GMC 6-71 to street blower conversion

Compleate 6-71 , Street Conversion

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Original Parts:
Case, rotors, gears and 1 bearing plate ( preferably from same core)

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1. disassemble, Clean, check all dimensions

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2) Resurface top opening
3) Open up inlets
4) cut o-ring grove (optional)
5) clean/repair bolt holes

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5) resurface (as required)
6) machine bottom openings
7) remove side brackets (hangers)
8) cut o-ring grove (optional)

9) Bearing Plate

Option A:
Stock bearing plate (fine for street, but prone to cracking)
A1) plug oil gallery holes
A2) resurface as necessary
A3) new bearings/seals

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Option B:
Billet bearing plate
B1) new bearings/seals
B2) Machine Bearing registers
B3) Machine/setup dowel pins

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(We have found that most aftermarket plates are poorly machined
and the bearings wont set all the way down, the must be re machined )

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Tapered bore on new plate

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Repair new plate

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10) Rear bearing plate (aftermarket)
don’t bother with covering the original. it seldom works well
11) same machining problems as front
12) by replacing the front and rear dowel pins with larger pins, we can set
the bottom rotor clearances – this requires clamping the plates were
you want them and machining/reaming new dowel holes
13) also installing jacking screws , if you plan on using striped rotors

Rotors:

14) resurface rotors if needed
15) check all rotor clearances ( and adjust if necessary)
a) move rotors up and down in case (end plate dowel pins) sets
case clearance
b) front bearing shoulder on rotor shaft sets the front clearance
c) rotor length/ case length sets rear clearance
d) cut gear shoulder to set rotor/rotor clearance (timing)

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16) Polish (optional)
17) Assemble

Next:

snout, pulleys, tri cover, idler, brackets , …………..