Spark Plugs

[dblankenbaker]

People might recommend other plugs, but people who have tried other plugs (myself included) and gone back to Champion swear by the stock Champions (part #412, I believe).

They should come gapped .035 out of the box (doesn't hurt to check).

I don't know anyone who has indexed their plugs. You need to buy little shims to do it properly. Indexing is **supposedly** good for 3-5% more horsepower, so once someone tries it and documents picking up 20hp with the exact same plugs... everyone will be doing it. Maybe I'll try it next Spring.

 

[Venom 1000TT]

I'm changing my spark plugs on my 96 GTS ( finally at 8,000 miles) . Any recommendations?
Was planning on staying with stock Champions. Book says gap between .033 & .038? Does anybody index their plugs?

 

[Tom Welch]

dblankenbaker is right on the money! USE STOCK PLUGS. $ 0.99 each at Pep Boys. Don't bother with the "gold" series, just the stock replacements.

Not everything costs an arm and a leg for the viper!

Tom
Http://btrviper.com

 

[Venom 1000TT]

Okay, I went out and bought 30 Champion stock plugs at $1.00 each. That way I have enough to get them indexed without using the washers. I'll gap them around .035. Thanks!

 

[Chuck 97 GTS]

Could someone please explain 'indexing the plugs' to the Zaino-wielding benchbuilders in the audience??

 

[dblankenbaker]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Could someone please explain 'indexing the plugs' to the Zaino-wielding benchbuilders in the audience??<HR></BLOCKQUOTE>

"Indexing" means aligning the plugs so the gap of each plug is pointing towards the combustion chamber. The theory is that you don't want the electrode blocking the path from the spark to the combustables. In the Viper, this means installing the plugs so the electrode is at the top (next to the top of the cylinder).

There are a couple of different schools of thought on indexing. One says the plug is okay as long as the electrode is in the top half of the arch. The second school is that the electrodes should be as close to optimal alignment (12 o'clock) as possible.

Since Jamie bought 30 plugs, this is what I would do:

1) Mark the insulator on each plug with a Sharpie to indicate where the gap is in the plug. The mark should be close to the cable end so you can see it with the plug installed.

2) Install the first plug until it is seated (finger tight... do not crush the washer!).

3) Check your mark for the location of the gap. If it's on top, tighten another 1/2 turn to crush the washer and point the gap downward. You're done with this cylinder. Go back to step 2.

4) If you cannot see the mark when a plug is seated (finger tight), keep trying plugs until you find one that fits with the gap up. You want "gap up" because when you add 1/2 turn to properly crush the washer, the gap will end up pointing down.

Note: Don't overtighten steel plugs into aluminum heads!!!

 

[GTS Bruce]

I think one of us might have their plugs indexed backward.On a magnum v8 the plug is indexed with the gap UP that is the open gap facing toward the center of the cylinder and the valves.If the gap is facing down the flame front propagates to the side of the combustion chamber not towrd the center of it.Is their something I missed or are we talking about the same thing. Bruce

 

[Venom 1000TT]

Thanks for the replies but I always face my plugs with the open gap facing up. Also the service manual recommends you torque the plugs at 20 ft/lbs.

 

[dblankenbaker]

If your heads are domed, or if your plugs are coming in more from the top down you'll want the gap up. That is actually much more common. I was speaking to Gen-1 heads which look like all the open space is below the plug.

Maybe Gen-2 heads are significantly different???

Perhaps there is someone out there with Gen-1 and Gen-2 heads on their bench who can make a recommendation.

db

PS - I have never tried indexing. In my mind, testing would require installing plugs electrode down, dynoing, and then installing plugs electrode up and dynoing.

 

[Venom 1000TT]

Let me say this: the Viper is Awesome Engineered!! I had those plugs out, indexed & back in the car in a little over an hour. Everything is a pleasure to work on ( I previosly owned 5 Vettes..what a nightmare to work on. Chevy should get a clue from Dodge engineering! ). I just removed the box on the passenger side( 4 screws ) and got access to all cylinders on that side and driver side was already accesable. While I was there I also checked the ohms on the coil packs ( also easy to get to by taking off 4 screws from cowl and 2 bolts from wipers ). Resitance was per service manuals specs. Plugs had 8,000 miles on them and were over due for changing. Why doesn't everyone service their own car!! It's such a pleasure knowing it's done and done right and no grease monkey griming up or scratching the car. Thank you Viper Engineering for making the car owner friendly!

 

[Venom 1000TT]

I went with gap UP 'cause I figured the injectors are above and the fuel will becoming down so I pointed the gap up.

 

[pauls]

Buy the index washers at Summit or Jegs, trade them around until you get it the right place. Anybody try opening the plug gap to 40 when using MSD wires?

 

[GTS Bruce]

Anyone try the Bosh 4 prong plugs? Bruce

 

[Todd Richmond]

According to this thread, the Bosch plugs would seem to be a bad idea due to 4x interference. However, the previous owner put them in my car - should I chuck them?

 

[TOOOFST]

With a higher quality wire and mods,I gap @ .38,agree with indexing theories.

 

[GTS Dean]

Most spark plugs are some distance off the centerline of the cylinder bore. I would place the gap facing the farthest cylinder wall. This way, the flame front will propagate unimpeded from the spark kernel after ignition.

 

[Mike H]

Is their an EXACT EXPERT to answer the ??? UP or Down with the gap?

 

[Jack B]

The Viper ignition will fire the plugs with gaps well beyond .040. It is quite possible to pick up a few extra hp by gapping them beyond the norm of .035-.038. The problem is that it is hard to change all the plugs (hot) between dyno runs. As far as the indexing - the gap should point towards the intake valve.

 

[jgfurr]

Okay, forgive me if this is a stupid question. Looking at the Moroso index washers from Jegs, there are kits with tapered and flat washers. Do I order both styles, or only one? How many kits should I order? What's the scoop?

 

[Marc Lublin]

Hey you guys with Dyno's and some time on your hands, why don't you see if indexing really gets us anything. My bet is very little, but I would be right on it if I was wrong. Check it out and post it!
Thanks

 

[Jack B]

Each kit has 30 washers. The viper will take the flat washer kit. The kit is comprised of (10) X three different spacer thicknesses. I will be doing a pull later this week. I'll install the indexing kit prior to the pull and compare it to my last pull. It will be the only diff.

The indexing procedure is quite common on the 2-cycle race vechicles such as jet ski's. It typically nets measurable hp gains. If you look at the viper combustion chamber design, with the plug seating and with the electrode's open end at approx 180 degrees it is turned away from the intake valve and further to the outside of the chamber. It appears that the open electrode end should be at approx zero degrees for optimum performance.

 

[Marc Lublin]

Any word on the before and after dyno numbers?