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Discussion Starter #1
Have been checking the valve clearances on my Giulietta. Five out of the 8 valves require shims below 1.50 mm. The range of available shims is 1.50 to 3.50 mm. Some of the existing shims are below 1.5 so I guess they've been machined in the past. The biggest shim fitted is 1.99 mm and the smallest 1.13 mm.
The cylinder head was re-furbished a year ago with the seats re-cut.

  • Are the small shim sizes just a reflection of the valve seats being re-cut?
  • Have the valve seats been cut too far?
  • What's the thinnest shim size you can safely go to without them becoming weakened (I need one at 1.05 mm)?

Any advice appreciated.
If anyone has any shims lying about they don't need, I would be keen to buy them.
 

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The smallest shim available is 1.3 mm actually.

If you require thinner than 1.3 mm, to make the valve gap correct, you are better off in that case with shaving a bit off the valve stem-that should do the trick and allow a normal shim. Of course it means the head has to come off! A bit of maths and you will get it perfect!
As you suspect, most probably the valve seats have been recut a couple of times so the gap between end of valve and tappet cover is too little.
You will get shims from the usual suspects, but if not try this:
Alfa Romeo, Fiat and Lancia Individual Valve Shims -

http://www.international-auto.com/index.cfm?fa=ad&aid=186
 

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Discussion Starter #3
Thanks for the response.
have re-built engine, re-checked measurements, and stripped again.
Using the smallest existing shim I have (1.138 mm), and buying some new ones (some of which I will machine) I should be able to acheive the following clearances:-

Inlets ranging from 0.370 to 0.375 mm.
Exhausts ranging from 0.462 to 0.482 mm.

Inlets should be 0.4 to 0.45 mm so between 0.025 and 0.03 tight.
Exhausts should be 0.45 to 0.5 mm so no problem.

When I first checked the clearances a few weeks ago, the engine had done approx. 1500 miles since head re-build. The exhausts were all fine but the inlets were in the range 0.3 to 0.35. So between 0.05 and 0.1 tight!
I guess the guy that did the head realised the shims were getting a bit thin. Either that or he was working to the wrong figure for the inlets?!
I'm not taking the head of again to machine valves, so will go with the above clearances and see how it goes.
 

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Several Historic Racing Alfisti, here in Denmark at least, goes down to 0,25 mm on inlets, probably a bit more on exhaust valves. They claim that the clearance increases when hot.
Just check clearances every now and then, I do it once a year or about 3-4000 miles. Mine 1750 is 0,425 inlet and 0,50-0,525 exhaust.
Erik
 

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Discussion Starter #5
The smallest shim available is 1.3 mm actually.

If you require thinner than 1.3 mm, to make the valve gap correct, you are better off in that case with shaving a bit off the valve stem-that should do the trick and allow a normal shim. Of course it means the head has to come off! A bit of maths and you will get it perfect!
As you suspect, most probably the valve seats have been recut a couple of times so the gap between end of valve and tappet cover is too little.
You will get shims from the usual suspects, but if not try this:
Alfa Romeo, Fiat and Lancia Individual Valve Shims -

Adjusting Valve Clearances
Hi spiderserie4
Engine running again tonight. Here's what I ended up with:-
Inlets:-
1 0.41 with a 1.450 shim.
2 0.39 with a 1.375 shim.
3 0.41 with a 1.138 shim.
4 0.39 with a 1.450 shim.

Exhausts:-
1 0.49 with a 1.282 shim.
2 0.49 with a 1.530 shim.
3 0.495 with a 1.900 shim.
4 0.49 with a 1.725 shim.

Obviously the 2 shims that are below 1.3 are a bit of a worry. The UK specialists all told me that shims were only available down to 1.5. One specialist told me if shims were required below 1.5 then a head re-build was required.
I ordered shims from IAP from your link. Great service.
The engine is running really sweetly with less noticeable spitting back when cold.
Could get 2 and 4 inlet clearances into spec but the 4 clearances are pretty close to each other and the engine seems real happy so I think I'll leave it for now and re-check once I've put a bit of mileage on it.
 
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