Mercury Rod Cap Alignment

[pbxcomm]

Hello all..
Hoping someone can help me out here..
I haven't rebuilt a powerhead in a while, but in the day I've rebuilt hundreds..
I recently went through my 2000 90HP merc so I can bring it to factory specs. I'm stuck at a certain rod/cap alignment on only one rod.
The other two rods are perfectly matched my finger nail (and an awl) runs smooth across both side surfaces on two rods with the exception of one. One side of one rod seems to be aligned perfectly, the other side (regardless how hard I try) does not seem to be
perfectly matched. Specifically there's a very small area in the middle of the surface that is smooth.. The outside edges of the flat surface however is where I can slightly catch my fingernail. I noticed from the factory that the outside edges are rough (when they cracked the rods) I guess my question is if one side of the rod is perfectly matched and the other would catch my nail if I try very hard, should I worry and try another rod? I've read a few posts that new rods are prone to this as well. Am I being to critical?


Thanks..


Hope to get some sleep tonight.

[FORBESAUTO]

I would get another rod, I don't like using them if I can catch a nail on it. I got a box full of rods I've culled. Don't ask me why I keep em, I guess I'm hoping they'll fix themselves and I can use them one day I don't think you can be too picky in this area

[FORBESAUTO]

Also, make sure your tightening them to proper torque when checking. If your not already doing it. Doing so could make all the difference in passing or failing.

[StratosVT]

Try tightening it off the crank. If the inside part is smooth and the outside lines up the same with the part where you can catch a nail, I'd use it and not worry about it. As long as you know the bearing surface it right, that's all that really matters. My thinking is that that the metal didn't change, it came that way from the factory and assuming its off of a well used motor it should be fine. But I'd check the bearing surface to be sure..jmo

[FORBESAUTO]

The bearing surface is whats important as mentioned. I thought the bearing surface is where your nail was catching, sorry if I read it wrong.

[FMP]

With all those old rods and caps, you could get artistic and weld up a rod monster or maybe a sculpture in the form of an outboard or something.

[Capt.Insane-o]

They make great bottle openers

[FMP]

Table lamps , coat rack hanger mounted to wall, half circle tie holder big end out wall mounted, etc

[Chaz]

All of them have little "cliffs" and "ravines" that fit together . Some need to be 'worked into place" a little bit . Within reason , I think those can actually be better at keeping their contact patch aligned at high RPM , under detonation , etc .

A rod vice , or even a set of soft jaw's for a standard vise make quick work of torqueing and disassembly during mock up .
And if anyone really want to add to the "junk parts pile" invest in a small dial bore gauge ..

I'd give a random cap to one of my friends in the aero forensic lab for analysis . But when we looked at the scoped images and read the report , none of us would ever want to use one of those rods ever again ...

[tux974]

I cut a trashed crank in a way we could slide the rod and bearing together off once bolted/capped to get a good confirmation to matching surface.
Personally if the bearing surface does not simply have a good even fit it gets trashed. Hate to worry if it capped out well once it is assembled.

Like Capt said, some make a good unique bottle opener....

[Jay Smith]

Had a guy on this board "try" to sell me a set of "good" 280 rods that 2 out of the set would not crack cap up when I questioned the seller and his "good" usable set of rods he gave me a rash of sh"" , some don't not what's good and what's not !!

I build motors daily and rods are my most inspected part on motors I build , most of the time when one side does crack cap up and the other side doesn't the cap has been stressed or sprung , you will never get that rod to cap up correctly , chunk it and buy another they are a lot cheaper than cranks .. JMO

Jay

[Onetime]

Agree with Jay, if they don't line up properly the cap is jacked up, don't use it.

Usually saw this on very high RPM drag engines or offshore on and off the throttle rough water engines.

Wouldn't think you would see it on a 90 horsepower fishing motor but anything is possible.

[Jay Smith]

yep that is a bit strange ...

Jay

[pbxcomm]

Thanks to all for the replies and advice! Always helpful.
I'm going with Jay Smith and StratosVT.. It appears I have a bad rod and after much shopping I find the best price on a new OEM Rod is $232.00.
Is this the cost I'll expect to pay for a new rod? Are there other options out there?

Thanks again.

[Jay Smith]

Ouch , for a new one maybe , I'm not in the know about OMC parts , outboard parts can give one culture shock for sure ..

Jayb