As the title says I am wondering what plugs I need for the new engine.

This does sound like a stupid question, but I will give the reasons.

The new engine going in my 1990 is from a 1988 Toronado,
In the Haynes manual for 1988 only it calls for the R44LTS6(41-936 for platinum),
my 1990 calls for R45LTS6 ( 41-902 for the platinum)
and I am doing the ignition upgrade to the 97+ SC coils which call for 41-101( platinum only).
All these numbers ore for AC Delco plugs, since that is what I use

Right now I just installed the R45LTS6 ( what is supposed to be in the 90), but do plan on going back to platinum (41-902) as before the engine blew.


So should I be using what the engine calls for, what I used previously, or what the ignition calls for ( for the new coils).

It'* always the simple questions that are the toughest, LOL.

Mike,
W/o knowing the plugs by their numbers, are all the gaps the same or similar. Remembering that gap will also control heat to a certain degree. That may be the largest difference.

While being sold on how well Iridiums lasted in my 00 truck I have changed the 97SSEi out to TR-55'* and find good performance.

As long as you plan to run stock I'd stick w/a reasonable middle of the road. You need to consider the coils and igition system being slightly different.

And remember that a hotter spark can jump a gap better, so if you go with the TR55 on a stock NA motor, stick with the .060" stock gap.

I'm running 0.045"

(Magnavox Coil)

In your Bonneville? You are going to have problems. I run .055" on my TR55'* in the winter, and .050" on my TR6'* in the summer, and that'* on a car that needs it. You don't.

I am planning on keeping the correct gap, right now it is at 0.60". I just didn't know if I should use the plug recommended for the engine or the ignition system.

Iridium was another option I was looking at.

Skip the iridiums..they are just more expensive. Not really worth the cost in my book if you are going to do the proper maintenance on a car.

I can get them for the same price as the platinums, or pretty close anyhow.

Mmm I also chose to stay away from platinums..

Supercharged cars MUST stay away from platinums.

Mike, run the NGK V-Power TR55. You won't have any problems.