97 Riv - spark plugs and wires

[edwinn]

Originally Posted by rkvons

So you find time to do this type of stuff when you're not working at the particle accelerator?

That's pretty close .. more like aviation and space.


-Ed

[Tech II]

Since you like this stuff Ed, take a look a the picture of the electrodes on the 6 plugs, and what do you notice?

THIS IS A TEST!

[edwinn]

Originally Posted by Tech II

Since you like this stuff Ed, take a look a the picture of the electrodes on the 6 plugs, and what do you notice?

THIS IS A TEST!

The plugs look like they have a buildup of burned hydrocarbon deposits, or carbon deposits.. or becoming carbon fowled?

All are about the same shade of grey.. and that says to me that it was running somewhat lean and hot? or generally running good.
Certainly they're not wet and black!


-Ed

[Tech II]

I'll give you a hint:

Look at the electrodes......

[edwinn]

Originally Posted by Tech II

I'll give you a hint: Look at the electrodes......

The electrodes look like they're dissolved.. the explanation I found was: "high combustion chamber temperature can cause pre-ignition damage.. overheating is indicated by a white or gray center electrode insulator that also appears blistered.. with increase in electrode gap. Over advanced ignition timing, detonation and cooling system malfunctions also can cause spark plug overheating."

I ran 87 octane fuel for many years and it started to knock a lot.. so now using 89 grade Sunoco. The spark gaps were all (or mostly) too big on the original plugs.


-Ed

[Tech II]

You can separate the plugs into two groups of three, by looking at the shape of the center electrode and the "J" electrode.....

Since one coil fires both plugs at the same time(the one under compression gets the biggest spark, the other fires on the exhaust stroke), polarity out of the coil does not change(one coil terminal will be pos, the other terminal will be neg)......that means the spark jumps from the center electrode to the J bar on one plug, while on the companion plug it jumps from the J bar to the center electrode.......Thus on three of the plugs the center electrode will be more worn, and on the other three plugs, the J bar electrode will be more worn....

Typical life of the plugs was 100K, but more often than not, that did not happen.....

[edwinn]

Spark plugs reinstalled

Took the new plugs out to coat the threads with anti-seize on Saturday afternoon. NAPA had Permatex Copper stuff which i didn't take time to research. The NEW plugs were torqued at the recommended 132 in-lb, and man did they come out easy with a 1/4" drive speed handle.

Hope that copper stuff is ok.. and another re-work won't be necessary.


Spark plug threads coated with Permatex copper based anti-seize. Hope this stuff is ok!



Another example of coated spark plug threads.


Plug wire Fail

To make a long story short, I hadn't measured the LENGTH of the original wires and assumed the LONGEST wire went to Cylinder #6 (in back next to brake cylinder.) However the longest wire goes on Cyl #4 (center rear) but you don't find that out as a non-pro until getting to Cyl #6. So I had to remove #4 wire and put the 'long wire' on that plug!


Then, when trying to attach the wire on #6 plug (previously on #4), the connector inside the boot retracted ~1/2".. in effect shoving the cable out the back ~1/2 inch.


This plug wire has FAILED. It cannot be 'snapped' onto the spark plug. You can see a 'scuff mark' where the ring was before.


This NEW plug wire connector slipped 1/2" deeper into boot and can no longer snap onto the spark plug.

So now there are FIVE new wires, and ONE original wire on the engine!

The guy at Delcoline said he would replace the single wire, the whole set, or just give a refund. I'm trying to determine what to do now. There are FIVE new wires, and ONE old wire on the Riv temporarily.


Examine the wires on bench

There was time now to clean-up the old wires (like in summer 2012) and measure their length & resistance. Those numbers are presented in the next post.


Here are some photos of the OLD wires on the bench with a New wire thrown on top.


Here are the original 1996 plug wires compared to a New plug wire.




The original wires are sturdy and can be detached/attached several times without damage or failure.




The engine was running GREAT with the original wires. Why switch if they're ok?


Connectors are all still bright with no rust or corrosion.


This original (build in 1996) coil boot and connector look like new and is still rubbery!


Go ahead and laugh.. this is the kind of lab work i really like getting into.


What to do about the plug wires?

Now I'm wondering if the new Delco wires are a "one shot deal" meaning installed them ONCE and forget about ever taking them off? I didn't use gorilla tactics in attaching/detaching the wires either. They don't seem to be very sturdy or reliable.


What do you think about this issue?


-Ed

[edwinn]

Plug wire lab work

With the NEW set of wires already measured for length and resistance, and the ORIGINAL wires now available for testing, a comparison of Old/New can be done. The tables and charts below are the latest.. with a few unknowns which will be added once the original #6 cylinder wire is changed-out.

