Dan Sarandrea (Phila)
Waitin' On Parts...
[Continued from Valve Adjustment Part Two-A: https://xwebforums.com/forum/index.php?threads/valve-adjustment-part-two-a.25497/#post-212035]
Once you get the shim out, you'll see that it is just a metal disc (precision ground and hardened of course) approx. 33mm in diameter. Each shim would have been printed with its thickness, but over time and in use the printing may have worn off.
IMPORTANT! Whenever there is a shim removed from its place on its bucket, DO NOT under any circumstances allow the engine and cam to rotate! Cam rotation without shims may cause the cam to crash into the edges of the bucket, which could ruin the cam, the bucket, or both.
So now that your shim has been removed, note and record its thickness.
Here's what mine were (in mm):
Cyl Exist clearance Exist shim
4E .330 3.92
4I .178 4.07
3I .280 3.92
3E .372 3.72
2E .356 3.97
2I .229 4.10
1I .203 3.90
1E .256 3.90
In some cases, the shim that you remove will not have its thickness printed on it, or whatever was printed on it in the past has worn off. To accurately determine the thickness of the shim in these cases, you'll need either a micrometer or a digital caliper. For the average home mechanic, IMO the more practical option is to purchase an inexpensive digital caliper. For example:
(a) Very inexpensive item from Harbor Freight: http://www.harborfreight.com/4-inch-digital-caliper-47256.html
(b) Higher end, name brand item: http://www.ebay.com/itm/251621340889
Measuring is easy!
1. Close the caliper jaws
2. Zero the reading, then set the scale for mm rather than inches
3. Open the jaws, insert disc, then close jaws
4. Record thickness reading. Note that OEM FIAT shims come in 0.05mm increments in the range of 3.25 thru 4.70. Aftermarket suppliers also provide shims kits to service shops; in order to offer a finer-tuned level of adjustment, often these kits will include shims that measure to x.x2 or x.x7 increments, along with the standard increment of x.x5. If your car has had its valves adjusted, and you are measuring values ending in x.x2 or x.x7, it's possible it was fitted with aftermarket shims.
5. If your measurements are yielding odd sizes, you may be measuring a very worn shim, or your calipers may not be "up to the task." See if you can borrow a different set from a friend.
5. Note that the overall diameter of shims should be a nominal 33mm. DO NOT use shims that measure about 31mm, these are for other European makes and use of these shims will most likely grenade your cylinder head.
In the final part, Part Three, http://xwebforums.com/forum/index.php?threads/25531/, we'll calculate the replacement shims needed and install.
Once you get the shim out, you'll see that it is just a metal disc (precision ground and hardened of course) approx. 33mm in diameter. Each shim would have been printed with its thickness, but over time and in use the printing may have worn off.
IMPORTANT! Whenever there is a shim removed from its place on its bucket, DO NOT under any circumstances allow the engine and cam to rotate! Cam rotation without shims may cause the cam to crash into the edges of the bucket, which could ruin the cam, the bucket, or both.
So now that your shim has been removed, note and record its thickness.
Here's what mine were (in mm):
Cyl Exist clearance Exist shim
4E .330 3.92
4I .178 4.07
3I .280 3.92
3E .372 3.72
2E .356 3.97
2I .229 4.10
1I .203 3.90
1E .256 3.90
In some cases, the shim that you remove will not have its thickness printed on it, or whatever was printed on it in the past has worn off. To accurately determine the thickness of the shim in these cases, you'll need either a micrometer or a digital caliper. For the average home mechanic, IMO the more practical option is to purchase an inexpensive digital caliper. For example:
(a) Very inexpensive item from Harbor Freight: http://www.harborfreight.com/4-inch-digital-caliper-47256.html
(b) Higher end, name brand item: http://www.ebay.com/itm/251621340889
Measuring is easy!
1. Close the caliper jaws
2. Zero the reading, then set the scale for mm rather than inches
3. Open the jaws, insert disc, then close jaws
4. Record thickness reading. Note that OEM FIAT shims come in 0.05mm increments in the range of 3.25 thru 4.70. Aftermarket suppliers also provide shims kits to service shops; in order to offer a finer-tuned level of adjustment, often these kits will include shims that measure to x.x2 or x.x7 increments, along with the standard increment of x.x5. If your car has had its valves adjusted, and you are measuring values ending in x.x2 or x.x7, it's possible it was fitted with aftermarket shims.
5. If your measurements are yielding odd sizes, you may be measuring a very worn shim, or your calipers may not be "up to the task." See if you can borrow a different set from a friend.
5. Note that the overall diameter of shims should be a nominal 33mm. DO NOT use shims that measure about 31mm, these are for other European makes and use of these shims will most likely grenade your cylinder head.
In the final part, Part Three, http://xwebforums.com/forum/index.php?threads/25531/, we'll calculate the replacement shims needed and install.
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