Cam lobe shim specs

[njoconnor]

Since I had to remove the cam box covers to prep for new gaskets, I decided to check the gap between the cam lobes and the valve shims. My first surprise was that my feeler gauge set (a Craftsman set, about 40 years old, purchased to gap our Maverick's points) lacked a .17 and a .19 feeler (.5 and .45mm per factory manual). Made my chart, slipped a 1.5 inch socket and long rachet onto the crankshaft pulley nut, and proceeded to walk the engine around and check the gaps. Results were interesting:
Cyl: 1 2 3 4
EXH: .41/.016 .41/.016 .46/.018 .46/.018 (mm/in)

INT: .38/.015 .38/.015 .41/.016 .38/.015

Brad's book lists a range of .016-.019 in for intake, .018-.021 for the exhaust. Engine was definitely cold: last start up was December. Engine has about 2500 miles on it since its 2011 rebuild, by a mechanic in rural Brodhead (not a Fiat or foriegn car specialist) for the PO. Most of the miles were run up last summer/fall. I've always run zinc additive in the car since I bought it.

Obviously, I'm a little tight on both sides. Does this result warrant a shim change? With additional miles on the car, will the gaps open up closer to spec? Is there a generally accepted "index shim thickness" (a specific shim width which would, in most cars, give you the specified gap), from which one could calculate the shims necessary to reach spec?

I'm planning an order to A/R in the next week or so, and if it's a good idea to order different shims, I'd like to place one order (need the shim tool as well... ). Any thoughts appreciated.

Neil

[azruss]

As the cam tower gasket compresses, the gap will actually get tighter, so if you are below minimum now, it will not get better with age. There is no "master" shim. You need to "mic" each shim and calculate what thickness you need to get each one into tolerance.

[njoconnor]

Thanks! 'Fraid that was the answer on the master or zero shim. I was hoping to avoid two sets of shipping costs, but, heck, eight shims can't weigh THAT much!

So, off to order stuff, including the famous tool, and get these things into spec.

Neil

[vandor]

This is why it's important to write down the shim sizes in each location when the head is rebuilt, so one can do the next adjustment in one step.

[njoconnor]

Yup, Csaba, did that. Nice little chart on a 3x5 card, by cylinder, engine side. Once I remove and ID each of the existing shims, just a matter of some addition/subtraction, and the shim order is outbound! But, I need the cam bucket tool, and the gaskets, and, and,.....

Be talking to you guys in a few days.

Neil

[KevAndAndi]

I haven't yet checked my valve shims, but when I do, I plan to try this approach:

http://fiatspider.com/f15/viewtopic.php ... al#p236145

Sounds cheap and easy to me. Has anyone tried it besides the original author (Jon124)?