Rev engine to check plugs
 

Hi guys, I'm trying to get an answer on when to check plugs. I know his may sound odd, but I want to know how well or not my engines are running.
After running I feel I have to idle too long to get a good read.
can I rev engine up to 3000 for a few mins and then check? or is this not wise. Can someone please tell me how you do it properly in a boat.
cheers

Increasing revs with no load will not be an accurate way to assess burn. Ideally you do "plug cuts" where you run at wide open throttle, then cut the throttle back to idle very quickly and kill the ignition. That allows you to see what the burn is like at wide open throttle without the effects of a prolonged idle changing the way the plugs look.

I second this method!

Thanks guys, How long do I need to run for at the desired rpm to get a good read?

Maybe 60-90 seconds... should be adequate

Cheers

You can do the same method at your cruise RPM also. Be careful. Completely chopping the throttle on some boats may cause it to hook one way or the other.

I’d also start with a couple new plugs on the hotter cylinders like 7 & 8. As mentioned your cruising rpm is extremely important also as you spend most your time there. JMO

Make sure you really know how to read the plugs as well. Its not just looking at the color on the porcelain.

As far as im aware, im looking for a brown/ grey colour!!! Not Black - too Rich or whitish - too lean....
Saying that - i have my setup on the richer side to start with, so most likely be black
Thanks to all for your help - will do as discussed and see how i get on...