All The Merc Experts

[River Rat 01]

I have a 1970 65hp, can I increase the length from 2.300 inches to 2.562 inches. Or should I keep looking for an 80/85hp powerhead? Thanks,<br /><br /> RR01

 

[kev_79]

Re: All The Merc Experts

length of what?

 

[ODDD1]

Re: All The Merc Experts

Rat, if yer thinkin about a crankshaft/stroke change, pick up a cresent wrench an whack yerself between the eyes...is cheaper, easier an less painful than what yer thinkin about......

 

[River Rat 01]

Re: All The Merc Experts

Thanks ODD 1, that's what I wanted to know. Also the reply I thought I would get. I've got a line on an 80 horse powerhead locally. And you just made my mind up for me. happy boating,<br /><br /> RR01<br /><br /><br />

 

[Chinewalker]

Re: All The Merc Experts

Hi Rat,<br /> I don't think the 80hp powerhead will interchange with the 65hp powerhead - different bolt pattern at the base. The 65 was kind of an oddball motor for Mercury as they liked to do things modularly. The 80hp was basically two 40s one on top of the other. The 90/115 was three 40s, and so on. The 50hp was two 20s. The 65hp 4 cyl. didn't have any other counterparts - maybe that's why they went to the 3-cylinder 65 in '75 (half the 115).<br /> In any case, I'd look for a complete 80hp.<br />- Scott

 

[River Rat 01]

Re: All The Merc Experts

Thanks, Chinewalker, I'll do some more searching on that. I do know that the lower unit is not the one the factory put on it new. It has a larger capacity, and a different gear ratio. Happy Boating<br /><br /> RR01

 

[corm]

Re: All The Merc Experts

the 4 cyl 65 was 2/3s of the 100 hp. in the early 60s.<br />...have fun...corm

 

[River Rat 01]

Re: All The Merc Experts

Thanks all, does anyone know if I can put bigger carbs on it? Happy Boating,<br /><br /> RR01

 

[Rex]

Re: All The Merc Experts

I GOT A 1965 65HP AND 1968 80HP AND THE BOLT<br />PATTERN IS THE SAME. THEY ARE BIG LOWER UNITS. I GOT A 1973 50 HP AND THE LOWER UNIT IS SMALL. IT THINK THE LOWER UNIT OF THE 65 AND THE 80 WILL CHANGE.<br />TYO CAN PUT BIGGER CARB. BUT YOU WILL LOSS<br />YOUR LOW END POWER.<br />REX

 

[Rex]

Re: All The Merc Experts

Could some one help with years of this engine?<br />1).3148587 80 hp. RED AND BLACK.<br />2).2018392 65 hp. SILVER AND BLACK.<br />3).3012531 50 HP. RED AND BLACK.<br />THANK YOU<br />REX A. HUBBLE