I was wondering what kind of spark plugs everyone used with their MSD box? I have heard to get a colder plug and start gapping at .050? Is this pretty much what everyone else did? If so what plug is tough enough for the MSD 6A?

 

I have AC Delcos on my engine gapped to regular specs. Works good. Experiment and tell us if it is different for you.

 

You haven't burned the plugs up? The instructions says start at .050 I guess for more of a ball park area. I'll give it a shot and post my results. May be a day or two though.

 

Plugs are in good shape and still spark good.

 

OK, I gapped the plugs to .050 and hooked the msd box up and the car ran like crap. It felt like it was only running on half the cylinders. I used the wiring harness from msd too. I have the msd gm blaster coil. It has 4 connections on top and my wiring harness has only two connectors on it. I am wondering if this is the problem. I went back to the original ignition and the plugs are still gapped at .050 and the thing was missing bad and backfiring. Could the plugs be gapped too far with the msd hooked up (.050)? Any ideas?

 

I remember reading this post and being curious about different spark plug gaps. So I went and gapped mine to .050, .045, .040, and.035. Needless to say my results were similar to yours. I found the best gaps to be either .035 (stock) or .040. I only let it idle though, I did not drive it around or adjust the timing.

Yes the instructions say to start at .050-.060. I am sure that there are people who can drive better with the larger gap but we do not seem to be included in that facet.

 

Well, I gave up yesterday on trying to gap my plugs again. I thought having headers would make it easier to get to my plugs. Boy, was I mistaking. I had to cut a slit down the side of one of my spark plug sockets just to get two of them out. I think I will go to .040 today and see what happens. Thanks for the help.

 

All MSD ignition, bosch platinum .045" gapped plugs, no problems to date.
All stock ignition on my '91 camaro lo3, same plugs, no problems.
Ran the same gap/brand in my 'old 84 lg4, and '76 suburban (400) w/o problems as well.

 

Got a late start today and ended up gapping them to .040 and starting it up. Sounded better, the only thing is I didn't have time to give it a test drive. Guess I will be forced to test it on the way to work in the morning. Seems to run much better though.

Those bosch platinums are a regular plug right? What I mean is they only have one electrode not 4? I have seen the plugs with 4 electrodes and I don't see how they gap them.

 

Yes, they are the standard single electrode ones.
I've heard lots of pros and cons about platinums but, they've been very good to me.
I have tried the AC rapid fires for a day on my suburban during a full tune-up, worked great. Next morning, no start (didn't even sputter like it was trying). Found out they won't fire if they have any kind of oil on them.
Put the (quite) used platinums from my firebird in, never another starting problem.
That may just me being lucky with those plugs (only) though...

 

I am competly the opposite deadbird. I used platinums in the camaro and I had a horrible spark and a short life. I went back to AC Delco and am very happy with no problems right now.

Icoczirockz, I gapped mine back to .045 and it sounded OK. I played with the timing alittle and it sounded better. So, I will go drive it today and see how it fairs. I will see if there is a change in gas mileage or MAP Kpa.

Something I read though; filing down the ground electrode. How far down do people file it?

 

File it back just enough to unshroud the electrode tip.

 

Wow, that seems a bit radical. What does this do? Does this stretch your spark out or something or just give it a direct view of the piston?

 

Trying to gap your plugs per MSD specs is a great way for them to help you shorten ignition box life and make you purchase another box.
Just about everybody I know running MSD boxes is still running stock .035 gap in their plugs.

If your stock ignition was in good shape, you will not see and improvement in performance, mpg, etc...big misconception out there over this, but ask me how many times I've told guys just getting into the drag racing sport-footbrake class-this will be the case. And once they drop the cash and time into the set-up and run the same it sinks in. A good performing ignition system is going to do it's job regardless if it's a HEI, analog, or digital style.

Gapping the plugs to .040 would be max imo, anything bigger you need to personally take a feel of your box when the plugs are gapped at .050-.060 and feel how hot it gets trying to spark that gap. Anybody that's had a decent stereo system can vouge for the heat their sub amp would generate when driven hard for a long time at say a 2ohm load. The amp got real hot and this ignition box will get real hot too. Keep the gap .035 and just drive it, and dont be shocked when no improvements are noticed if your HEI was in correct working order.

I'm not talking down MSD or doggin anybody since I run the full system, just letting you know.

