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What year powerheads will interchange for a 70HP?

J

jn1440

Contributing Member
Hello everyone,

Looking for some help determining what year powerheads I can use on a 1984 evinrude 70. I have done some research already and haven't quite found a definite answer so I thought I would ask.

I know 1979-1984 are a sure thing. But I happen to stumble across a 1987 with a good powerhead. Blocks are different part number but the crankshafts are the same number. From pictures it looks like the linkages for throttle and shifting are the same or close enough as well as how the stator and timing base mount. The starters are the same so I imagine the flywheel is the same as well? The four concerns I haven't been able to find answers to are how the block fits to the midsection, the fuel pump, carburetors and mounting the electronics (coils, powerpack rectifier etc).

Thanks guys I appreciate any input!
 
You will need the 87 adaptor plate to go with the 87 block I believe the exhaust tuning is different. Your block is a 49 cid block the 87 block is a 56 cid so thats where they are different. If the 87 is complete and sounds like it just needs a lower unit. Your lower unit will bolt right up to it with no modifications and you will end up with a much more powerful motor. As far as ignition and coils everything bolts up the same way. The carbs will not interchange there are changes there. 1979-1985 will interchange.
 
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Unfortunately the midsection is being parted out separately to get the trim tilt unit off of, the electronics on it are iffy the ones on my engine are all pretty much brand new. Doesn't sound like it will work out just have to keep looking for a 1979-85 powerhead. Anyone have one for sale? Haha. Thanks for your help!
 
The only real difference is the mounting bolts....the 56ci use a 3/8 and the 49ci uses 5/16. See several 49ci on 56ci mid's that run fine
 
The 49 CI blocks and 56 CI blocks use a different base gasket.-------Some later 49 CI blocks use the 3/8" bolts.
 
Yeah I'm pretty sure it's the 5/16" bolts. Would you need to oversize the midsection bolt holes? Cant remember how much room was around the bolts. That leaves the only thing missing to be a set of carburetors.
 
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