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-   -   Rod bolt torque after inspection (https://www.offshoreonly.com/forums/general-q/368544-rod-bolt-torque-after-inspection.html)

TomZ 09-26-2020 09:01 AM

Not that I know of, but I’ve only owned the boat three years.

zz28zz 09-26-2020 02:27 PM

Wow, that's ugly. Mine had a much cleaner break and the top ring was pretty much still there. Suspect yours ran that way for a while.

Not saying this is definitely the root cause but when you go back together, do some research on setting top-ring end-gap. I was astounded by all the correction factors that come into play. Piston type (forged,cast.hyper), how close top ring is to top of piston (think KB), hp/inch3 ratio, marine or non-marine, raw water cooling vs closed loop, NA vs forced induction, likelihood of detonation, likelihood of over-heat, fuel type, where it's measured in the bore. The list seems to go on forever and the factors change as technology evolves. You can start off at .016" and wind up over .090" after all the corrections are applied.

TomZ 09-26-2020 04:01 PM

Thanks for guidance. Yeah, that thing is pretty f’ugly, isn’t it? I have no idea of how long it ran like this.

When it goes back together, I’m going to follow JE’s instructions for setting piston to wall clearance and ring gap. So long as the bore isn’t bad, I’m sure honing can get me where I need to be for final clearance. I wish I was able to use a different set of rings, but if I stay with these pistons, I’m stuck.

I’ll probably go out and start taking some measurements this evening. I need to mark rods and caps.

Looking at that piston makes me feel ill. Lol

snapmorgan 09-27-2020 07:09 PM

I wouldn't waste my time installing rod bolts and resizing rods. You can buy a new set of floating wrist pin rods for $300 and be money and time ahead.

TomZ 09-27-2020 10:09 PM

I’m tending to agree.

TomZ 09-29-2020 05:17 PM

Block is at the machine shop to be cleaned and pressure tested. It will more likely than not need to be bored. The piston ring really took a chunk out of it. To me it looks like the ring hung and then broke. At first glance the piston looks like it suffered from detonation, but I think having lost half of the ring caused the piston to lose support which in turn scuffed it. I’m surprised the engine ran as good as it did.

The crank appears to be fine so it looks like either a 509 or 511 depending on how bad the bore ends up being. I really need to figure out the rod situation. I know the idea is to replace the factory rods with new ones. Any ideas? I was thinking I’d stick with I-beans with screws vs bolt/nut. Honestly, there is too much information posted here on OSO to be able to make a decision, lol.

snapmorgan 09-30-2020 08:07 AM

A set of the Eagle or Scat rods are all you would ever need for a stock 502. I personally would go ahead and get the 6.385" with floating pins since pistons have to be purchased anyway. Rotating assy should also be balanced


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