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1980's Johnson/Evinrude 20/25hp conversion to 30hp with pics
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<blockquote data-quote="Edstrossner" data-source="post: 374079" data-attributes="member: 15774"><p>I measured the piston dome at .625 from the deck to the dome at TDC.</p><p>The head measures .650. The gasket adds .050 so at TDC the dome to head squish clearance is at .075.</p><p>I like to run a squish clearance at .030 to .035. </p><p>So from a stock head you can mill .040 off the head without any additional milling inside the combustion chamber.</p><p>These numbers are from my 2000 Johnson 25hp.</p><p>I did a lot more work on my head to bring the compression up to 145 psi .</p><p></p><p>I don't know first hand about the 1982 head. I would love to see one.</p></blockquote><p></p>
[QUOTE="Edstrossner, post: 374079, member: 15774"] I measured the piston dome at .625 from the deck to the dome at TDC. The head measures .650. The gasket adds .050 so at TDC the dome to head squish clearance is at .075. I like to run a squish clearance at .030 to .035. So from a stock head you can mill .040 off the head without any additional milling inside the combustion chamber. These numbers are from my 2000 Johnson 25hp. I did a lot more work on my head to bring the compression up to 145 psi . I don't know first hand about the 1982 head. I would love to see one. [/QUOTE]
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1980's Johnson/Evinrude 20/25hp conversion to 30hp with pics
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