a newton gauge thingy...

For an all-out performance stand-point you want a stiff spring that stays stiff right up until the RPM you want it to cut-out, right?

Although doesn't Hook's law kinda mean the springs' curves will all be linear and that you just want as stiff a spring as possible that is long enough to still give you full fulcrum lever travel?

So, . . . . . . has anyone else dinked around with the fly-weights of the mechanical governor? Lightening them would raise the fueling roll-off point. ;)
David

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