Resurfacing head

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BomberModelA

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1984 johnson 15. Purchased boat, motor was given to me, rebuilt carb, fuel pump and water pump. Had good flow after impellor change. Motor ran hot after 10 minutes on maiden voyage would not restart. Checked compression 30 psi top 70 bottom. Tore into motor head bolts were loose caking around top cylinder, blocked passage ways and no thermostat (arghh). Pistons and cylinder walls have no scrapes, rings were free but I am replacing them. Took Rick's advice and used sheet of glass with 600 grit wet sanding in figure 8 have used 3 sheets. My question does the mating surface have to be completely shiny?

Side note how clean does top of piston and head need to be have used sea-foam, carb chem-dip and soft bristle brass brush but still some carbon showing. I do have aluminum compund and buffing wheel but don't want to do anything that is not needed or would mess up things.
 

194269

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Re: Resurfacing head

The whole head should be shiny, some carbon is normal. If you think there to much, run some sea foam through it after the new head gasket has been installed.
 

wilde1j

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Re: Resurfacing head

Shiny is NOT the objective, FLAT is. If the head is flat, the surface will have a uniform appearance.
 

BomberModelA

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Re: Resurfacing head

More sanding seems to be in order. Can I go with a heavier grit then use 600.
 

retiredfornow

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Re: Resurfacing head

Heavier grit till you get a uniform look, then work your way back to 600. Good luck, it's a boring job.
 

wilde1j

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Re: Resurfacing head

I have never used anything finer than 200. No wonder you're using so many sheets. 150 to 200 is fine.
 

gordwa

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Re: Resurfacing head

Did you check it with a good straight edge using a feeler gauge to measure the how much warpage you have??? It might be warped so bad it will never seal right for you.
 

BomberModelA

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Re: Resurfacing head

I'll check that too. Do you go diagonally? I used to have all my V-8 heads resurfaced at the machine shop when they ground the valves. This is my first outboard project got to start somewhere. Thanks for all the help.
 

Maraian

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How warped is too warped of a head? I'm about to start sanding a 2006 J 15 and wondering if I might as well just buy a new head but would like to save a few $$ if I can?
 

flyingscott

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Racerone has a great solution for resurfacing a head take valve grinding compound and spread it out on the glass and surface with that
 

GA_Boater

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How warped is too warped of a head? I'm about to start sanding a 2006 J 15 and wondering if I might as well just buy a new head but would like to save a few $$ if I can?



This should be in a new thread.

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