Mercury Rod Cap Alignment

[rock]

Post the number on the rod and I will see if I have a used one.

Rock

[pbxcomm]

Rock,
Mercury P/N : 646-818846T6.. I checked and seems they are not superseded..

Thanks again..

-Marc

[FORBESAUTO]

Pro marine offers an aftermarket rod for $89.84. Don't know much about them except they are made in Japan. I put a 141 series one in a 150 and haven't had any issues. It actually had the oil grooves in it and weighed more than the oem ones without the groove. Not sure if that's a good thing or not, but made me feel it was more dense.

[FORBESAUTO]

The part number is 646N

[Onetime]

He says it's a Merc 90 HP not OMC.

Play with checkng part numbers for different models and seeing what other engines it fits. Might just interchange with something that you can easily find a good used one.

[FORBESAUTO]

That is the part number for his motor using the part number he provided

[Jay Smith]

Oops thought it was an OMC ....

Jay

[StratosVT]

Rock,
Mercury P/N : 646-818846T6.. I checked and seems they are not superseded..
Thanks again..
-Marc

Go to Ebay and type in 646-818846 or just 818846. You'll find a plenty of used & new rods to choose from.

[Jay Smith]

Small trick I was taught by one of the BEST Mercury Master Techs on the planet ( Chris Justice ) after you get a perfect internal cracked cap fit use a 400 grit ball hone on both small and big end of bearing surfaces , just about 20 turns to the left and 20 turns to right cross hatching in and out with honeing oil ... Been using Chris's trick for 20 years on an average to 75 - 100 motors a year and I can NEVER remember a rod bearing surface failure ...

Jay

[Jay Smith]

BTW Chris Justice goes by half - fast on Scream and Fly and owns Justice Marine in Eataton , Ga. if your near his dealership and need to buy new or repair he's da best ..

Jay

[Chaz]

Chaz = remember thinkin a Rubik's cube algorithm's were tough to line up ...

While being able to flow and store an oil wedge in the RVK ( valley of honed surface) is essential , I think survival of the crank and/or rod has more to do with how well the parts were carburized ( heat treat process) during manufacture .
While I don't R+R 100 motors a year , I do run across some stuff that peeled for no apparent reason .. so yes , it's nicer to have friends that work at makin part's for the little model rocket club , up the street . They can put their finger on why that happens . More times than not the Rockwell was way high and very shallow .

My finger's is way too old ta "hone" rod ends with sandpaper ...

[rock]

Pbx Check your pm.

Rock

[Capt.Insane-o]

Pro marine offers an aftermarket rod for $89.84. Don't know much about them except they are made in Japan. I put a 141 series one in a 150 and haven't had any issues. It actually had the oil grooves in it and weighed more than the oem ones without the groove. Not sure if that's a good thing or not, but made me feel it was more dense.

I've used quite a few of those rods with no issues.

[pbxcomm]

Hi all.. Good read..
For what its worth, I use the middle (flat) portion of my index finger with crocus cloth on the crank end and 320 on the wrist pin end, I can make a nice cross hatch (from practice).. I think the 400 ball hone is a consideration, now that I have a spare (junk) rod, I'll try the ball hone idea.
I did bite the bullet so to speak with a purchase of a brand new rod @ $232.00. I replaced only one out of three as the others where seemingly perfect and I realize that a "good" rod is subjective (my girlfriend agreed, although didn't quite grasp the intended pun). I didn't want to take a chance with a used (subjective) rod, I've replaced all bearings, seals, jackets, covers, pistons/rings, so I think the new rod was warranted here.
Thanks to all the offers!
The other two rods I checked both externally and internally.. Turns out internally they were perfectly aligned, externally, not so much. So, what I did was aligned the caps, torqued the bolts, fired up my dremmel scribe and got going on new scribe marks on the surface and both sides. I know now when I align the new scribe marks, the internal surface will be perfect.. Which brings me to my next question.. How many of you out there re-use rod bolts? We never did on the in line 6's, but this theory or rule seems no to be specific to the larger rod bolts like on the 90's. I'm not re-using the rod bolts (purchased new OEM's) just curious.

Thanks again to all!

[Capt.Insane-o]

Never ever ever ever re use torque to yield rod bolts. The SPS or ARP bolts in the hi perf motors are a different story.