GM marine 3.0L (Mercruiser)

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rmyauck
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GM marine 3.0L (Mercruiser)

Post by rmyauck » Mon Aug 07, 2017 4:31 pm

Hi,

Does anyone know if the 1987 head from my 3.0L (has dished D shaped pistons) will work on a similar year 3.0L rebuilt .060 short block (it also has a 2 piece rear seal and my flywheel will bolt up) I found that has flattop pistons (the owner said it had those) or will the compression ratio be too high? Maybe some companies did that for a performance increase.

Maybe also worth the possible HP increase as premium pump gas could be used with no problem.

I see a site showing 2 part # s for their replacement quicksilver heads, with one for 1963-94 and the other for 1990 and up having a different part #

Truckedup
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Re: GM marine 3.0L (Mercruiser)

Post by Truckedup » Wed Aug 09, 2017 6:19 am

You will have to find out the combustion chamber volumes on both heads and the volume of the dish in the piston....But likely if the dished piston compression allows 87 octane gas, then 91 octane should be ok with the flat top pistons...
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