Okay, so I changed from Bosch Platinum plugs to AC Delco plugs in my hopes to pass smog. I did pass (don't know if the plugs had much influence, since I did other things too)

Anyways... I was running the Bosch Platinum plugs and my car idled smoothly, and the RPMs stayed constant. These plugs were the Bosch Platinums with the super thin center electrode which is almost completely covered in the insulator, and a single ground electrode.

Now I am running AC Delco plugs. Just the standard ones. I gapped them all at .035 and put them in, and now my car runs rougher, almost feels like a misfire at times, but not as harsh (I've had 2 different episodes of misfires, and this isn't as dramatic). I have checked the wires, they are all in the right place and clicked on, none of them are burnt or anything.

I'm just wondering if anyone else has experienced anything like this? What could the issue be? Any Ideas?

 

Try a different set of delco's. I used the rapidfires and they were fine. Had to go back to regular ac plugs tho because of msd ignition system.

 

To distill a really complex subject into just a few lines:

For a spark to occur, there needs to be a path of ions for it to follow. For this path to develope means that some of the electrode material must *blow off*. This can be seen when you take a set of plugs out, after use, the center electrode, will be rounded off from material being blown off.

Now with you *long life* plugs they make the electrodes out of much harder materials so they won't erode as quickly.

The newer cars that have the 100,000 plugs also have better ignitions then the 3rd gens.

So when you take a plug designed for a new igntion system and try to use it on an earlier system, you can run into problems.

While AC plugs are what the engineers had when they designed they system, the Autolites do feature a *slightly* harder electrode, so you might get a little better life with those then the ACs.
Champions typically use the softest electrode material, and have the shortest life expectancy.

YMMV

 

personally i hate platinum plugs(due to the use of N2O) i have used many different plugs but the autoliite and the NGK seem to handle the performance usage quite well...

 

Autolite user here as well. I am not too big on the "platnium" phase going on. Good ol'e #25 or #26 will do it for me.

 

Captain,

I need your help - resistance is futile!

My 1990 GTA 305 TPI (I got in May) has 74K miles on it an has a bouncy tach and sputters / misfires under load. No problem, needs a tune up. Here is where I need your help:

I bought an MSD Coil, GM EXTERNAL HEI COIL, HIGH PERF. Part No. 8226. I bought regular AC Delco R45TS at KOI auto parts, but then found rapidfires at Autozone and bought those as well.

I don't know which ones to keep - you say you had to go back to regulars because of MSD - why?

I also bought an Accel cap and rotor - are these ok? I'm still trying to figure out which spark plug wires to use.

I'm in the middle of a search but this thread seemed so relevant I had to respond.

Thanks.

Number One.

 

taylor wires or msd wires work very well on our cars,plugs as mentioned before autolite 26-normally aspirated,25- up to 150 shot or supercharged!

 

I've tried all of the above ... like the rapid fires best!

 

Why did Captain Pickard say rapid fires don't work with MSD? I'm just using the MSD coil, not the entire ignition. Is he talking the MSD box (a.k.a. 6A(L))?

 

MSD 6AL will not work with platinum plugs, especially BOSCH, or even the rapid fires. The MSD will cause the combustion temps to get way to hot with platinum. Platinum plugs usually burn much hotter than regular plugs. When I first got my MSD 6AL I had the bosch plugs, by the time I pulled them out @ 200mi later, the electrodes were severly burnt, so hot it caused my car to run lean and the PCM added fuel to compensate so my mileage went down as well. Then I read a post here about the MSD box with platinum, and was told that they don't mix and I can confirm this, ( I also have the blaster coil ) ((I hear rapid fires are platinum as well)) So use a regular AC ( CHeap 43t) plug, or regular NGK ( UR4) for best results on an L98, I have vortec heads so I use a standard NGK TR55 ( non- platinum- non-iridium) which is a great plug I might add. No problems with the full MSD and NGK gapped @ .055 , MSD creates enough power to easily jump large gaps withhout strain on the system. This set up does seem to eat Ign. modules though.

