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I have a 91 Suburban with a SBC 350 in it. I think that the crank bearings are wearing out because the crank pulley is shaking a bit, causing the idler pulley to constantly shake and odd wear marks to appear on other pulleys. So, when I pull the motor to rebuild it, I'm going to go ahead and try to build it up to produce as much low-end torque as possible. I'd build it up for the HP, but I have no interest in going more than 80-85, so I don't want/need top speed, but I'd like the get up and go. So, what can I do during my rebuild to get more torque out of it.

I think I am going to do some of the outer mods like:

install a K&N air filter assembly
swap to underdrive pulleys (don't understand the theory behind it, but if it frees up power, I'm for it)
install an electric water pump
somehow set up dual-alternators
possibly swap out to eletric fans (I don't know, I saw that it said don't use 'em if you plan to do heavy hauling)

so, anything else I can do to achieve my goal?
 

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I have a 91 Suburban with a SBC 350 in it. I think that the crank bearings are wearing out because the crank pulley is shaking a bit, causing the idler pulley to constantly shake and odd wear marks to appear on other pulleys. So, when I pull the motor to rebuild it, I'm going to go ahead and try to build it up to produce as much low-end torque as possible. I'd build it up for the HP, but I have no interest in going more than 80-85, so I don't want/need top speed, but I'd like the get up and go. So, what can I do during my rebuild to get more torque out of it.

I think I am going to do some of the outer mods like:

install a K&N air filter assembly
swap to underdrive pulleys (don't understand the theory behind it, but if it frees up power, I'm for it)
install an electric water pump
somehow set up dual-alternators
possibly swap out to eletric fans (I don't know, I saw that it said don't use 'em if you plan to do heavy hauling)

so, anything else I can do to achieve my goal?
I would think that if the main bearings were wearing out you'd hear it knock a little. It actually could be a few different things. At one point my water pump was on it's way out. Bearing went bad. prior to that happening my belt tensioner would hop a little. When the bearing finally went it would throw the belt.
Although I've never tested one, I hear that your harmonic balancer can go bad over time. The rubber cracks, and breaks away leaving gaps bewteen the weight, and the outer shell/ring. This would make an off center wobble, and could cause your belt to act like it is.

Harmonic Balancer
The harmonic balancer, also referred to as a vibration damper, is a device that is connected to the crankshaft in order to reduce the torsional vibration.

As the cylinders fire, power is transmitted through the crankshaft. Since the front of the crankshaft takes the brunt of this power, it often moves before the rear of the crankshaft. This causes a twisting motion. As the power is removed from the front, the halfway twisted shaft unwinds and snaps back in the opposite direction.
Although this unwinding process is quite small, it can cause "torsional vibration." To eliminate this vibration, a harmonic balancer is attached to the front part of the crankshaft that’s causing the trouble. The balancer is constructed of two pieces connected by rubber plugs, spring loaded friction discs, or both.
Therefore, when the power from the cylinder hits the front of the crankshaft, it tries to twist the heavy part of the damper. Instead, it ends up twisting the rubber or discs connecting the two parts of the damper. Since the front of the crank can’t speed up as much with the damper attached, the force is used to twist the rubber and speed up the damper wheel. This helps keep the crankshaft operation calm.
According to one parts manufacturer, replacement "harmonic balancers" are quickly becoming a hot item for today’s car owners. The reason is "harmonic vibrations," which can lead to a variety of mechanical failures. Harmonic vibrations are specific and repeated vibration patterns, which pass through an object. In today’s cars, such vibrations result from the combustion of the air-fuel mixture. Each time a cylinder fires, the connecting rod pounds the crankshaft journal as the force turns the crankshaft, causing energy to be dispersed throughout the engine. Multiply this by the number of cylinders (with variations in engine speed) and you have what is commonly called harmonic vibrations.

I think if you really want to torque your beast up, you'll need to do more internal tinkering, than external..Starting with Camshaft.
 

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Discussion Starter · #3 ·
well, I guess a harmonic balancer or water pump would be signifcantly cheaper than a rebuild, so I'll try to replace those. However, any suggestions on the main focus on the project are still very much welcomed so that I can have a reference when I'm ready to start the rebuild.
 

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Check the crank pulley itself, the bolts sometimes come loose and it's not unheard of for the mounting face to become bent.
 
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