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Installing Crankshaft Pulley
Posted by: Frog ()
Date: April 16, 2018 05:18AM

This might be another everbody-understands-it-but-me question:

On page 6A-52 of the 1961 shop manual, paragraph 37 describes the procedure for installing the crankshaft pulley. It says: "Draw crankshaft pulley into place on crankshaft, by turning retaining bolt until crankshaft pulley bottoms in place."

O.K. It get that; it's obvious to me.

Here's the phrase I don't get: "Back crankshaft pulley retaining bolt off one turn and torque to 40 to 50 ft. lbs."

Why back the bolt off a turn? Why not just continue tightening up to the specified torque setting?

Thank you.

Frog

Rob Lane
Clayton, in the Northeast Georgia Mountains.
1964 500 Coupe
Purchased by me in April of 1964.

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Re: Installing Crankshaft Pulley
Posted by: Murphy ()
Date: April 16, 2018 05:33AM

Engineer verbiage. You're not alone.

65 Monza Coupe
61 500 Coupe (under Construction) Getting close.

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Re: Installing Crankshaft Pulley
Posted by: JerryM ()
Date: April 16, 2018 07:16AM

That's a common practice for electrical connections because the surface of mating parts usually have some type of plating and friction gives a false reading. So loosening then re-torqueing yields better bolt tension indication.
Maybe the designers felt the process of drawing up the pulley did something similar?

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Re: Installing Crankshaft Pulley
Posted by: cnicol ()
Date: April 16, 2018 07:51AM

If the pulley won't slip on far enough to engage the standard-length bolt, I often start the process with a little longer bolt and then switch to the standard bolt. You don't want to strip-out the crankshaft threads! DAMHIK

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Installing Crankshaft Pulley
Posted by: 66vairman ()
Date: April 16, 2018 08:51AM

Jerry and Craig are both correct.

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Re: Installing Crankshaft Pulley
Posted by: oldqmguy ()
Date: April 16, 2018 10:28AM

I was told by a "real Corvair mechanic" (he worked in a Chevy dealership in Northern Indiana many years ago) that this was to prevent the Bolt from being left "over torqued!" drinking smiley

He said that most mechanics used a LOT of force getting the pulley seated. If they followed the instructions in the Manual the final torque would be correct. spinning smiley sticking its tongue out

It doesn't take much extra time and like Craig said, you really don't want to damage the Crankshaft threads!! grinning smiley

Dale cool smiley

Dale E. Smiley CPBE
Life Member The Society of Broadcast Engineers
RETIRED Broadcast Engineer
CERTIFIED CORVAIR NUT
CORSA/Circle City Corvairs/Corvair Performance Group
Avon, Indiana
WB9SFF
1967 4-Door Monza PG!

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Re: Installing Crankshaft Pulley
Posted by: Frog ()
Date: April 16, 2018 10:31AM

Thanks for the explanations.

I'm going to follow your tip, Craig, and get a longer bolt to start this process.

Regards,

Frog

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