 

DonP, no worries, everything on your list should work together just fine, including Rapidfires or any other plug(standard Delco, NGK, Accel, Autolite, Bosch, Splitfire, etc).

You also asked about wire sets... MSD makes good custom fit wire sets. Checkout Jegs and Summit. Each have large selections of wire sets from MSD, Taylor, and others.

You'll always find a few people who didn't have good luck with any product. But that hardly means everyone has had problems with those products. So use what you want to use.

Edit: Rapidfires are not platinum.

 

LAFireboyd,

Thanks. I guess what I'll end up with is a higher energy system due to the MSD coil. If I use good wires, and the rapidfires, would increasing the plug gap to .040 give a performace boost, or just pur a stain on the system.

For all I know, my problem with missing under load might be due to the stock plugs (for all I know) having 75K miles on them and the gaps have increased.

I think the first thing is pulling out the current set of plugs to see what is in there right now. The wires all look stock, however. At least they are in the stock routings, with the stock(?) wire looms around them.

 

So I've also noticed my gas mileage is way down, I got like 30 less miles than usual on the last 2 tanks... don't know if it's just the plugs...

I did the 02 sensor, and ran thicker oil all at the same time, so maybe it's a combination.

I think I'm gonna get some Rapid Fires, anyone know where I can get them for a Reasonable Price? (Less than 4.49 each)

I went back to my old o2 sensor just so I can either confirm or eliminate that possibility. Feels like it runs about the same new o2 or old.

 

DonP, with that ignition coil and good new wires you'll prolly be safe increasing your gap by .005 like you're thinking, BUT the specified gap for Rapidfires is .045, not .035 like other plugs. So an increase to .050 will prolly work fine. But don't blame me if it doesn't, lol.

It would be nice if your "miss" was as simple as your coil, plugs and wires, but it might not be. But if it's been 75,000 miles, it's time to change them anyway, and hopefully that'll solve the problem.

 

I'm hoping it's ignition too, but it could always be those damn injectors. We'll see.

$4.49 sound like what I paid each.

If the stock gap on these plugs is .045, I'll stick with that.

 

Some one mentioned that platinums don't work with the Msd because they run hotter, but didn't mention why they have a problem. The stock ignition fires the plug once each power stroke.
The Msd fires the plugs multiple times rapidly at each power stroke. Platinums work for the stock ignition, because the extra heat helps get a strong spark. If platinums are used with a Msd box with multiple firings they overheat and burn up.

 

Bruce, I love you man, but really, too simple . (An electrolitic effect through a medium of air?) Isn't it the molecules of the air that plasmate and the heat from this wears the edges . If it were actually the electrodes ionizing/plasmating you would have run out of material in very short order.

To quote off another site for anyone that cares to read some boring stuff:

"All that has to happen (to create a spark), is for the potential gradient across the gap, to be great enough to strip the electrons from the atoms surrounding the electrodes. This minimum spark starting voltage gradient is a few 10s of kV/inch at room temperature and pressure. When the potential gradient exceeds this value, the outermost electrons are stripped from the atoms of the air, causing the molecules to disintegrate; the result is a plasma, literally a soup of atomic nuclei and electrons that are disassociated from each other. The temperature of a plasma is very high; temperature, of course, is just the average kinetic energy per particle, and the particles in a plasma have LOTS of energy.

Unfortunately however, the temperature inside a spark is high enough, that a few atoms of the material usually do evaporate. If everything was sitting perfectly still, the material would transfer from the positive electrode to the negative one, eroding the positive (anode) and building up the negative (cathode). In a real-world dynamic environment like an engine, the vaporized metal atoms usually stay suspended and are lost. That's what rounds off the electrodes. The reason they both round off, is because an ignition spark is AC, i.e. several pulses of energy shuffling back and forth. So the electrodes take turns losing material. The one single advantage of platinum in this application is that its boiling point is VERY high, and therefore, very little of it boils off at the moment of truth.

The spark is all over with in a very short time after the electric impulse is gone; in less than a microsecond. The electrons and the atomic nuclei find each other rapidly and recombine, and it's all over with."

----------------

As for the platinum/MSD problem...

