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General Category => General Discussion => Topic started by: Stevex on July 13, 2020, 05:52:53 AM

Title: Valve spring shimming
Post by: Stevex on July 13, 2020, 05:52:53 AM

I'm going to be sending my LM2 heads for refurb this winter. New valves, springs and collets and guides K lined with seats re cut.
Am I right in believing the outer valve spring length when refitted needs shimming to obtain a length of 36.7mm - 37mm?
How is an easy way to measure this accurately?

Title: Re: Valve spring shimming
Post by: lucky phil on July 13, 2020, 07:20:15 AM

Quote from: Stevex on July 13, 2020, 05:52:53 AM

I'm going to be sending my LM2 heads for refurb this winter. New valves, springs and collets and guides K lined with seats re cut.
Am I right in believing the outer valve spring length when refitted needs shimming to obtain a length of 36.7mm - 37mm?
How is an easy way to measure this accurately?

Install the valve in the head without the spring and seat the retainer and collets after installing a spring shim on the head. Hold the valve closed and use a 6" caliper to measure between the spring shim and the spring seating face on the spring retainer then calculate the additional shims/s you will need of preferably a single thicker/thinner shim.

Ciao   

Title: Re: Valve spring shimming
Post by: Stevex on July 13, 2020, 08:26:58 AM

👍Thanks. Les, that's  one pristine head you've got there.

Title: Re: Valve spring shimming
Post by: Antietam Classic Cycle on July 13, 2020, 08:53:05 AM

Quote from: lucky phil on July 13, 2020, 07:20:15 AM

Install the valve in the head without the spring and seat the retainer and collets after installing a spring shim on the head. Hold the valve closed and use a 6" caliper to measure between the spring shim and the spring seating face on the spring retainer then calculate the additional shims/s you will need of preferably a single thicker/thinner shim.

Ciao

This ^^^