924Board.org

[Mike924]

Pulled the camshaft off my car (more on which later...) and in an idle moment, I thought I'd measure up the adjuster screws for reference:

length: 22.75 mm, diameter: 6.5 mm (ish)

thread pitch: 0.75 mm

adjustment slope: 3 degrees, giving 0.04 mm per turn (Haynes manual says 0.05 mm, so I'm probably out by a bit)

The boss in the tappet that the adjuster screws into is 18.3 mm in diameter (as close as I can measure it), with a wall thickness of 4 mm.

This would indicate that the adjustment range is 4.45 mm (22.75 - 18.3), or 6 turns (or 'clicks'). From Smoothie's measurements of the T77H adjuster tool, it would appear that 6 mm (8 turns) is the permissible range. I guess this allows for the end of the adjuster screw to be one turn further in or out from the outer edge of the wall.

But, with the screw at these limits, I measure between 8 mm (all the way out) and 14 mm (fully in) between bottom of the Allen key 'hole' and the outside of the tappet. The limits indicated on Smoothie's adjuster would allow the screw to go in fully 2.5 mm further than this, leaving (by my measurements) only one thread holding one end of the screw in.

I'm not saying Smoothie's got anything wrong (far from it!), just something to be be aware of.
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1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[Ozzie]

those adjusters come in 4 sizes IIRC.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Tigger937]

[Smoothie]

Very good to know. Could'a, maybe should'a tacked this onto that other thread. I added a link from there to here..
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[Mike924]

[Mike924]

[Ozzie]

My point is you have to take the adjusters to the limit eithir end you should look at going up/down a size
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Mike924]

[Ozzie]

Point taken, not having adjusted mine, I would still prefer to have the adjuster somewhere close to the middle of the range of movement when I do.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

[Mike924]

Absolutely.

The other dimension, then, is what is the step in thickness between the different 'notch' sizes of the adjusters.

I will attempt to answer this empirically if I get time to rip out the remaining tappets this weekend.
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[Mike924]

Right, while I had the camshaft and all the adjusters out, I decided to do a survey of the adjuster thicknesses. I measured the thickness of the 'fat' end of two sets of adjusters (minus one), between the flat and the outside of the threaded portion. Here's what I got:

No notches:
6.71 mm
6.65 mm
6.70 mm
6.65 mm
6.58 mm
6.58 mm

1 notch:
6.75 mm
6.75 mm
6.77 mm
6.77 mm

2 notches:
6.98 mm
6.88 mm
6.91 mm

3 notches:
6.99 mm

Given the range of thickness in each 'class', I get the impression that the adjusters are not so much 'stepped' in size, but graded, probably into 0.1-0.2 mm wide bands. Notice the difference between the thickest 2-notcher and the single 3-notcher I had is only 0.01 mm! Also the difference between a zero-notcher and a 1-notcher can be as little as 0.04 mm or as much as 0.19 mm.

Just something else to be wary of...
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[morghen]

[quote="how far can you 'push' an adjuster before needing to go the the next size?[/quote]

to the point that it is maxed out its height using the bolt inside them and it still does meet the valve clearence necesary. after this...you need bigger ones.
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Supercharger and EFI kits
https://www.the924.com

[Mike924]

Possibly, Morghen...

But, the thing is, that pushing them that far, the next size up might not get you very far. You might need to go up two, or even three( ), sizes to get back into the middle of the adjustment range, based on the measurements I did.
_________________
1985 Porsche 924 'Lux', Kalahari Beige (my ex)
1993 Porsche 968 Coupe, Midnight Blue, 6 spd

'There is no substitute for a little grease under your fingernails.' - Chrenan, 924board.org

[Benino]

This is not taking into account the variance between any 2 screws with the same number of notches.
I adjusted my valves a few days ago. One screw was in really far. I screwed it in one full turn (one click). At this point it was so close to coming out the hole on the other side that I wouldn't want to turn it one more for fear that it would scratch the side walls. This tightened up the measurements to within specifications, but I wasn't too comfortable with it being in that far. I replaced that 0 notch screw with a 1 notcher. The screw is now a bit beyond center. I felt like I could have put in a 2 notcher, but am comfortable with how far it screwed in (didn't go in too far for comfort).
I didn't make any measurements of the screws I used but I just thought I'd share my experience of going from one screw to the next. Next time I go from a completely maxed screw to the next one I think I'll go two steps up.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

[Mike924]