High Torque SBC help

Anyone in here ever build a super torque 350 engine ? We are building one right now for a 11,000# dump truck that pulls a 10,000 # trailer. We have the option of dished or flat top, we were planning on flat tops with this cam... 204/214 dur @ .050, 270/280 adv dur., .420/.443 lift, 112 lobe sep. and then having the computer worked over by pcm4less or someone that can make one for our app. (haven't talked to them about it yet) The 4x4 dump has

4:11 gears and a turbo 400 P.S. we were thinking of stroking it to a 383 but if we are going that far I might as well drop our good 427 tall deck in... Any help is appreciated... Thanks...
Reply to
69SScamaro
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There is a far simpler fix heare as you are going about this wrong. Try at least some 4.88 or 5.13 gears in it because you will never get enough torque out of a SB to move it properly with 4.10. Re gear it and limit duration to 260 and it will do okay. More duration than this will kill low end torque. Even with a 454 I would suggest a 4.56 if you want it to motivate properly. Gears will help it a lot as that small block will move it okay IF you gear it properly. Back in 70's I drove a 366 powered single axle C60 and a C70 triaxle 427 powered one. WIth the C60 I use to tow a float with a backhoe on it at time and have a GCW above 40k at times too and it did surprizing well because it had proper gearing, a 10 speed (5x2). the C70 had a 20 sp (5x4)

----------------- The SnoMan

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SnoMan

What heads? What induction system? What for headers and exhaust?

Reply to
Shades

None of this will make the torque needed to move 20k plus effectively with 4.10 gears and a SB but there are those that alway ignore the obvious "fix" and look for magic bolt ons

----------------- The SnoMan

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SnoMan

Reply to
David Johnson

Gee many years ago I used to work in farm operations (late 70's to mid

80's) and we used to haul grain trailers weighing up to 23k with a combined GVW of around 30k or more with a 72 GMC 3/4 4x4 with a 4.10 and a SM465 granny gear tranny and a 79 J20 jeep with a 360 and a THM 400 and 4.10's too. Granted we did not towing cross country and never exceed 45 or so (deepr axle gears were really needed for higher speeds too) with those loads but we would make several trips a day for several weeks for many years and never had first problem with either trucks driveline. I later pressed the J20 Jeep into snowplow duty for many years until I retired it a few years ago to restore but its THM 400 is still stock and works fine (it has had a small aux tranny cooler on it since day one). If I was going to haul 20K plus regulalry with a small block at speed if you had enough gearing it would work okay. The THM400 is aurguably one of the strongest trannies of its type and powered many motors home towing cars for many yrears without problems becuase these motor homes had 4.56, 4.88 or 5.13 gears too. Just think of deeper gears as giving you a lower pry bar (more leverage or mechanical advantage) to place against the load

----------------- The SnoMan

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SnoMan

Can't argue that a higher ratio would not help him. Would probably benifit greatly from a ratio change. The 400 is one of chevy's strongest auto's. I guess when I read a 11000 dump truck I was thinking just the weight of the truck. Wouldn't that be a class 5 truck. That is where I can't think of a

Reply to
David Johnson

It is a K30 with 11,000 GVW I have overloaded it many times and pull a skidsteer on a trailer behind it. It has a 12 foot dump bed so it is very easy to overload. I just hauled 12 yds. of mulch with it today. The engine I have in it right now is one that I thru together for a 1/2 ton truck, the cam is a stock TBI cam and it pulls ok I just want a little more... As far as the trans it is great... it has the 205 NP transfer case Dana 60 in the front. Would be tough to try any type overdrive... right now with the

4:11's it screams going down the highway pretty good. I had 5:43's in my 454 Camaro and I know how bad that screamed at 55. I'm not used to building a torque engine... I've built about 1,000 engines in my time in the garage, but we just put them back to what they were stock. As far as my engines they were all made to scream. Even my 454 turned 7,500 rpm's... My 69 camaro I built a 383 stroker with Dart heads and a cam that has 292 dur. @ 0.50 it chops a little... lol Brother in-law has a 84 454 11,000 # 4x4 dump with 4:56's and he can light up the tires. No end to power, just hogs gas like it's free. Basically why I don't want to build the 427 TD ... I think you guys are definitely onto some of it with the gears. I'll throw the original engine back together with some of the stuff you guys mentioned and see what happens. Also I have the original exhaust, TBI injection, even air pump... The pump for the fisher plow I have the belt off for the summer. I'll keep you informed of how it turns out... Thanks...
Reply to
69SScamaro

Don't under estimate the old 366 chevy...you should be able to find one of those fairly easy..with very little work, that engine will haul almost anything... i worked for a school bus company for awile in the late 90's and all of our fleet had 366's and a couple had turbo deisels... the gas engines far out performed the diesels...they were available at least into the late mid 90's...most of them had holley carbs (that required allittle mod, to perform) and some were fuel injected...shouldn't be that hard to find

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redeye-racing

Reply to
Shep

Not really because with tall axles and compaund trannies you have a lot of drive line torque and chassis twist while deeper axle gears reduce driveline torque load for same grond tractive effort. The c60

366 powered dump I drove long ago had a two speed axle with a low of around 10 to 1 and high around 7 to 1

----------------- The SnoMan

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SnoMan

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