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...
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wrote:

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 www.thesnoman.com
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What heads? What induction system? What for headers and exhaust?

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On Mon, 22 May 2006 11:15:06 -0500, "Shades" <shades_1970(at)netins(dot)net> wrote:>What heads? What induction system? What for headers and exhaust?
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 www.thesnoman.com
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I am trying to think of a GM product with a GVW of 11K available in 4X4? With a turbo 400? Pulling a total weight of 21K? If you manage to keep that tranny together, which is unlikely, I can't think of any combination that would produce enough TQ to move that kind of weight. Maybe if you were working with more torque multipliers (gears) maybe.A good big block may produce enough torque to lug that beast down the road but it wouldn't do it well. 10.5 tons with a automatic, think that over before you go any further. Yea a 400 will handle that kind of abuse for short durations in a race application but put in on a highway @ 55 tugging 10 tons for 30 miles. A extremely large tranny cooler might keep ya going but I wouldn't hold my breath. As far as the engine goes you can build a small block to move it but you won't be happy. I had a 86 Ford 1 Ton that I would haul 6-7 tons of gravel in. Equipped with a 300 6. It would go down the road but that was about it. It had a 5 speed with a deep reduction 1st and 4.8 gears in the rear. But if you want to go on with it here are my suggestions. The pistons you choose will depend on your heads. I would keep my static compression below 9.5 because you are going to be lugging this motor alot. You don't want to risk detonation. Use a head with a small intake runner, for low RPM, high torque I would try to stay around 165-170 cc runners. That will help you build intake velocity at low RPM's keeping your VE higher. Stay with either stock manifold or small tube headers. Cam selection will depend on your final engine combination. Keep your duration below 210 @ .5 lift and your lobe seperation around 110. There are some dual pattern cams out there that would work also but you don't need any high RPM's. Your lobe seperation is probably the most important issue. Big lopey cams build power by using scavaging to build Hp and Tq in high RPM's but sacrifice the bottom end becuase the intake valves remain open during the start of the piston upstroke. If you can latch onto a good newer small block with factory roller cam you have more options. You can run a higher lift and slightly wider seperation because the lifters can work at sharper angles without the use of extremely stiff springs and not slam your valves down like a flat tappet cam's will. And finally if I was really looking for low RPM grunt out of a small block I would consider transplanting a TPI system onto that motor. Those long small runners and long plenum combined with proper heads really get that intake velocity going, especially at low RPM's. Like I said these are my opinions, just opinions.

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On Mon, 22 May 2006 16:04:40 -0400, "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 www.thesnoman.com
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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 4X4 with a 400. Now a 3/4 or 1 ton truck with 4 tons in the back would put it @ 11K or better, I can see that. I still don't think a 400 or any other auto in this class would be well suited for the job. The 5+2 combo that you talked about earlier is more along the line. But that would be hard to get a two speed front and rear. A good 5 speed would be a good option for this particular truck. But saying all of that I have never had any experience with a 400 trying to do that kind of work, 3 gears just don't suit me in a heavy vehicle. Of course I drive a vehicle with 1700 lbs torque and 15 gears running into 3:36 rears. Final drive ratio's will get you moving it doesnt really matter if they come from the tranny or rear it still comes out the same.
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On Mon, 22 May 2006 18:53:24 -0400, "David Johnson"

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 www.thesnoman.com
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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...

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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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No substitute for cubic inches and/or a long stroke engine for pulling/work torque.

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