1981 150hp Evinrude Connecting rods

[irdir]

I bought the engine on eBay for a good deal. It came apart because it had scored walls but was already repaired and ready to go back together. However, I noticed that 3 of the connecting rods had been grinded down on the sides to remove the lip. I just wanted to know maybe why they were grounded down or if it’s even still usable. Should I get new connecting rods?

 

[Walker]

Re: 1981 150hp Evinrude Connecting rods

Don't know why yours were ground down, but on high RPM racing engines they are ground smooth and shot peened and polished, and balanced. The reason is to remove any edges where a crack can start easily. If you have 3 of each then you probably have a balance problem at the least.

 

[Dhadley]

Re: 1981 150hp Evinrude Connecting rods

Some rods in Sea Drives were beam ground. There are at leat 7 different style castings for a crossflow and 6V6 rod. You can mix and match, youll be fine. <br /><br />We've ran those rods at over 7000 rpm, as produced, with no problem.

 

[walleyehed]

Re: 1981 150hp Evinrude Connecting rods

Interesting topic, as I had the same issue a few months back with an '82 200.....5 rods with the rib and 1 without.<br />Ole' walleyehed got the grinder out and finished the other 5, even though they were the same P/N-321712, but as Dhadley says it didn't seem to make a difference BEFORE I ground them...

 

[irdir]

Re: 1981 150hp Evinrude Connecting rods

Thanks guys. I guess I might as well grind the others down just to have some fun.

 

[Bob in Calif.]

Re: 1981 150hp Evinrude Connecting rods

If you have a gram scale, you might want to weigh each rod before you start on grinding them.<br /><br />..Bob in Calif...

 

[walleyehed]

Re: 1981 150hp Evinrude Connecting rods

Be careful grinding....you don't want them to get hot in a localized area..do it slowly with light pressure.<br />And, as for weighing them, it would be neat to get them really close AFTER you grind them...

 

[Dhadley]

Re: 1981 150hp Evinrude Connecting rods

Match the weights end for end not just total weight. <br /><br />Oh -- did I mention there are different length crossflow rods with the same part number? (Now we're really splitting hairs......)

 

[walleyehed]

Re: 1981 150hp Evinrude Connecting rods

Come clean, DH.....I NEED info on that last comment.......please?...the part about "different lengths".... <br />I can't tear-down again...I will steal your 6V6 if you tell me I have to tear-down.<br />OOOOKKKKK.....Now I sceeeerd.<br />I can see it now...I'll start my own forum...<br />CRY-N-SINK

 

[Dhadley]

Re: 1981 150hp Evinrude Connecting rods

LOL !! Too funny.<br /><br />Like I mentioned, we found at least 7 different rods under that part number. Ever noticed the yellow, blue, red or white dots? Or ones with no dots?<br /><br />We made up a jig to measure them and there is a difference. Most are within about .005". There are some, and they are quite rare, that weigh less than the others and are slightly longer. <br /><br />The bottom line? We never saw a motor run any different with any rod. Just one of those things that falls within a spec and makes no difference.<br /><br />No need to tear down. And no need to steal my 6V6. Well, OK -- they are stronger than a crossflow. Better go put a chain on it...

 

[walleyehed]

Re: 1981 150hp Evinrude Connecting rods

May all birds fly upside-down next time you wash your car, DH... <br />If these are all ok, I guess you can forget the chain.........for now.

 

[Dhadley]

Re: 1981 150hp Evinrude Connecting rods

Whew!!