Standard plug is AC Delco 41-983 platinum.

I would look at replacing plugs every other season or so unless a miss or problem shows sooner.

As for plug wires they should go I would think a minimum of 4 years or so depending on heat factor in engine bay, weather conditions and general wear and tear. If the engine is not missing most likely plug wires are fine.

If you need new plug wire sets we still have about a half a dozen sets in stock at our current price of $85 per set plus UPS shipping.

Best Regards,
Ray @ Raylar

Is there a requirement for Platinum, I thought those were used so cars could go 100K between tune ups. I was always told Champion or Autolite was the way to go, if your going to change them frequently anyways...

Just asking, thanks for the info-

A Plug for new Plugs
 

Use the factory recommended plug, its platinum but the marine engines loads , moisture and rotten fuel is hard on plugs. If you want you can just try cleaning them carefully with a toothbrush and some alcohol. Do not blast them! and do not use a wire brush or such! Re-gap them carefully to about .050" and if they are in good shape they should go until they start missing under loads. The new platinum plugs at a discount auto parts company should only run about $8-$11 dollars each so a new set won't break the bank. Remember to lightly coat the thread with a good lubricant and don't overtighten as this can break the plug (insulator) and the new plug is then toast!

Best Regards,
Ray @ Raylar

I am sure I am wrong, I thought the plugs for the 496 were Iridium plugs? I did a search on the part number ant got a Iridium plug not a Platinum. Also thought the gat was .35
Ray I know your the 496 guru. Just trying to make sure. Ill also be calling you soon for two sets of wires.

I'm afraid you are, AC Platinum 41-983 is what is written in the manual, as Ray said.
Otoh, I've yet to find an engine which doesn't like NGK plugs.
And NGK equivalents in this case are either PZTR5A-15 (platinum), or TR55IX (iridium).
What I can't understand is that NGK suggests that iridium is even better than platinum, but apparently the latter remains the more expensive...
Any views on that?