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Mon Dec 01, 2003 9:30 am

I adjusted my valves for the first time yesterday armed with my new
John Muir Idiot book. It was easier than I had expected.

During this adjustment I realized that all my valves were previously set too tight, I couldn't get the feeler to slide between any of them.

I read in the book that it's better to have them too loose than too tight.
Just curious what negative side affects would you get from having them too tight?

Mon Dec 01, 2003 9:40 am

Too tight= more heat transfer and a quicker opening valve. It's better to have your intakes a little tight and your exhaust a little loose if you had to. Just do them right and don't look back!

Mon Dec 01, 2003 9:42 am

Did you ever replace your heads? did you just do them recently? or ?

Mon Dec 01, 2003 10:01 am

I tapped the plug hole and put an instert in. It's a temporary fix until
I get the new heads. While I was doing this I noticed that there is a small crack around the plug hole. Not sure if It goes all the way throught but I can still hear a small amout of breathing when I turn the engine by hand.

Mon Dec 01, 2003 10:26 am

Good job on getting your valves adjusted. Your on your way to becoming an expert. Watch out for number 3, that is usually the first one to get out of wack.

As for too tight, crofty is correct. What you need to realize about being to tight is that it means a hotter engine. To make it simple if your valves are too tight, then the heat can't escape. I tune my valves based on what time of year it is. Now I go for around .006, but in the summer for some hot road trips I set it closer to .007 or .008.

As for the book, get the big green one, it will help you out with the rest of the bus. I can't remember the name and the book is out in the bus.

Mon Dec 01, 2003 10:40 am

The Green one is the Bentley, an excellent addition to the Muir, between the two books, you'll have most of the info you'll need for your bus, the rest, you come here for! Jeremy

Mon Dec 01, 2003 11:10 am

llamas1 wrote: .
Just curious what negative side affects would you get from having them too tight?

Two disasters can occur with tight adjustments:
Tight adjustments cause the valve to be off the seat for a greater duration of the cam's circle. This means the valve absorbs more heat than it can shed during the seated time interval. This will lead to metallurgical valve failure particularly with the hotter exhaust valve.
This problem sneaks up out of the blue and is the cause of the mysterious "dropped valve" failures. Engine can run fine, as a matter of fact, it will be nice and quiet while it destroys the valve from within.

Tight adjustments can also cause the valve to burn at the margin creating a loss of compression that will be noticeable to the alert driver. The reason for the burn-through is the same as the above, the valve has no time to shed its heat if it expands to such an extent that it doesn't even contact the seat when closed. This type of failure buys you a little time at least to get a valve job done at your earliest convenience.

For the stock aluminum pushrod engines, .006" at TDC is the recommended clearance. There is a lot of blather about finding the exact base of the base circle before adjusting the valves, such as adjusting the valve only when it's opposite is fully open. This can limit "seat time" for cooling purposes. I say enjoy the clatter and adjust at TDC .006"
Colin

Mon Dec 01, 2003 11:31 am

Yes, I also read that earlier VW publications reccoment .004 but later
findings say to go with .006 Better for the valves but a little more noise
from the valves. After the adjustment I noticed that the engine ran
more smooth but with a little more clatter. I'm ok with that.

Anyhow I do have both books now, the Bentley and Muirs book.
I must say that the John Muir book is a little more entertaining of the two.

Mon Dec 01, 2003 3:40 pm

When all the valves are tight either it has been a very long time since they were adjusted or in many cases it means the heads are loose due to the studs stretching form the heat.

I always remove the rocker arms and check the torque of the 4 head nuts before adjusting the valves ( check both sides first then adjust)
remember 18 ft lbs for small studs8mm and 23 for large 10mm and maybe 25 if you have case savers.

another thing is that sticking in the .006 blade can still yield more than .006... why? well because sometimes the end of the vavle stem is dished in a bit from the screw pounding on it ( especially if it was ever set or got too loose) and the ends of the screws are often distorted.

when you have the rockers off, inspect the ends of the valve stems carefully and the condition of the adjusting screws... "lash caps" are available for the ends of the valves and new screws can be had or even better ( IMO) is the swivel foot adjuster.

after you adjust the 2 on ( any) cylinder grab the rocker and push pull it and listen to the noise... sometimes you can hear and feel that even though the gauge said .006( the gauge is laying flat around the outer " rim" of the valve stem and cannot read the low dished out spot of the worn stem thus more tolerance exisits) one may be much looser than the other... I always adjust those up a tad more till they feel the same.