It's also the resistance in the circuit. Platinum is not the best conductor.

Also, platinum plugs run hotter when firing just one spark (thus their superior 'self' cleaning). When the MSD is firing a bunch under 3K y'think the temps may go up?

 

TheMysticWizard I've had my MSD-6A with coil and wires on my Z28 for about 100,000 mi. with no ill effects. I run Bosch platinum HR9BP plugs gapped at .055 and get typically 50,000 miles on them. So I've had pretty good luck with them. I've run the Bosch ever since the first plug change. IMO I don't understand what everyone's gripe is but, for non nitrous and NA they seem to be fine.
As far as motor oil stay with 5w30 preferably synthetic (Amsoil) and you can't go wrong.
My gas mileage has been in excess of 25 mpg on the open road and 20-21 average in town. Even when raising a little hell with it it is pretty good.

 

I really don't know what plugs to go with. I am thinking of going to the AcDelco Rapid Fires, since I don't like the AC Delco regulars... My car just doesn't feel right with them, idles all rough and stuff, although my pinging is pretty much gone, and I did turn the timing back to where it was before I lowered it for smog.

I also had the thought of going back to Bosch Platinums, cause my car ran good with those, other than the pinging.

As far as oil... I don't run synthetic, partially because I have 180k on this engine, and it already has some little leaks, I don't want it to leak worse (I dunno, I believe synthetic would make me leak or something) and partially because this thing has so many miles on it, the engine isn't worth the money of putting synthetic in it. In my new engine (hopefully will be built and in next summer) I will break in with dino oil, then switch to synthetic and never go back.

Right now I'm running 20w-50 because I was worried about my leaky valve seals failing me on the smog check. I also ran a bottle of Bardahl NO Smoke, the thick oil and the Bardahl cut down by about 2/3's on my smokey startup. I was thinking of switching to conventional 5w30 pretty soon here, see if that helps my mileage a lot... Question. Does Synthetic help mileage more than conventional oil?

I'm only getting about 15 mpg, and that was mostly freeway driving (20 miles to and from work, 95% freeway every day), something is wrong.

 

If you don't run a muti spark box, use any plug you like.

92BLKL98 it's not only us, MSD actually makes it a point to tell you not to run 'em.

 

I'm not really disagreeing with you just making a point that I've had pretty good success with that combination. Maybe they include this in their literature now but it did not seem to be an issue when I installed the MSD I did look for info on this at the time. I have been getting 50,000 mi on my plugs and they really were not that bad when I replaced them. The engine runs great with them. I know Jacobs Electronics made a point of that with their system when I installed it on my Blazer so I'm running AC in it.
As far as oil I've run synthetic since my car was new and no problems with leaking. IMO I would not use synthetic in a leaker due to the fact that synthetic molecular structure is uniform and not random such as dino oil and it may have a tendacy to perpetuate leaking plus it is a waste of a good oil. Fix the leak and you may be OK

 

What if you didn't have a leaky engine, but just a high milage oil consumer?

Reason I ask is that I have a Saturn with 148K, and it uses about a quart per 1000 miles. It's weird because it doesn't smoke out the back, no leaks, but some how that oil is disappearing. The car get's 5w30 and I check the oil often so I know it is consuming oil. Would this car not be a good choice for a synthetic? I'm thinking the synth would burn up even faster.

My GTA, on the other hand, has 75K miles and seems to hold its oil pretty well, considering the leaky valve seals. I'm thinking of switching this one to a synth.

 

I have ran Platinum +4's ever since I converted to TPI. Have had no problems at all. By the way "Saturn" should only be used here to describe the glow of oil rings shimmering in the glow of the garage lights. HaHa

 

bought a 91 z28 with 118000 miles 5 months ago, all stock, after a month , it stumbles and idles kind of rough. .. replaced spark plugs with Bosch plat +2 , installed MDS spark plug wires and new fuel filter . and a bottle of Slick 50 fuel clean additives. now the car runs great.

 

Kennerz,

Which NGK TR55's are you running? The TR55 (NGK-3951)or the TR55-1 (NGK-2683)?

-Eldon