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Evinrude 70 CrankPiston Opinions

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oldlugnut

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"I have a 1983 Evinrude 70 wit

"I have a 1983 Evinrude 70 with a bad #3 big end rod bearing that scarred the crank journal. I got a deal on a machined crankcase, new Wiseco pistons, gasket set, and a good used crank & rods. However the crank is the older cast version -- should I be concerned about using the cast crank? The motor goes on a small 15" runabout & I don't intend to run it hard. Did the cast cranks have a high failure rate in those early motors? Isn't there a thicker head gasket available to drop compression slightly? If so, might that reduce the stress on the crank a little? Also, the crankcase & pistons are 20/40/20 oversize. Should the 40-over cause me concern? This crank/bore/forged piston combination certainly wouldn't be my preference, but it wasn't a lot of money. I'm familiar with older 2-stroke motorcycle engines but I just don't have any experience with outboard motors & would like some opinions on the cast crank & large overbore on #2. Should I use the cast crank for an anchor and spring for a rebuilt forged unit? Or throw it together as is & never leave home without a kicker motor??"
 
"build it up!--there was some

"build it up!--there was some bulletins on cranks of that yr,..but i cant rem what it was...and i'm waaaaay too lazy to dig thru all of it...dont worry about it,dont use the comp lowering hd-gaskets.make sure,u do the carbs,link and sync,and tune up and timing procedures....use a FACTORY service manual...
inst a new water pump kit..."
 
"Thanks, I appreciate your adv

"Thanks, I appreciate your advice. I really didn't want to spend the bucks for another crank, unless absolutely necessary. I plan on following the book exactly on the set up & will also service the bottom end including the water pump. Another question -- the previous owner used 80:1 premix, claiming that anything richer would foul the plugs. Besides the failed bearing I also noticed scuffing on the exhaust side of all the pistons. Isn't 50:1 the recommended mixture on these old motors?"
 
Use 50:1 - and thank the previ

Use 50:1 - and thank the previous owner for your current issues which probably resulted from running at 80:1 especially if the motor spent alot of time near idle speed/trolling...
 
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