At every Super Chevy Show we see quite a few blown, Pro-Street machines. In fact, those of you who attend these oh-so-cool events know that we have an entire class labeled "Pro Street" in the award classification. The part we don't always think about is how these awesome blown machines run after years on the road. Many of these tubbed beasts have been on the highway for 15 or 20 years, possibly without ever having been freshened up. After a recent trip to Littlefield Superchargers we learned that the lifecycle of a blower is shorter than one might expect. Just as all engines wear out rings and bearings, the same can be said for the internal components of a supercharger.
Our project motor originated as a 427-inch Rat with a Littlefield 6-71 supercharger, Holley Dominator carburetors, Vertex magneto, solid-lifter camshaft, and GM rectangular port heads. After 20 years of reliable service, our little huffer motor finally took a dive off the deep end and ate a piston. After sitting on the engine stand for a few years we knew the time had come to give the ailing 427 a proper revival. However, this time we had the advantage of a modern Lunati solid-roller bumpstick, MSD electronic boost control ignition, Holley blower-specific carburetors, JE forged-blower pistons and overall better technology in the manufacturing of our components.
The blower drive was the first part to be removed.
We began the overhaul by showing up at the doorstep of Mert Littlefield for a class on supercharging 101, the proper way to rebuild a 6-71 blower. As it turns out, what we thought was a routine check-up turned out to be major surgery. After removing the front bearing plate, we discovered that at one point in time the right upper rotor had actually spun a bearing, a rare ailment among 6-71 blowers according to Mert.
By the end of the day, all was well and our 6-71 was once again ready for action and awaiting its new destiny atop a freshened 427 long-block. Stay tuned as next month we will be assembling the rest of our street machine 427 and heading to Vrbancic Brothers Racing for a little fact or fiction on Vrbancic's engine dyno.
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With the drive removed, the gears can be pulled from the rotors. Older units such as ours
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After removing the front bearing plate we were stunned to find that the upper rotor had sp
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The rear rotor access plates were removed so that the rotors could be tapped out.
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The damage to the rear plate was caused by unwanted thrust of the upper rotor, an effect o
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The rear bearing plate was flycut .035 inches to remove the rotor inflicted damage.
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After the rear plate was surfaced and pressure washed, the new bearings were pressed into
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A new front bearing plate was required to safely house the fresh bearings.
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The rotor ends were surfaced to remove the damaged material. The amount of material remove
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The outer edges of the rotors were machined .010 inches before the new Nylatron was instal