Hey, go ahead and laugh! Someone has to look at this stuff and post the results. Lol


Plug wire length

The following is self explanatory.






ORIGINAL WIRE RESISTANCE

The resistance of the original P.E.D. (Packard Electric Div) wires was measured and tabulated.


Ohms per foot can be found and plotted.




The original wire resistance plotted in ohms per foot, measured with a non auto-scaling DMM in two resistance ranges .

Very consistent!






NEW WIRE RESISTANCE

The resistance of the new ACDelco wires was measured and tabulated.


Ohms per foot can be found and plotted (updated from previous post.)




The new ACDelco wire resistance plotted in ohms per foot, measured with two different DMMs.





Conclusions

The OLD wires have a lower resistance with less variance. The NEW wires have 5.5x (approx five-times) higher resistance than the originals, typically 5,000 ohms/foot vs 900 ohms/foot. The original wires seem more sturdy, and can be detached and reattached without damaged or failure.


What do you think about all this?


-Ed

[maxwedge]

Way too much thread compound, just a dab at the most is required, most engineers do not recommend any.

[edwinn]

Originally Posted by maxwedge

Way too much thread compound, just a dab at the most is required, most engineers do not recommend any.

Yeah.. that day was rushed. I tried to get everything back together before frigid weather hit.. but didn't get even the NEW plug wires on!


Tried to call Permatex on Wed afternoon (day before X-giving) but no one answered the phone. That copper anti-seize seemed a little odd to me. It brought up visions of a mill file loaded with copper or aluminum.

That stuff was applied with a lab swab (cotton tip on wooden stick). The first two threads were avoided and only the lower half of the threads were coated. The instructions said to "apply thin coating to threads and flats of nuts." Tell you what.. will inspect for compound mushing-out around the plug chamfer/head area. Wouldn't want greasy dirt to collect there.


I'd say that if you're working on a racing engine, or taking the plugs out a lot, then no goop is needed. I'll be leaving the plugs in for the next 6-? 10 years? Please comment.


Riv plug wire length

Have pretty much completed the Riv plug wire data process. Only number missing is #6 original wire resistance.. because that wire is back on the engine.


..Note the longest wire goes on #4 center-rear cylinder.


Plug wire data table


This table contains all plug wire data.


Riv plug wire resistance

These charts display plug wires grouping front / back cylinders together. Chart on LEFT is total ohms for each wire, and chart on RIGHT is wire resistance per foot.

- -
Total resistance, and resistance per foot of wire. Resistive wires are to suppress ignition noise?


Wrap-up

At this time, the Riviera has five new Delco plug wires on it, and one original P.E.D. wire on #6 cylinder. I need to make a decision whether to exchange only the FAILED wire, or put the originals back on and take the whole set back due to reliability concerns.. and I'm serious about that!!


The ORIGINAL wires are 875 Ohms per foot +/- 4%, where as the NEW plug wires are 4,800 Ohms per foot +/- 25%.



Hey.. might as well make a federal project out of it.


-Ed

[enslow]

Before you slam ACDelco too much , which set did you get? The original equipment set is more expensive, so I'll assume the Professional series is lower quality. uploadfromtaptalk1385826660791.jpg

After a bit of searching, it looks like you have the 9746u (professional) which has an outer diameter of 7 mm. The original equipment is 746u which, from one website, has an outer diameter of 8 mm.

From your measurements, and this information, it kind of makes me want to change them out. I wonder how much fuel economy suffers?
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[edwinn]

Originally Posted by enslow

Before you slam ACDelco too much , which set did you get?

Thanks for the quick reply.

The ACDelco box is sitting on the counter. It's wire set 746U, GM# 19154586.


-Ed

[enslow]

Go and search the site below for your wires. The pictures you posted look more like the 9746u. Does the 746u look different now? Or did some one repackage a 9746u in a 746u box???

http://parts-catalog.acdelco.com/cat...log_search.php

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[maxwedge]

Cast iron head engine, I would use just a touch of this stuff or anti seize, very little needed if at all.

[edwinn]

Originally Posted by enslow

Go and search the site below for your wires. The pictures you posted look more like the 9746u. Does the 746u look different now? Or did some one repackage a 9746u in a 746u box??? http://parts-catalog.acdelco.com/cat...log_search.php

Thanks for the link. Here are two different wire images from there:

http://images.whisystems.com/smartpa...6U_PRIMARY.jpg

http://images.whisystems.com/smartpa...Alternate1.jpg

It's difficult to see any difference.

The wires I bought are 746U ACDELCO GM ORIGINAL EQUIPMENT according to the GM website above.




Will find out what the Delco guy says on Monday, and I'll bring the tray of original wires so he can see them.


The automotive guys around here are cool.. but they must think I'm nuts!



-Ed