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Indexing Spark Plugs on 5.0L?



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snocross1985

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Ah, shoulda known. :D

Spindle, you are a genius
 








cherrybomb

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aldive said:
Ideally you should also pick up some gas mileage. Let us know.

For you, and anyone else interested.

I've run about two tanks of gas through it since this tune-up with the indexed plugs.

While I don't have a very good highway miles test like you usually do Al, my daily commute is a constant. I drive a little over 3 miles each direction from my house to work and back, about 2/3 of which is on the freeway. I haven't deviated from that in the last two tanks.

On average, I'm still getting ~12mpg I could imply a .1 or .2 increase in mileage, but I'd say that's well within the margin for error.

So, on the mileage front, I'd say it's a wash.

As far as performance, the truck is definitely more responsive, and throttle response is better. I don't really think I picked up more power per say, but it's smoother, and more responsive.

All in all, not sure I'll index my plugs again, but it was a fun exercise.

Perhaps sometime later, I'll do a more scientific test, where I intentionally "index" the plugs toward the piston instead, and do a repeatable driving loop, then do the same again with plugs "indexed" toward the intake valve instead.

In theory, it seems like it would make a difference. But the old addage seems true here.

"In theory there is no difference between theory and practice, but in practice, there is."

Edit: I remembered finding someone else who did a much more scientific test than me. If you're interested in reading it you can find it here
 




old mechanic

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cherrybomb said:
For you, and anyone else interested.

I've run about two tanks of gas through it since this tune-up with the indexed plugs.

While I don't have a very good highway miles test like you usually do Al, my daily commute is a constant. I drive a little over 3 miles each direction from my house to work and back, about 2/3 of which is on the freeway. I haven't deviated from that in the last two tanks.

On average, I'm still getting ~12mpg I could imply a .1 or .2 increase in mileage, but I'd say that's well within the margin for error.

So, on the mileage front, I'd say it's a wash.

As far as performance, the truck is definitely more responsive, and throttle response is better. I don't really think I picked up more power per say, but it's smoother, and more responsive.

All in all, not sure I'll index my plugs again, but it was a fun exercise.

Perhaps sometime later, I'll do a more scientific test, where I intentionally "index" the plugs toward the piston instead, and do a repeatable driving loop, then do the same again with plugs "indexed" toward the intake valve instead.

In theory, it seems like it would make a difference. But the old addage seems true here.

"In theory there is no difference between theory and practice, but in practice, there is."

Edit: I remembered finding someone else who did a much more scientific test than me. If you're interested in reading it you can find it here
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I do not doubt you but you are the first person (that I know of) that ever said they could feel the difference after indexing the plugs. I usually try to index the plugs but I can hardly see some of the plugs on my EX nevermind index them. :D
 




cherrybomb

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Well, keep in mind I was also replacing quite possibly original wires and spark plugs. No doubt a large part of the improvment I felt had to do with that, rather than indexing the plugs.

Part of me wants to believe that my extra effort had some positive result though. :)
 




old mechanic

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cherrybomb said:
Well, keep in mind I was also replacing quite possibly original wires and spark plugs. No doubt a large part of the improvment I felt had to do with that, rather than indexing the plugs.

Part of me wants to believe that my extra effort had some positive result though. :)
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OPPS! I didn't see the "tune up AND indexing". Wether its indexing or some other little thing we do, in the long run it all adds up to a better performing vehicle. :)
 




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