Minimum valve clearance shim size for a fresh head?

[Fatmobile]

A guy at a local machine shop found a 1.5 head,.. and wanted to sell it to me cheap.
It's all rebuilt but I wanted to know how bad the cam rocked in it's saddle (due to a warped head), it wasn't bad.
I also wanted to know what clearance the valves had and the shim size.

None of the shims was over 3.55
and one was 3.25,.. that only leaves a few shims sizes for adjusting.
I haven't been keeping track of how quickly valves wear.
What is the minimum shim size you like to see for a fresh head?
Any idea how fast they wear?

[Quantum-man]

Interesting questions. My current head [AML], lost about 4 thou per valve over 20000 miles.
Can't find the piece of paper with trhe scrawl on it at the moment. Unless head runs dry and you wear the shims; I guess they don't change much... It's valve seat and head insert.
Does insert actually sink into the head if run hard due to the heat??
I ground the tip of a valve to put the gap back in spec on one valve. No regrets yet

[82vdub]

Two years ago when I checked the valve clearances, I needed some thinner shims. I found that a couple of the shims I had were thinner than what you could buy. I asked my mechanic what he did 6 years earlier (because the "rebuilt" head that I got had 4 valves that would not close) and he said that he had to shave a couple shims down to get the correct clearances. So, I did the same. I brought a few valve shims to a machinist and had them shave them down to xx.x mm, whatever thickness I needed them to be. I think I remember one being shaved down to 2.67mm.

Some on this forum said that there could be problems with the valve having been pulled to far into the head or something like that with this thin of a shim, or the shim coming out of the bucket, however, probably 15k+ miles on it with no issues.

As far as the shims wearing, any shims I've pulled out have always been within a couple thousanths of what the shim spec size was leading me to believe that if they do wear, they don't wear very fast.

[Quantum-man]

To machine a shim face parallel takes skill, money and time. To grind a little off the end of a valve takes me, some oily rag, a torch and a cheap dremmel.

If I want to fell Goliath, I aim for the kneecap, not the nose

[82vdub]

In my case, the head was on the motor, so it was cheaper and easier to modify the shim than the valve itself. But, either way will work.

[surfcam]

I can't see why a machine shop can't just take a bit off using a surface grinder with a magnetic table. Unless the shims are too hard. I bought some shims a while back. I bought some as small as 3-05 and big as 4-25. My heads all over the map kind of scary. I'm thinking I might have a sticky or bend valve. Last time I checked it, it was down to 4-10. The engine gets good mileage and sounds good when it runs.

[hagar]

Answer at hagar's ? 3.90 .

hagar.

PS : but hagar is an Old fusspot.

[Quantum-man]

In my case, the head was on the motor, so it was cheaper and easier to modify the shim than the valve itself. But, either way will work.

Mine was on the car too,I just needed to remove the cam, then the follower. Much more flesh on a shim to remove.

[82vdub]

Mine was on the car too,I just needed to remove the cam, then the follower. Much more flesh on a shim to remove.

And it was easier for me to drop the shims off at the machine shop over lunch and pick them up the next day. Then no extra work of removing the cam etc and messing with anything else. Works out the same in the end. I just have extra thin shims that I hope I never have to install in another head ever again.

FWIW, I found the bucket compressing tool frustrating to work with and found that compressed air removed the old shims in the head with the flick of the trigger on the air gun. Rotate the bucket so the notch is placed on your side, place the nose of the air gun by the notch in the bucket, pull the trigger and make sure you have your hand on the other side to catch the shim flying out the back side.

[Fatmobile]

3.9 seems a little high,.. but I suppose if I'm going to get 200,000 miles out of it before the next rebuild that might be about right.
Grind the shims too much and the cam will hit the bucket edge.
4 thousandths per 20,000 miles,.. How many shims sizes is that?

[VW Jon]

You can grind the buckets down, if you have to, due to grinding the shims down. The thinnest factory shim I know of is 2.8 mm, but I've ground them past that.

[VW Jon]

After 60,000 miles on my 1.5 head with new valves, the clearance has only been reduced by maybe .0005" on a couple valves. I always put new valves in when rebuilding any cylinder head.

[hagar]

both Injector shims and Valve shims can be done on a standard disc valve honing table.

I am in the process of using one of my many OLD turntables 33 is a good speed. BUT if you are in a hurry go 78.

VW Valve shims look a lot like some Air and Ammonia compressors Valves I fooled around with.

All the old Rabbits are loaded with perfect Thin spring steel washers for doing Injectors.
did hagar ever test them ? many times.

hagar.

[Quantum-man]

All the old Rabbits are loaded with perfect Thin spring steel washers for doing Injectors.
did hagar ever test them ? many times.

hagar.

?? Tape measure ??

[hagar]

Mark Shepherd UK " Tape Measure " ? great idea , count me in.

hagar.