Indexing sparkplugs

[NY Twin Turbo]

Does anyone bother to do this? Until recently I didn't want to bother. I also never thought there was any gains to be made. However, I had a little time one day and decided to try it. I believe I noticed a slight improvement with my idle. I also believe I could be going crazy and it could be nothing more than my imagination.

Iv'e got big injectors and maybe it helps to have the gap facing the intake valve? I don't know.

So, to make it easier, I decided to purchase indexing washers for my AR4132 plugs. Turns out, I don't like the washers because they are too loose on the plug's shank. They don't fit tight enough for the plugs to be center in the washer.

So I decided, as long as the ground strap doesn't have it's back to the intake valve, then this is good enough. No need to have it dead on. I don't have all day and 20 plugs to through away.

Any comments?

 

[SS/GN]

I was on the dyno with my friends Super stocker and he tested spark plugs all day I was so tired of changing plugs that day I could do it in my sleep. There was no benefit to indexing and opening the gaps up past .050 showed to gain. Now this was a N/A engine but I crewed on a Top Dragster for 5 years and he had a Jim Oddy 2365 HP blown motor and guess what, Jim said "indexing is for people with too much time". Hope this helps

 

[whitehot1]

I thought about indexing my plugs once but that was as far as it got,just being a thought.

I figure as long as i use the proper plugs and the engine idles great,part throttle is great and wide open throttle is great hell i'm good to go. I've tried many different brands and types of plugs and never seen any improvement over any of them in the way the engine ran. Now i just use the NGK - TR6 plugs in my Champion GN1 aluminum heads that are easy to locate at the parts stores and cheap too.

 

[NY Twin Turbo]

I was on the dyno with my friends Super stocker and he tested spark plugs all day I was so tired of changing plugs that day I could do it in my sleep. There was no benefit to indexing and opening the gaps up past .050 showed to gain. Now this was a N/A engine but I crewed on a Top Dragster for 5 years and he had a Jim Oddy 2365 HP blown motor and guess what, Jim said "indexing is for people with too much time". Hope this helps

Perfect! I like proven info. Next time I have time left over I'll just find something to polish. As for now......I have no time.

 

[chasmat2316]

I had a max effort BBC. That I had to index the plugs to keep from closing the gaps. On max effort n/a stuff I would say yes. Forced induction stuff- no need!!

 

[fastblackracing]

X2 on the no gains never could tell a difference. But I was not checking for idle quality--however I have noticed a slight improvement in idle by changing the cam sensor setting-----moving it slightly while the motor was running.

 

[NY Twin Turbo]

X2 on the no gains never could tell a difference. But I was not checking for idle quality--however I have noticed a slight improvement in idle by changing the cam sensor setting-----moving it slightly while the motor was running.

Well, like I said. It could be my imagination. I have 160lb injectors running on 93 pump-gas. Not E-85. So I figured the short pulse width might make the spray pattern at idle a little sloppy. And indexing the plugs might have helped. I also gave it a little more thought and said to myself........"Stop being a dumb-ass! Your over thinking it." But who knows?

That's why I posted the question. Who else has had any proven facts or experience?

 

[NY Twin Turbo]

X2 on the no gains never could tell a difference. But I was not checking for idle quality--however I have noticed a slight improvement in idle by changing the cam sensor setting-----moving it slightly while the motor was running.

Let's not forget....The car always runs better with new crystal clean plugs in it.

 

[fastblackracing]

Absolutely joey, you may very well be on to something for the idle quality. your combo is way different than most on here.

 

[delcowizzid]

its all about making the same power and getting a similar burn rate in all cylinders you will make more power if all the cylinders are making matching power levels.But if you have uneven length exhaust manifolds and hand ported heads that have never been port balanced on a flow bench and have no way to tune fuel or advance for every cylinder you wont release much in the way of power just by indexing but if you had the perfect even combo and you wanted all you could it might give a slight edge and well worth the effort

 

[RmvBfrFlght]

Indexing spark plugs came about due to high-dome pistons. The piston would hit the ground strap of the plug and close up the gap. To prevent this needed to locate the ground strap at the top of the chamber, problem fixed.

RemoveBeforeFlight

 

[NY Twin Turbo]

its all about making the same power and getting a similar burn rate in all cylinders you will make more power if all the cylinders are making matching power levels.But if you have uneven length exhaust manifolds and hand ported heads that have never been port balanced on a flow bench and have no way to tune fuel or advance for every cylinder you wont release much in the way of power just by indexing but if you had the perfect even combo and you wanted all you could it might give a slight edge and well worth the effort

My set-up is spot-on even and symmetrical. No home made port jobs done here. Champion all-out fully ported heads on an RPE built motor. I have 8 EGT probes in all primaries and one before each turbo. Equal length primaries on the headers. Internal directional baffles in the plenum to direct air flow to each intake runner. Individual cylinder tuning proves only a 7 percent differential in correction from the most leanest to richest cylinder.

