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The "9m" valve adjusting tool

 
 
Old 11-17-2008, 01:25 PM
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Default The "9m" valve adjusting tool

Due to popular demand from another thread, here are the instructions to make your own degree method 911 valve adjusting tool. The theory behind this tool is to set the 0.1mm clearance of the cam follower by turning the valve adjuster screw exactly 1/10 of a turn (36 degrees) from a zero clearance position, it working out to a tenth due to the 1.0mm metric pitch of the adjuster thread.

Before I start though, can I just explain to all that this is not my idea, it actually came from a seasoned 911 specialist in South Africa who had been using his own version of the tool for over 30 years (thanks Brian), hence I can only take credit for bringing it to everyone's attention.

To make your own tool, all you need is a cheap flat blade screwdriver, a length of wire coathanger, a protractor, pen, paper, ruler, pliers and welder - all the stuff likely to be found lurking in any self respecting workshop.

Stage 1 is to draw out a 36 degree angle on the paper to use as a template:
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Old 11-17-2008, 01:31 PM
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Cut a 125mm (5") length of wire as shown above and file/grind points on the ends of the wire. Don't make them super sharp as it's not essential and probably undesirable for obvious reasons.

Next stage is to put the screwdriver in the vice and using a combination of brute strength or pliers, bend the wire around the round part of the blade to form your pointer. You have a choice here, I decided to do a proper engineering job and bend the pointer arms so that their centrelines were on the exact angle lines, but this is not essential and you could simply bend the wire into a V shape.

Check the angle of the finished item against the template, measure the distance between the points and make a note of the dimension.
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Old 11-17-2008, 01:33 PM
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Next you have to weld the pointer vee to the screwdriver blade. Don't make the mistake I did on my first one and leave the blade in the handle whilst you do it - 'cos it will melt when you weld it!

Here is my attrocious attempt at a TIG weld:
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Old 11-17-2008, 01:36 PM
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After quenching the blade (!) clean it and knock the handle back onto the end. During welding the wire will distort, so now you need to check the distance between the points to ensure the tool is exactly set to 36 degrees. If you forgot to make a note of it don'e panic, just punch a hole through the paper and use the template instead.
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Old 11-17-2008, 01:41 PM
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So there you have it, your very own "9m" degree method valve adjusting tool.

To adjust a valve, all you do now is to slacken the adjuster nut and tighten the screw until you have zero clearance. If you are not confident about what this feels like, fit a dial gauge and measure the opening of the valve, keep practising until you are happy that you have got the right feel. Once the valve is at zero, visually line up the left pointer with something on the cam carrier and then turn the screw until the other pointer lines up with the same mark; tighten the screw and you're done.
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Old 11-17-2008, 01:50 PM
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And if you can't gin up a protractor, take the pointer arm length (L) and multiply it by .618 to get the tip-to-tip pointers' gap...
[ie, tips' gap = L x 2 sin(18) = L x 0.618]

Assumes:
1) both your pointer arms are the same length, and
2) you're measuring their lengths (L) from screwdriver shaft-center to pointer tip.

[geektoid light off]
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Old 11-17-2008, 01:57 PM
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Or 36degrees is 6 seconds/minutes on a clock face.

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