Rebuilding Good Old Fashioned Chevrolet Motors – Measuring Piston Clearance & Clearances

When working on and rebuilding classic vintage good old fashioned American made Chevy engines a question often comes up of measuring engine “piston clearance”.

One method of measuring this piston is to use one-half inch wide feeler gauge stock. Such a feeler gauge of the desired width and thickness can be secured in lengths of approximately 12 in. long. The procedure is basically to place the feeler gauge along the side of the piston 90 degrees around the piston from the piston ring. The piston and feeler gauge are now into the actual cylinder bore.

If the clearance can be considered by the mechanic or technician involved in the engine testing or rebuilding renewal process the piston can be said or is basically termed or described to push the cylinder with “light pressure”. However on the other hand it should “lock” if a feeler gauge of 0.001 inches more than standard clearance is used. Another or alternate method is “pull” required to pull the feeler gauge from between the piston and cylinder wall. The puller gauge should be pulled up and out by means of a scale. This reading or the readings should be in most likelihood being in the ranges of between 7 and 18 lb measurements. If less than that amount, the clearance can be termed all in all to be excessive and if more than amount the clearance is insufficient.

Still what might be called another or alternate method of measuring this piston clearance is to use micrometers. In this case and these cases the diameter of the cylinder bore is taken and measured with “inside micrometers”, and the diameter of the pistons is measured with “outside micrometers”. Experienced mechanics in the engine rebuild fields will advise with the voice of many auto engine rebuilds under their belts , that when taking to measuring the cylinder bore and bores take to measure it across the width of the engine and the diameter and diameters of the engine is thus measured across the thrust faces. The difference between the two diameters will thus be and is essentially this “piston clearance”.

Lastly it should be noted that if the clearance and clearances overall are in excess of the amount specified, the pistons should be expanded sufficiently to obtain the desired clearance and engine tolerance clearances. Your local automotive machine shop should have the necessary and essential hardware and equipment of expanding these pistons.

It might be said that these methods for rebuilding older and vintage Chevy engines are “old fashioned “as they do involve hand and mechanical measurement rather than all of the new fangled electronic and electronic gizmos available on the automotive repair and aftermarket auto parts markets.

True there may be fancier ways and means to accomplish these tasks – some might be considered more up to date modern and even easier and ultimately more precise. Yet vintage automobile experts and enthusiasts will swear to you that nothing but nothing beats the satisfaction of working on an older, old fashioned good old American made Chevy engine with elbow grease itself.

Author Bio: Kerry A. Francis Auto Sales Vancouver BC Langley British Columbia Premium Used Cars Online Automotive Dealers in Surrey Canada

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