Spark Plugs for 4.0 SOHC

[Jim F]

Guggy
I only have 11,000 miles on my 98 so the plugs I am running are the OEM plugs. The research I did was on a 4 cylinder Chevy Cavalier with DIS ignition. The Ford DIS system is the same from the coils secondarys to the plugs. Once you go from the primary of the coils to the computer that is a different story among different manufacturers. Oh one other thing, there is one more coil on a V6 than on a 4 cylinder.

IgotTwo
Yes I also found that the DIS system is glanced over in Helms manuals and Chiltons manual. Most of the details I explained I found all over the web. Mostly on ACDelco's website and NGK's website. Anyone want to hear about indexing spark plugs?

 

[guggy]

Jim F

I know a bit about indexing plugs but can you give us the low down ?

Thanks

 

[Jim F]

From what I gathered the main reason to index a spark plug was to get the arm of the plug out of the way of the piston coming up on some race engines. Also by having the arms farthest away from the piston it would not block the spark when ignited and give a fraction most HP. Yes this sound trivial and the article I read used it as a reason most spark plugs do not need to be indexed.

 

[JDraper]

Jim's right on the indexing. What they do is align all the electrodes on the plugs so that they are pointing the same way inside the motor. This is done by adding shims (washers) under the head until it aligns properly. The other reason it is done is so that each cylinder has an (ideally) identical flame swirl pattern when it fires. This helps give consistent power cylinder-to-cylinder, which is important in high revving motors to help keep vibration down.

 

[ok89]

How hard is changing the plugs in the SOHC. I get the impression that the OHV is a PITA but is the SOHC just as bad?

 

[aldive]

a veritable nightmare in my opinion

 

[tbomb]

yeah, ive heard it was a nightmare on the sohc, so i didnt even try, i just had my mechanic do it for me

 

[97sport]

It's not too bad it took around 45 minutes to do mine.
If you jack up your front wheel and take it off, lift the plastic wheel well cover the plugs are right there. That is the only way i can get to the passenger side plugs.
The drivers side you can get from under the hood, but removing the tire makes it easy.

 

[IgotTwo]

I did find a good tool to help with spark plugs. We all know SOHC can be a horror. I'm not sure what you call it , I picked it up at a swap meet\car show and have never seen them anywhere else.
Let me try
You use it with 3/8 drive sets. A two inch metal disc about 1/2 inch thick with ratcheting mechanism (ON\OFF)just like socket. After you get the plug loose with a regular socket, subsititute this thing turning it by hand to spin the plug, a bolt etc. out the rest of the way.

Helps to avoid breaking plugs on the way in and out too.

Great for tight places, I'm sure some greater minds out there know what it is called. I try to take a picture of it.

Now that I have it, I've been using it all the time.