New spark plugs for my '95 300 I6
 

When I began to research installing new plugs into my engine, I thought that this was going to be a very simple thing. What could be more simple than putting in new plugs, right? Then I discovered that I could choose among carbon-core, platinum, & double platinum plugs. When I tried to find out if my engine required double platinum plugs, or if double platinum plugs would be okay or better for my engine, I could not find anyone (including my local Ford dealer!!) who could give me a definitive answer. I began to see rather vague information regarding whether or not this engine is a DIS (distributorless ignition system) engine, which is a consideration for spark plug type. My engine is fuel injected.

I'm coming to the conclusion that I'll just get some Autolite double platinum (plug #1525, if I remember correctly) plugs & install them. Does that plug sound correct?

I'm also looking in my engine bay, and I'm hoping that I can get at each plug to change them. Any potential problems on changing these plugs? Thanks for any tips.

Jim

It's always safe and rewarding to put the same manufacturer and number that it came with.

I prefer the stock Motorcraft plugs. Many on here have stated that the platinum plugs do not do well in the I6. If you go with what Ford put in you really can't go wrong. I have always run Motorcraft and when I pulled the engine after 366,000 miles the pistons rings and cylinders were in great shape. I was able to remove the pistons with out any problems as there was no ridge. These I6's are just one tough customer. Anyways the plugs Ford put in are the ones I'd run.

Motorcraft SP435 = copper

Motorcraft SP452 = Platinum

Some seem to like the copper, but recognize that it will wear more rapidly. It is said that it fires at a lower voltage.

The Platinum will work just fine and will last longer.

You cannot go wrong with either one. Check the gap... sometimes they get bumped in shipment and close the gap.

I'm happy to get either. What is the recommendation for a 300: 0.40 over, 0.45 off the head, DUI-HEI dizzy, big live wires, really big cam, short exhaust, Offy DP, mild p&p and Demon 625cfm??? Your right! Not alot of info...

:-huh Read 1986F150six's post again.

Motorcraft SP435 = copper

Motorcraft SP452 = Platinum

Thanks Harte3. Noted.

Any input on best plugs for a hotter ignition system such as the DUI-HEI thats almost ready to get stabbed into my BB6? They recommend wider gaps... got that. and copper may be less effective... but I have had engines run realy bad on one plug and great on another. That includes similar platinums and other exotic metal plugs.

BTW... If I wanted a frowny face, I would have gone to the Medicare side of the medical facility that I work at:-D. Forums are for discussions. Go rev your 4.9 and cheer up my Bro.

Stout36

Really nothing more to it than the ability to go with a wider gap with a stronger igniton. 45 is good for hei. Bigger gaps help leaner mixtures but are harder on coils.
Platinums should be no problem at all.

Most of this hot ignition stuff is just a lot of marketing hype.

Some of us use the plugs for EFI engines in carbed engines...a little bit longer reach. Gaps from 44 to 60 might be experimented with. Big ignitions and coils may be more a bragging rights thing than a performance thing. Only as much energy as it takes to fire the plug is going to be used with a lot left on the table with the big ignitions and coils...lots of marketing hype out there on those items.