Valve Adjustment Question

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dieselVinceOH
Glow Plug
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Location: Lakewood, Ohio

Valve Adjustment Question

Post by dieselVinceOH »

So I recently had my engine rebuilt. It's just hit 1,000 miles and it's time to do a valve adjustment. I have measured my clearances, and I removed the adjustment shims to see what thickness they were. However, I've never had to do a valve adjustment before, just checked them. I don't know exactly what the best measurement is for the valves on the 1.6. Should they be on the tight side (I'm afraid of burning a valve), loose side I don't want a valve hitting the pistons) or right in the middle?
1984 VW Rabbit L
1.6 diesel with mechanical lifters
4 speed (4A) transmission
377,000 miles on body, original transmision, second engine.
vwtyp133
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Re: Valve Adjustment Question

Post by vwtyp133 »

The "middle" is always a nice goal, but sometimes hard to achieve. A bit 'too loose' would theoretically reduce - not increase a valve's maximum opening - so no added danger of a valve kissing a piston. 'Too tight'... avoid this by using honest measurements and obtaining the right shim; it's a PITA to have to wait for the right shim, but do it! If a substitution IS absolutely required, obviously err with a shade looser. That may mean you have to keep the revs down just a little until you get the correct shim. Added precaution: measure each shim before installation; most, but not all shims are accurately marked!

BTW - there are undoubtedly contributors to this forum who can accurately machine a standard off-the-shelf shim to a 'custom' thickness. Personally, I've tried 'ghetto machining' shims with grinders, sanders, wet-r-dry & my flat marble plate, etc... all without success. :roll:
J.R.
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Prairieview
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Re: Valve Adjustment Question

Post by Prairieview »

Shoot for 0.010 inch for intakes and 0.018 inch for exhaust...period.
Always perform a quick check of thickness with a caliper.
82vdub
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Re: Valve Adjustment Question

Post by 82vdub »

As the valvetrain wears, the valve clearance gets tighter. So, if you go to one direction, tighter will only result in needing service more often.

The last head I put on ole 82 wasn't properly rebuilt by the manufacturer. It had already passed warranty period, so I was stuck paying for the fix myself. Anyways, 3 of the valves never closed, so the head wasn't properly checked for proper lifter clearance. I was stuck with a head that needed very thin shims, too thin for any factory shim available. So I brought shims to a machine shop that has a magnetic table and it was no problem for them to machine them to the thickness that I needed.
Everybody else lists their cars here - but not me.

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Fatmobile
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Re: Valve Adjustment Question

Post by Fatmobile »

Or a small portion can be machined off the end of the valve; if the shims are too thin.
Most machine shops can do this.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
82vdub
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Re: Valve Adjustment Question

Post by 82vdub »

That's true too. I didn't want to disassemble the head since the head was still on the car.
Everybody else lists their cars here - but not me.

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Fatmobile
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Re: Valve Adjustment Question

Post by Fatmobile »

Right, pull the valve and you need to replace the seal.
At least mine got ripped-up when I pulled the valve through it. Can't cover the grooves with a little cap like when the valves are installed.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
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