The one thing I can't do is make individual cylinder correction fueling at idle. It's not allowed in XFI's tuning. So maybe the indexing of the plugs can take up what very little slack is left over to make it even?

Maybe? I don't know.......

 

[fastblackracing]

My set-up is spot-on even and symmetrical. No home made port jobs done here. Champion all-out fully ported heads on an RPE built motor. I have 8 EGT probes in all primaries and one before each turbo. Equal length primaries on the headers. Internal directional baffles in the plenum to direct air flow to each intake runner. Individual cylinder tuning proves only a 7 percent differential in correction from the most leanest to richest cylinder.

The one thing I can't do is make individual cylinder correction fueling at idle. It's not allowed in XFI's tuning. So maybe the indexing of the plugs can take up what very little slack is left over to make it even?

Maybe? I don't know.......

Joey what do you see for egt readings at full power and what would your A/F reading typically be?

 

[NY Twin Turbo]

Well, there isn't a lot of "typical" readings at full power. Because it's not often my car sees WOT.

At the track last year in September we made 3 passes. The same tune was used for the commute to the track. EGT's were in the high 1500's to 1600. Not much of a temperature variation between the hottest and coldest cylinder. About 32 degrees if I remember. AF's were at about 11.2 pump gas and alky and 20-21 psi of boost. We began to turn up the boost but traction from launch to mid track was hairy. It was clear no gains in ET were going to be made that day.

If more tuning was done, At higher boost levels, I would like to keep the EGT's at these same temperatures (just south of 16000 degrees). I would then add boost and richen the AF to keep EGT's at those temps.

Seems like the safest approach for a street tune.

 

[NY Twin Turbo]

Joey what do you see for egt readings at full power and what would your A/F reading typically be?

Also, I forgot to mention, My 6 EGT probes are all located exactly 1 inch from the head flanges and all are positioned at 90 degrees to gas flow direction. The XFI only reads EGT temps in 8 degree increments. For example, 1560 or 1568 or 1576. Never a 1570.

 

[T- Type Tim]

https://www.hotrodders.com/forum/indexing-plugs-79782-2.html?amp=1&utm_source=amp

 

[Coach]

Also, I forgot to mention, My 6 EGT probes are all located exactly 1 inch from the head flanges and all are positioned at 90 degrees to gas flow direction. The XFI only reads EGT temps in 8 degree increments. For example, 1560 or 1568 or 1576. Never a 1570.

Are your readings really in the 1500's??? With what fuel?

 

[NY Twin Turbo]

Are your readings really in the 1500's??? With what fuel?

Not typically on the street.

On the street........Usually, I lay the throttle down somewhat soft and bring boost up slowly. Then I'm only into the boost for about 3 seconds or so before I need to let off for safety reasons or to keep myself out of jail. I use Sunoco 93 pump gas and methanol injection. I typically keep the boost around 15 lbs. This will put my EGT's in the top half of 1300.

On the track.........Four years ago, we ran the same fuel/meth and street tune in its entirety. Completely unchanged from the ride down to Maryland. Just turned the boost up to 20. The only other main difference from a street blast was the time spent on the throttle. Instead of 3 second street blast, it was over 9 seconds. During this time the EGT's managed to climb into the mid 1500's.

We got 3 runs in that day. Drove it home and have not been there since with those EGT numbers or to the track.

Please feel free to comment. I would deeply appreciate any input you may have.

 

[T- Type Tim]

I’m going to index my plugs based on your comments about idle quality

 

[Coach]

Not typically on the street.

On the street........Usually, I lay the throttle down somewhat soft and bring boost up slowly. Then I'm only into the boost for about 3 seconds or so before I need to let off for safety reasons or to keep myself out of jail. I use Sunoco 93 pump gas and methanol injection. I typically keep the boost around 15 lbs. This will put my EGT's in the top half of 1300.

On the track.........Four years ago, we ran the same fuel/meth and street tune in its entirety. Completely unchanged from the ride down to Maryland. Just turned the boost up to 20. The only other main difference from a street blast was the time spent on the throttle. Instead of 3 second street blast, it was over 9 seconds. During this time the EGT's managed to climb into the mid 1500's.

We got 3 runs in that day. Drove it home and have not been there since with those EGT numbers or to the track.

Please feel free to comment. I would deeply appreciate any input you may have.

My EGT's have always seemed a little high but the car runs great and is extremely reliable. I see driving EGT's in the 1200's and sometimes higher. O2's are good and the car does make big power...approx 830fwhp on 93/Alky at 27#'s.
I was just curious if you threw out 1500 as a ref or if you really have seen that high.