 

IHI,
I can agree with you on most of what you stated. I gapped my plugs from .035-.045 with out much noticible difference in mpg or MAP Kpa. I did notice it ran a little leaner. I have a Mega Squirt so yes, I can watch it and notice a difference in gas used. I also have my datalogs that illustrat this, most noticibly at idle where I went from 52-55 Kpa to 49-53 Kpa.

It also begs the question of why the factory would recomend a spark plug gap of .045 with the HEI and 4 cyl ignitions, then take them off the next model year and gap the plugs at .035. They obviosly had a reason. I do not question anyone's experience. I just say that everything and everyone's results will be different. If an MSD setup made no gains in anything at all, for anyone it would have been discovered long ago and MSD would have been out of buisness.

I will say that for racing, the older msd boxes don't do jack. The new ones......A world of difference in what they are capable of. Rev limiters, timing control, launch, multiple spark, longer spark. I know people who have run the same MSD set-up for years with only changing the spark plugs. How hot your coil and wires and plugs get is determined by the quality of your system. I said in an earlier post that MSD says to start at .050-.060 and go from there. To me that means "Experimentaion is neccesary for best results and component life."

Again, I agree with most of what you said. I found that the best gap would probably be .040. Which is below MSD's recomendation. I am not trying to question the validity of your experience or anyone elses, I just want to state MY experience also. This IS NOT meant as a flame to ANYONE that has previously responded.

 

I agree with both of you too. I wasn't expecting any power difference but I did want a better ignition. I too expected to have no notice at all if my original ignition is working. I was worried about the plug gap though. I guess for me .040 is going to work fine. Next, I want to experiment with different types of plugs and see what is best for my situation. I know in the past, without the MSD box, that champion plugs just didn't work well in my car. I did try some ngk's one time and they worked pretty good. I couldn't tell a difference at all with splitfires. Now, I need to experiment with plugs all over again. I have heard not to get the iridium plugs with MSD because they will not hold up to the spark.

I appreciate ya'lls information and will put it to use. I didn't tell ya'll what plugs I was using this time. I used AC Delco plug CR43TS. Probably the cheapest plug AC Delco puts out.

 

Do you know roughly what your compression is. The 43's are usually used in nitrous or high compression motors. For motors running 9-9.8:1 compression I'd recommend the 45's, 10:1-11:1 the 44's and high compression go with the 43's. The heat range wont affect hp output at all, it will just resist tendencies to predetonate.

Look at the strap on the plug after you've run it for awhile as this will indicate where you need to go with temp of the plug. There will be a noticible line across the strap that ideally you want in the elbow of the. If the strip is closer to the tip of the electrode your plug is too cold, if the line is closer to the base circle of the plug it's too hot. Get the line as close to the elbow and you'll be right on, very simple to look for and diagnoise.

I wanted to switch over the NGK's with this new motor but nobody in town carried the p/n I needed so I went with AFR's recommended AR3910. I've never run Autolites until this year, but so far they've worked great. With these racing plugs they already have the short electrode so you dont have to grind on it, but they are pricey, and I change mine every third race so I know all is in tip top condition since I have to for making money. Wish I could report longevity on these plugs for thousands of mmiles but I cant. With the Autolite the very last number is the heat range so mine are a 0 which is the coldest. Also know guys having good luck with Champions as well.

 

I have the msd digital six setup. My entire ignition system is msd. I follwed the instructions. The plugs should be gapped according to your compression. Also, msd told me absolutely no platinum plugs, splitfires, rapidfires etc etc. Use straight up regular AC delco plugs. If you want you can call msd and ask them. I'm sure they will tell you the info you need. YOu can also simply follow IHI's instructions. He knows what he's talking about.

IHI: Thanks for the heads up checking the strip thing. I didnt know that. I'll have to keep an eye on it for next time. Learn something new here every day.

 

I am now confused, and would like to know what you meant. You said to follow MSD instructions and gap according to your compression. It sounds like you followed the instructions per MSD and gapped them above .045. Yet you later said that a person should just follow what IHI said and gap them to .035 or .040 with a good system.

 

Yep,
You have two choices. Either follow IHI or call msd and ask them. I believe I gapped mine at .050. I will have to re-read the msd instructions to make sure. But they recommend gaps based on your compression ratio. It may make a difference as to what msd box you are using. I dont know. Sorry for the confusion. Should have just kept quiet...

 

Mine is 9.6:1. Thanks for the ring info too. That sounds like good info. I have always wondered about the cold and hot in spark plugs but nobody seemed to know either when I asked them.

