Valve Adjustment Question
Moderator: Fatmobile
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- Glow Plug
- Posts: 6
- Joined: Mon Sep 28, 2015 8:22 pm
- Location: Lakewood, Ohio
Valve Adjustment Question
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.
1.6 diesel with mechanical lifters
4 speed (4A) transmission
377,000 miles on body, original transmision, second engine.
Re: Valve Adjustment Question
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.
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.
J.R.
SoCal
SoCal
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- Cetane Booster
- Posts: 40
- Joined: Sat Sep 28, 2013 4:40 pm
Re: Valve Adjustment Question
Shoot for 0.010 inch for intakes and 0.018 inch for exhaust...period.
Always perform a quick check of thickness with a caliper.
Always perform a quick check of thickness with a caliper.
Re: Valve Adjustment Question
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.
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.
I have too many to count
I have too many to count
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- Global Moderator
- Posts: 7565
- Joined: Wed Oct 30, 2002 10:28 pm
- Location: north central Iowa
Re: Valve Adjustment Question
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.
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.
'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.
Re: Valve Adjustment Question
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.
I have too many to count
I have too many to count
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- Global Moderator
- Posts: 7565
- Joined: Wed Oct 30, 2002 10:28 pm
- Location: north central Iowa
Re: Valve Adjustment Question
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.
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.
'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.