Cam bearigns - how to check for in/out spec?

[Johnfm]

From the thread on my compression numbers, I posted the valve clearances - and #1 inlet and exhaust have clearance lower than spec.

Another poster mentions "I might need new cam bearings".

How do I rule that in or out? No point just re-shimming the out of spec valves if the bearings are out of spec.

[promotor]

You need to accurately check the size of the bearing of the camshaft itself with a micrometer to make sure that is in spec, then use Plastigauge (it's a gauging material made of something similar to - but not the same as - plasticene) between the bearings and camshaft with the cam caps tightened to their normal torque.

The amount it squashes tells you how much clearance there is. There are different ranges of Plastigauge available depending on the range of clearance you wish to measure. Available on ebay.

[Esprit2]

Use Plastigage. Remove a bearing cap. Cut a strip of Plastigage a little shorter than the width of the bearing, and lay it on top of the cam journal, parallel to the cam's long axis. Replace the bearing cap and torque the bolts to spec.

Remove the bearing cap again, and you'll see that the slender spaghetti noodle you put in there has now been squished out wide and flat. On the Plastigage package you will find a row of different width bars. Put the bars next to the squished strip, and find the bar that most closely matches it's width. Printed on that matching bar you will find the clearance.

Repeat for each bearing. Put a squirt of oil on each cam journal before re-installing the bearing cap for the final time.

Plastigage is available from better auto parts stores (motor factors) "everywhere". It comes in several sizes for different clearance ranges. It's cheap, so I recommend you just pick up one of each. Failing that, write down the bearing's spec clearance range and take it with you. Buy one package for clearance range you need, and one package for the next wider/ loser range (ie, if the bearings are worn, the clearance will be larger).

Regards,
Tim Engel