 

LOL, you guys are killing me I tend to have a dragstrip train of thought 99% of the time and all my experiences are based from guys running all sorts of equipement and we all talk and share info. The greater percentage of guys running N/A motors (no matter what compression) use the standard .035-.045MAX plug gapping. For most of us weather daily driven or street/strip that gap is ideal. Just my .02 and that's all I'm gonna say bout that!!

 

I certainly can't dispute IHI becaue I know he knows what he's talking about.
I was only stating what I run which works well for me (which seems to be far and few between). I get nearly 30mpg on the highway with no hood and the windows down so I'm not going to question why.. I'll just enjoy untill it blows up I guess

 

DeadBird,
I tried that and was pleased with the increase of.7 mpg and the added manifold vaccum. I saw an idle Manifold Kpa of 47 with my hot cam from grinding the tip and the gap at .045. I will try it at .040 and .050 next and find the results. I even felt my coil and ignition box and they were cooler than almost everything in my engine, The firewall around it was hotter. Experimenting going well.

 

Man, I am gonna have to try that.

 

hmm interesting ,if u grind the tip wont it spark lees sence lees material is available

 

No. You are in effect unshrouding the tip of the elctrode to allow for better flame travel. Supposedly they will deteriorate faster though.

 

so how much lees will it last?20k miles?

 

I don't know. I have not put enough miles on my plugs for a noticible amount. I still have the same gap about 1,500 miles later though.

 

With my previous MSD-6A and current Mallory Hyfire VI, I have used AC Delco plugs with the standard .035 gap with no problems.

 

Of course you would, why wouldn't you? You could gap them to .055 for a little while and still be fine. .035 is for the weak factory ignition system.

 

The original poster asked if he needed to gap his plugs to .050. I just threw in what little info I had.

 

I sure appreciate all the info. I have gapped them to .040 and they seem to be holding up pretty good. It ran terrible at .050. Didn't feel like putting them up to .045. Pain to put the plugs in with the hedders.

 

I'm using the cheapest stock heat range Autolite Resistors from Wal mart, Taylor cut to size Wires (which I hate, the ****ing coil wire keeps burning out and causing misfires) and running an MSD 6 box (no rev limiter or any of that) The plugs are gapped to .40 I believe and I run a TON of nitrous to this motor (350 TPI) I have no clue if the MSD helped or not, but the motor doesn't miss or backfire even under around 250 horse worth of nitro.

 

When looking for a standard copper spark plug for use with nitrous or an upgraded ignition, is that referring to only the core or the electrode as well? With a plug such as the autolite racing spark plug, which has a cut back ground electrode that has a nickel plating, and a copper core, would that be ok to use?

 

just thought id bring this topic back up becasue it has good info, its in my favorites list.

would someone be able to explain cold plugs vs. hot plugs? is it meaning that cold plugs make combustion cooler? Im assuming its impossible to control the heat that the fuel burns, so im not sure of the need for different temperature plugs.


is it that the temp rating for the plug should match the temp that the engine runs at? higher compression running hotter right?


just hoping to stir up some answers or conversation agian.

 

Cool, I'm glad you brought this back up. Update: I have regapped mine back to original .035 and now the plugs are starting to wear out I think. I am starting to get a miss every once and a while. I checked them a while back and a couple of mine had obviously not been firing or something. The electrode was black and really appeared wet and generally nasty looking .

 

When it comes to plug temp getting the right heat range make the combination work properly. There is no real hp benefit to be had running a colder or hotter plug, but ultimately it does effect operation. Higher compression motors use colder plugs, lower compression motors use hotter plugs. Plug temp range determines how much fuel is burned and at what rate. Too cold of a plug for a motor will casue plug fouling and in-effecient fuel burn since not all of the fuel is being ignitied, to hot of a plug will lead to detonation since the plug end will remain hot and want to preignite the fuel before it actually recieves the spark from the distributor/proper timing event.

That's in a nutshell.

 

thats jus tthe nutshell i was hoping someone would explain, thanks. i also thought, octane rating for your gas also plays into this ill bet, higher needing a hotter plug possibly?

my stock 305 TPI, the parts store gave me AC Delco CR43TS, which you said may be too cold for my stock motor? i already ground my electrode so that the end is in line with the centerline of the plug. gapped to about .036-.037

thanks

 

Usually higher octane means the motor has higher compression to slow the burn down, and typically the plugs are cooler.

So long as your plugs are reading good and your not having drivablity problems, then you've got the right range for your motor.

 

So are you actually filing the side electrode or are you filing the tip that comes down off of that, the part across from the center electrode?

 

Best way to physically file the electrode down???

Hand file...bench grinder...