Fitting Chevrolet Piston Rings
This article is only for Chevy Antique cars
Properly fitting each piston ring
Too much stress cannot be laid upon the importance of properly fitting each piston ring. It is safe to say that very few consider it important, and as a result loss of power—badly carbonized valves and pistons and other cylinder troubles, result.
The purpose of a piston ring is to fill up the space between the cylinder walls and the piston, so as to prevent leakage of gases and oil.
As these gases are under considerable pressure, it is therefore necessary that the rings not only fit snugly around the cylinder walls, but in the grooves of the pistons as well, otherwise the gases and oil work behind the rings.
To properly fit new piston rings, proceed as follows:
Slip the ring into the cylinder, pressing it down about half way into the bore. See that the ring is square with the cylinder walls; that is, its plane should be at right angles to its axis.
Secure a narrow strip of brass or steel three one-thousandths of an inch thick and slip it between the two edges of the split in the ring. Make sure that the ring is resting in the cylinder in the same position that it would were it in the piston, then withdraw the gauge.
For a properly fitted ring, there should be a slight resistance, that is, you should feel the edges of the ring drag on the gauge.
If the space between the splits is less than this, remove the ring and with a very fine file dress the edge until proper clearance is obtained. Be careful not to round the edges of the ring—keep the file flat. Fit each ring separately.
With a scraping tool carefully remove all particles of carbon from the faces of the ring grooves in the piston.
Slip the back side of the ring into the groove and roll it entirely around the groove. If the ring is the proper thickness you should feel it drag slightly in the groove. If it is too loose, try another ring.
If too thick fasten the ring to a flat board then lay a sheet of very fine emery cloth on a surface plate. Lay the board, ring down, on the emery cloth and with the hand resting lightly on the board slide it across the emery.
Be careful to put pressure on the board evenly, so as to remove an equal amount of metal from the entire surface of the ring.Remove the ring from the board and try the fit, repeating the grinding operation if necessary.
Slip the rings into their grooves, starting with the lower ring.Be very careful not to injure the edges of the ring, as these must not be broken in any way, otherwise trouble will result.
In slipping the pistons back into the cylinders use extreme care take your time and do not force the rings into the bore. Compress the rings with the fingers until they enter the cylinder easily.
The splits in the three rings should not be in a vertical line, as the gases could leak by more easily. Therefore stagger the splits so that they will be equally distant around the circumference of the piston.
Fitting Piston Pins
To determine if the piston pins are worn, clamp the connecting rod in a vise the same as in fitting piston rings. Take the piston in both hands and move it upward and downward and if there is any wear, it can easily be detected. If a standard size piston pin is too small an,oversize pin can be installed.
Piston pins should be fitted so that the piston will rock on the pin with a slight amount of pressure being exerted with the hand. Piston pins fitted too tightly are likely to “freeze” and score the piston.
When reaming piston pin holes in the piston, care should be exercised not to allow the reamer to “chatter” as the hole should be perfectly smooth. A very good reamer for this purpose is a is” expansion reamer.
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Fitting Chevrolet Piston Rings Article Source : This article courtesy should goes to : Chevrolet Repair Guide of 1923 by Chevrolet Motor Company.