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...
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)
On Mon, 22 May 2006 11:15:06 -0500, "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
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.
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
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
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
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...
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
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
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