1979 Evinrude 85hp std bore dia

[wannabewelder]

Hi Guys, I have to bore an 85hp, 1979 head 0.020" does anybody have the std bore dia? I was only able to locate a 1976 manual which is different bore. My block is 3.490" at the top, the donor block is 3.514-3.516" and stamped 0.020" over.
A friend gave me a deal on the donor but the bolt pattern on the base is off so I think it is a 1976ish. I think they rebuilt it and swapped rods and 2 ring pistons that are newer. The rods are correct and pistons measure up.
The 1976 FSMl lists std bore @ 3.475".

 

[racerone]

Time for some facts.----The 76 bore is standard at 3.375 ?----The 79 bore is 3.500 when it left the factory.------Nothing else !-----Perhaps calibrate / check your measuring tools too.

 

[jimmbo]

The 85 used a 3.375" bore from 1969 thru 1978, in 79 the bore was increased to 3.500". There is no way to increase the bore 0.125" and expect it to survive

 

[wannabewelder]

Something is fishy then because my donor block has the old style base gasket and won't bolt up. That's why I'm doing the piston swap. The pistons in the '79 seem to have alot of slop for the bore dia. being "close"
Thanks for the info.