Sparkplug confusion - L98/'87

[BamaVette87]

This is my first time to change out the plugs on my 1987 L97 engine (stock). Helms says that the plugs are supposed to be tapered. The owner's manual says to use FR3CLS. The newer Delco xref to the FR3CLS is a 41-629 (these are also what is currently in the car). Bought 8 of these. They are not tapered! The new plugs have a gasket on the seat. Should I be using a different plug?

(Some may have seen this post in another forum... Sorry for the "shotgun" approach, but I really need an answer! Don't want to put these plugs in if they are the wrong ones!)

 

[Edmond]

You should be okay using those newer Delco's. I just used Delco's about a month ago for my plugs and I haven't had any problems. They do have that little washer.

I can't remember if they were tapered or not.

Remember to use some anti-seize on the threads and do not torque the plugs too tight.

 

[BamaVette87]

Thanks, Edmond. Any ideas about torque values???

 

[Ken]

I can't remember if they were tapered or not.

I'm sure they were, Ed. (aluminum heads)

 

[BamaVette87]

I'm sure they were, Ed. (aluminum heads)

I'm confused again, Ken! Are you saying that the plug seats are supposed to be tapered because we have aluminum heads?

 

[Edmond]

Thanks, Edmond. Any ideas about torque values???

The torque values should be in that Helms manual. I could swear that it's in the 12-18 lb. range.

 

[G Winter]

I replaced the plugs on my 90 when I got it.It has the aluminum heads. Took the plugs with the 1 in of thread and a gasket. Someone had put the short taper seat plugs in , didn't look like they had been in to long which is a good thing considering the damage that could have been done to the heads. I looked at the seats in the plug holes and they looked tapered yet the plugs were not. To me the metal gaskets looked like they had a taper built into them. I can't say for sure though. The engine sure run a lot stronger with the right plugs in it, must have been trying to light the fire in the plug holes. :eyerole

 

[Ken]

The aluminum head engine came from the factory with tapered-seat plugs, but you can use gasketed style as well with no harm, the only possible effect is that it could result in inconsistent heat range.

And now, further insight into the spark plug arena ...

Most domestic engines use 14mm plug threads with reaches (lengths), as measured from the end of the threaded area to the seat, typically varying from 0.375-0.750 inch. Either a gasket or a tapered-seat configuration is used to seal the plug to the head. The wrenching hex is usually 5/8 or 13/16 inch.

A projected-nose plug "projects" the spark further into the chamber than a standard plug, and will nearly always offer improved performance if there is sufficient valve and piston clearance. However, many nitrous oxide users prefer to stay away from them because of excessive heat buildup in the tip that can cause detonation.

Projected plugs initiate the flame-front closer to the center of the combustion chamber, which has an effect similar to advancing the timing. This lets the total ignition advance be reduced, decreasing the chances of detonation while providing superior throttle response. A projected plug’s longer core nose provides a hotter plug at low speed to help prevent fouling.

As engine speed increases, the incoming air/fuel mixture flows across the core nose tip, providing charge cooling that effectively reduces the heat range for increased top-end detonation resistance.

 

[BamaVette87]

Thanks for the info, everyone! Now that I know there is not a mistake here, I will go ahead and install these new plugs (as soon as I figure out how to remove #2 and #8!).

 

[vette-dude]

Thanks for the info, everyone! Now that I know there is not a mistake here, I will go ahead and install these new plugs (as soon as I figure out how to remove #2 and #8!).

Remove the inner pass. wheel well and A-Arm cover. Just a few screws and it makes it so much easier!!!

Randy

 

[vetteboy86]

With a long extension on your ratchet you can reach it if you go through the wheel well. It usually takes me around 40 minutes to change my plugs, so dont feel bad it it takes that long.


Craig

 

[bill5674]

Like vettedude says take inerfender skirt off...much easier I was happy just to get a wrench in there much less a torque wrench.I just run them in by hand and snug them up with a wrench.

 

[BamaVette87]

Thanks everyone! Changed my plugs today. The #2 plug had the electrode almost touching the post (about .10 mm clearance). Maybe somebody had dropped it on the ground before installing it?? The #5 plug looked black. But this is the one where I had previously found the wire boot not pushed down all the way on the distributor cap. All the rest were picture-perfect (slightly brownish around the base and on top of the electrode).

Put the new ones in and they made a world of difference! (Coffee doesn't splash out of my cup at idle any more!!!!)

I really appreciate the tips on getting to #2 and #8. Taking the wheel-well panel off intimidated me, but I was able to go through the wheel-well opening to get #2 (never noticed that before!) and I used an open-end wrench on the back of the sparkplug socket to get #8.

Another job learned with help from forum members! Thanks all!

(Found this link to spark plug pictures...
http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html )

 

[I_R_DA_ONE]

Gentelmen

I have a late 86 and my handbook says that I should only use AC/ FR3LS plugs...I have found some at autoZone for 4.99 ea. AutoZone says that they are the RapidFire type plugs.... The replacement plugs are not of the rapid fire type....does this make a difference? My HP rating for this car is 235 HP with the late alum heads...the car is all original ....

what do you recommend??
thanks
Mike

 

[Edmond]

Mike,

You'll be fine with those plugs. Unless you're doing heavy modifying, Delco plugs will do you fine.

I just put those FR3LS plugs and they work fine.

It's also a good time to check the timing.

 

[I_R_DA_ONE]

thanks Edmund...
what do they mean by rapid fire ...is that just a sales gimik

thanks again
Mike

 

[Edmond]

thanks Edmund...
what do they mean by rapid fire ...is that just a sales gimik

thanks again
Mike

Mike,

Check this out: http://bellsouthpwp.net/p/a/padgett46/rapidf.htm

I guess you could call it a "high performance" plug. I personally think those type of plugs are more for modded engines.

 

[I_R_DA_ONE]

thanks Edmund

very good reading.....now I don't feel so ignorant about the plugs.... My car probably has those rapid fire plugs because it was used as a pace car in the northeast....
thanks again
Mike

 

[G Winter]

Mike you asked about the rapid fire plugs. Going to date myself here, but here goes . Back in the 60s the plugs all had a center electrode that was not smooth, it had what looked like a splined effect. In the 70s they did away with that and went to a smooth center electrode. I have no idea why other than maybe cost. Now they have the rapid fire plug, charge more for it and say it is special..... :eyerole :duh If I get out a plug made in the 60s... sure looks the same to me. Some say resistor is the diff. In 69 they had resistor plugs. Looks like a way to make more bucks on plugs to me. Don't get me wrong, not saying they might not be better. I kind of think they were and never could understand why they went away from them.

 

[I_R_DA_ONE]

Scav
Thanks for the insite.... I believe I will go with the AC/FR3LS plugs even tho they are twice the price of normal plugs....I am afraid of messing up my alum, heads...

thanks
Mike