Valve Shims

[SpyderJoe]

Hey all,
2 liter is out of my 79. It is getting new 9.8:1 pistons, higher compression cams and twin 40 idf's. Question on valve shims. The mechanic working on it is saying I need valve shims with thicknesses ranging from .201" - 0.21", which I believe are hard to get?? Does anyone make shim kits for Fiat engines with those thicknesses? If not, I guess my only option is to grind the cam boxes or longer valve stems. Thoughts?

Thanks

[BEEK]

shims are available to 5.20 mm. I would not run shims that thick though.the reason is the weight of the shim in a high performance application I would recommend milling the cam housings and getting adjustable cam gears. The only other alternative is longer valve stems. That would be pretty expensive having longer valves custom made. But it is possible.

[klweimer]

I think I would just go with the slightly thicker shims and call it good. I think the percentage weight difference between shim thickness, when added to the weight of the cam bucket is pretty small. Personal opinion.
Kirk

[fiat218]

I was told to go thinner ,hmm I can't recall right off hand in what size , but I think I would do as I'm told ,because I know nothing

[RRoller123]

I suppose you could add valve stem hats.

[narfire]

Careful with too thin as well. The lobe can contact the rim of the bucket before riding up on the shim....
I'm not sure about this but I thought the fellow doing the valves could deal with a preferred shim thickness range by fiddling with the installed heights of the valves.

[SpyderJoe]

Fiat218: I am in the same boat. I am not the expert.

I am kinda shying away from milling the cam boxes and using adjustable gears but what do I know I like the idea of valve stem hats. Where can I get those RRoller?

Beek, Where can I buy the 5.2mm thick shim kit?

As always, a lot of good advice on this forum. Thank you

[RRoller123]

"OE type shims thinner than 3.25mm MUST NOT be used or the cam nose will hit the bucket" Guy Croft.

The valve stem hats are mentioned in Guy Croft's book, but I have no knowledge of their use whatsoever.

[BEEK]

in a high performance build we did many years ago , we used alfa shims (stem caps) to make the fiat shim smaller and stay on the low range of the fiat thickness. Unfortunately we had one of the alfa shims split. I was assuming that there was a issue with doing this and never went back to that technology. After thinking about it in retrospect, we did use used shim buckets and they do wear and are not perfect at the valve mating surface. That may have been the cause of the failure but i have never tried again.

[fiat218]

http://www.burtonpower.com/tappet-shim- ... fb907.html

[fiat218]

Makes me wonder if my heads done yet

[fiat218]

[quote="fiat218"]

[klweimer]

AR has individual shims up to 5.20 mm., which is slightly less than 0.210. Once the head is reassembled, you can measure the clearance on each valve, calculate the required shim thickness and just order what you need. I assume your mechanic is using the recommended clearances that came with the new cams? I know when I put in my cams from Mark, the required clearances were tighter than the stock cams.
Kirk

[vandor]

If you can get the proper clearance with available valve shims (up to 5.20mm), then use those. If you still have too much clearance then use the tophat shims that go between the valve and the bucket. We carry them. Do not use ones from the Alfa Spiders, as their valves are 1mm larger than Fiat valves. The ones we have are from a Euro-only Alfa engine.

[engineerted]

There is a third option: Do no use the std cam box gasket, make your own from thinner material. Forth option: re- cut the valve seat to drop the valves deeper.