I know everyone has an opinion on this and that's fine with me. What spark plugs do well for 3400 motors? Just started our son's car to move it to the garage to get things ready to flush the coolant system and it's rough when it first starts. Pulled one of the plugs just to look at it and it's not in the best of shape. Over a 1/16th gap and the cathode is all but gone. I'm looking at Bosch and AC Delco. I've used those E3's on another car of mine and those did good. There are just toooooo many choices

 

ac delco!

 

Ok...that's what I ended up going with. Thanks for the response. Now to see if this helps

 

I know this is a little late... AC Delcos or I've used NGK Platinum plugs. Which some AC plugs are re-branded NGK's.

You may want to check this thread for other tips with maintenance for that car. Those 3400's are nice and reliable (like anything, they aren't perfect, but I have no complaints with the ones I've had).
https://montecarloforum.com/forum/fw...0-miles-46078/

 

Thank you for the link. I've already planned on a coolant flush. It's brown and just nasty looking. Drove it home from Illinois and it never got over 165deg ( guess ) looks like it was mixed with green.

Appreciate the help guys

 

There is a lot of discussions on the net around spark plugs.

My take is stay away from Bosch (read it as hell what do I know)

I would go with O.E.M. or better.

ac delco/ngk/denso are my preferences.

I go platinum at minimum I put a set of denso iridiums in my 06 monty just last weekend. I do this mainly for change out frequency as in I want them to go at least 60k

 

I used either AC Delco or NGK whichever is available or has a good deal.

 

I went with AC Delco. I heard Bosch aren't very good for our cars, and this was from reviews all over the web.