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Thanks Jaymz for the info! I understand the 5 codes stamped on the crank is for the 5 main journals and the four letters (AAAA) crank bore code. The 5 crank bore codes also stamp on the engine block? They are suppose to be the same correct? It is confusing cause your info mention CCCCC and on the crank is 11111.
5 letters on the block are used with the 5 numbers from the crank. There are 2 bearings per journal. If you look at the reference chart some combinations will have 1 color and others will have 2 colors. 1 color means both upper and lower bearing are the same.
The 4 letters on the crank are used with the numbers on the conrods. Same is goes for the colors. 1 color both bearing per journal as the same. 2 colors means different bearing for cap and rod.
Hope that helps.
I am doing a rebuild on an F20C with low mileage block, round, peak, and walls all good to go. Using std 87mm nippin pistons, oem rods, crank and bearings. I sure hope the techs got the no honing right, as I would rather not put everything together just to find out I built an expensive low comrpession oil burner.
Are you trying to run STD Nippon racing pistons on a good condition/undisturbed bore? The Nippon pistons require higher piston to wall clearance initially than the factory original pistons. The required clearance is 0.0013in.
Yes, I am and was not aware they needed higher piston to wall clearance, thank you. Cylinders are running 87.038-39 on thrust side, 87.029-30 on other axis and Pistons are right at or near oem spec. Appears to be too much rather than too little P/W clearance. Do you think this is going to cause problems? Still within service limits, but seems a bit on the loose side of the equation rather than too tight. Also do you have any data sheets, etc that provide more information regarding clearances etc specific to pistons and f20c? After measuring and comparing to oem pistons, there does not seem to be any significant difference in specs, including weight, albeit I did note in one of your posts where you indicated that piston pins did not have coating and will be using oem. Any advise you can offer is appreciated as I have been working off the assumption these pistons are installed according to oem specifications and was not aware there was any information out there to the contrary.
Do you have the exact measurement of the Nippon Racing piston? "right or at near OEM" spec is not enough information. You need the exact measurement and go from there. The reason more clearance is needed is because of differences in materials used. How many miles are on the used block? Why are these pistons being used?
The 0.0013 clearance advice was obtained from the seller directly. The pistons are setup to have the proper clearance when the bores are finished in the proper size: 87.00 and 87.25mm.
At this moment, I have a set of 87.25mm Nippon Racing pistons sitting in my box and I measured them to see if this is true.
The Nippon Racing measured at 3.4337 in. Bear in mind this is below the factory spec for an OEM genuine OS piston (3.4344-3.4349).
If you made the bore exactly 3.4350in (87.25mm), then you have the required 0.0013in.
The same clearance and math applies to the STD 87mm piston.
If you measure the Nippon piston and the factory piston carefully, you will see that the Nippon is smaller diameter; exact measurements are required.
Thank you for information, and after consideration and reading your comments and understanding a little better the advantages disadvantages of nippon vs. oem pistons, decided to go with oem rather than rake a gamble on the nippons....although my wallet is now bruised quite a bit and the only reason I chose nippons was cost savings.
Thank you for taking the time to reply and point me in the right direction. I will post the results after I am done.
07-25-2020, 12:09 PM
