On Thu, 22 Sep 2016 10:09:29 -0700 (PDT), Tim
wrote:

Surprisingly the do look pretty good for those hrs...

"These EFI engines are pretty easy on plugs. Some cars can go 100,000
miles on a set of plugs. That is 3000 hours or so.
This is 1500 hours on my 60 EFI (same motor Don has)
http://gfretwell.com/ftp/1500%20hour%20plug.jpg
It is the same basic block that Yamaha uses but you see they use a
longer plug and you see the difference on the threads. It ends up
deeper in the combustion chamber. I suppose things like that and a
little better intake manifold gets it the extra few horsepower that
lets them call the same engine a 70 instead of 60. It is supposed to
bench out around 67hp. The 60 was 63 or so.
It made virtually zero difference on my boat using the same prop when
I swapped."


Better change that "has" to had.
I was getting up to 75 hours on the Big Foot 60 so it was time to change to the MerCruiser 3.0.
Getting lots of use from it...30 hours so far with about a month left to add to that. ;-)