Spencer1 Posted February 18, 2020 Report Share Posted February 18, 2020 Dear all Unfortunately I had to disassemble my engine due to a huge oil consumption. Reason was a totally worne liner. In the workshop we saw that we had to go for 0,60 oversize. I got now new pistons in 0,60. But not originals. The ones I got are from Federal Mogul, very basic pistons, 37P for engines 218 and 230 ci My question: The original pistons have, as far as I know, a play of 0,0030 to 0,00374 inches. The minimal Play for the new FM Pistons is, following Federal Mogul, 0.015 inch. see attached picture. This is extreme small. Does anyone know, by experience, which is the best Play for liner and piston for this engine? Its important for the reboring of the liner. Many thanks in advance and best regards, Michael Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted February 18, 2020 Report Share Posted February 18, 2020 I believe the very specs are base upon the very design of the replacement piston and the very much improved metallurgy. I think a quick note to Federal Mogul will I am sure get all the answers needed and the factors pushing those specs. This would be my starting point. Quote Link to comment Share on other sites More sharing options...
Spencer1 Posted February 18, 2020 Author Report Share Posted February 18, 2020 I am pretty sure that you are right. But the clearance of only 0,0015 sounds very strange I will try to contact them Quote Link to comment Share on other sites More sharing options...
kencombs Posted February 19, 2020 Report Share Posted February 19, 2020 As noted by the first response, Clearance is determined by the piston design and material and can change from maker to maker, even in the same engine. This was copied from the Wiseco web page: Cast pistons with an integral expansion strut were commonplace for many years and they still provide very reliable service in low-power, low-rpm situations. Close to a century ago, the addition of 12 percent silicon as an alloying constituent was found to significantly stabilize the expansion of aluminum components, such as pistons. Known as eutectic-aluminum-silicon alloy, it permitted the development of cast, high-silicon pistons with up to 20 percent silicon alloy. These are known as hypereutectic pistons and their chief advantage is a very low expansion rate. They can be installed with as little as 0.0005-inch piston-to-wall clearance on the major diameter. Note the last sentence. Quote Link to comment Share on other sites More sharing options...
lostviking Posted March 10, 2020 Report Share Posted March 10, 2020 That says the minimum clearance is .0015. It doesn't say the maximum. LV Quote Link to comment Share on other sites More sharing options...
Frank Elder Posted March 11, 2020 Report Share Posted March 11, 2020 I get the piston part.....what is a liner? Quote Link to comment Share on other sites More sharing options...
cavisco1 Posted March 11, 2020 Report Share Posted March 11, 2020 Frank, The original poster is refering to the cylinder bore when referencing liner. The original poster is from Germany where wet or dry liners are common on diesel engines. English is probably his second language. I've seen this reference to cylinders as liners from northern Europeans on several forums. I have been told that English as a second language can be rather difficult, so I typically just overlook these small differences in diction. Take care, Scott. 1 Quote Link to comment Share on other sites More sharing options...
Frank Elder Posted March 14, 2020 Report Share Posted March 14, 2020 @cavisco1 Danke, das ist gut mein Herr! Quote Link to comment Share on other sites More sharing options...
cavisco1 Posted March 16, 2020 Report Share Posted March 16, 2020 Touche sir! My hat is off to you. Quote Link to comment Share on other sites More sharing options...
Spencer1 Posted March 16, 2020 Author Report Share Posted March 16, 2020 Yes Gentlemen, I am from Germany and my English is .... Tomorrow I will get the engine back from the workshop. Halleluja! We decided to go for a cold play of 0,045 mm or 0.0018 inch for piston and bore. This is very few in comparision to modern engines. But the original pistons are fitted with nearly 0 play, only by 6 pounds of force to pass through the bore. Explanation may be that the specific power of the engine is very low and the inner cooling by fat mixture is high. So I dont expect major troubles. I will keep you informed Best Regards and stay healthy. Quote Link to comment Share on other sites More sharing options...
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