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Rocker Arm Clearances

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Moseso

Moseso

Jedi Knight
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I have searched the Complete Official TR3 Workshop Manual, high and low, and cannot find this information. Anyone got a clue?

'59 TR3 Motor:
I am replacing the old scored-up rocker shaft and the rocker arm bushings. The new rocker shaft measures 0.6234". If I ream the new bushings to 0.6250 that will leave 0.0016" clearance. Is that the proper value? More? Less?
 
Don Elliott

Don Elliott

Obi Wan
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If I remember correctly, the rocker shaft does not rotate in the pedestals. Therefore they can be almost a light press fit. You will only need to rotate them once so that all the pedestal bases are flat on the bottom where they sit on the head when you tighten the assembly down. I would say "less clearance than you suggested".
 
OP
Moseso

Moseso

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Don --
Wrong parts, but thanks for trying. I know the pedestals should be a tight fit on the shaft.

It's the rocker arms -- which most assuredly DO move on the shaft -- that I want the clearances for. I replaced the bushings in the eight rocker arms -- 2 per arm -- and now need to ream them to some proper clearance on the arm. Right now they are .010" - .012" smaller than the diameter of the shaft -- and I know THAT'S not right...
 
OP
Moseso

Moseso

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Really????
No one has an answer for this????
 
P

piman

Darth Vader
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Hello Moseso,

I can't quote for a TR4, but for the Triumph six cylinder these are the official dimensions:-

Shaft diameter 0.5607" to 0.5612"

Rocker bore 0.562" to 0.563" 2000cc engine
0.563" to 0.564" 2500cc engine.

From that the maximum clearance is 0.0023" for a 2000 and 0.0033" for a 2500. Why there is a difference I don't know, seems rather odd?

Alec
 
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