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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: 372444" data-attributes="member: 15774"><p>I think it was a 3/8" end mill that I used on the V-4's. It was a long reach to square off the exhaust ports and they did not make an end mill long enough in 1/4". </p><p> I do not want to change the port timing on my 25hp. If I did change it, It would be to match up to the 30hp specs. It seems that the 25hp block cannot take advantage of the larger carbs. There must be some flow restrictions that can be opened up. </p><p>Has anyone checked compression on these motors? What is good compression on these? The V-4's and 3 cylinders that I have built would be in the 140 to 150 psi range. After porting I will rework the head to bring the compression up.</p></blockquote><p></p>
[QUOTE="Edstrossner, post: 372444, member: 15774"] I think it was a 3/8" end mill that I used on the V-4's. It was a long reach to square off the exhaust ports and they did not make an end mill long enough in 1/4". I do not want to change the port timing on my 25hp. If I did change it, It would be to match up to the 30hp specs. It seems that the 25hp block cannot take advantage of the larger carbs. There must be some flow restrictions that can be opened up. Has anyone checked compression on these motors? What is good compression on these? The V-4's and 3 cylinders that I have built would be in the 140 to 150 psi range. After porting I will rework the head to bring the compression up. [/QUOTE]
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1980's Johnson/Evinrude 20/25hp conversion to 30hp with pics
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