How to Modify Your Nissan & Datsun OHC Engine by Frank Honsowetz

Author:Frank Honsowetz [Honsowetz, Frank]
Language: eng
Format: azw3
Publisher: California Bill's Automotive Handbooks
Published: 2004-04-29T04:00:00+00:00

Micrometers and dial bore gage are ideal for checking cylinder- and bearing-bore sizes and clearances.

Telescoping gage and micrometer can also be used to check connecting-rod big end. Tom Monroe photo.

If you are using full-floating piston pins with Teflon buttons at the ends, measure the overall length of the pin-and-button assembly. This measurement should be 0.015—0.017-in. less than the bore diameter to provide sufficient pin-to-bore clearance. If the pin-and-button assembly is too short, get new buttons. But if the assembly is slightly too long—about 0.002 in. you can machine the buttons to make them shorter, providing you maintain the original contour. Pin-and-button assemblies that are substantially longer should be corrected with new buttons.

If beveled-type circlips or Spirolox-type retaining rings are used, install a ring in one groove only in each piston-pin bore. Install the circlip so the rounded edge will be against the pin. This will put the sharp, square edge out, away from the direction of pin thrust.

Insert the pin in the other end of the pin bore, hold it against the retaining ring, and check the distance from the end of the pin to the edge of the empty retaining-ring groove. A 0—0.001-in. clearance is desirable. This will keep the pin from being preloaded against the retainers and possibly popping them out of their grooves.

After checking and recording the results, remove the piston pin. Leave the retainer in place. Keep each pin with its matching piston as a set for final assembly. Next, check the fit of the pin in the small end of the respective connecting rod. Pin-to-bore clearance should be 0.0008—0.0011 in.

CAUTION: Never reuse Spirolox type retaining rings. Instead, replace them.

CONNECTING-ROD BEARINGS

To select the correct rod bearings, start by checking the size of the big end of each rod. If the bore in which a bearing is to be installed isn’t the correct size or true, bearing fit or crush will not be correct. So, if you haven’t checked the big ends for size and trueness, do so now.

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