Spark Plugs?

[Super D]

Question: How important is it to use the exact plugs as recommended in the service manual? What are the potential pro's and con's?
I recently swapped out my original plugs for a "regular" platinum plug with good results, but am now worried about them being too hot, etc. Do I need to worry?
Thanks,
Super D

[Tom Brown]

What engine and what plug?

[Super D]

Mercruiser 4.3 carb'd. Autolite plug, AP605.
Thanks for the reply!

[Stupid Fast]

YOu may get some run on if it is hot and you shut it down after a hard run....
4.3s seem to do that without the delcos in them....at least mine does..

[Lake Ape]

I assume you are using the correct size. I just bought a '67 302 chevy that some bozo put sparks plugs in that were to long! the tips broke off and destroyed the pistions! I will post pics if you all want.