Ohm reading on spark plugs

[Frankenchevy]

I have a MSD 6efi CD box, Blaster SS coil and 8.5mm Super Conductor wires. MSD says to run one or two steps colder plugs and start at OEM plug gap (.060” in my case) and open up .005” incrementally until spark is dialed. I currently have NGK TR55 plugs and can get them to Ohm out just fine. I picked up a set of ACDelco MR43lts plugs which are one step colder than the R44lts that people typically run in Vortec headed applications when they are trying to avoid platinum or iridium plugs. I can’t get a single one to Ohm out properly out of the set of eight. The NGKs give me a reading in the mid 4Ks immediately. If I touch the ACDelcos just right, I can get them to start dropping below infinite (OL), but not consistently. There is a gentleman on a Jeep website who apparently has extensive dyno knowledge with various plug manufacturers and won’t touch ACDelcos. I know this is a can of worms only rivaled by the ‘which type of oil’ threads, but any suggestions? I was thinking of NGK TR6 plugs, but don’t want something that starts with a gap .010” off of my end goal so I don’t end up with a seriously angled electrode.

 

[bucket]

All of that went right over my head. I'm just here to learn...

 

[Frankenchevy]

The gentleman I was referring to is known as ‘JeepHammer’

Here’s the post:
https://www.google.com/amp/s/www.jeepforum.com/forum/f8/recommended-spark-plugs-msd-ignition-upgrade-1032454/?amp=1

He seems to swear by Nippon Denso or Autolite. I found Autolites in the correct reach, seat type and heat range, but they’re gapped at .050”. It’s an Autolite 104. Factory heat range/gap for vortecs from Autolite is the 605.

According to most manufacturers, you shouldn’t adjust gap much more than .008-.010” from where they leave the factory. So a plug that’s pre-gapped at .050” shouldn’t be opened up much further than .058-.060”.

I’m sure @Big Chip would know a thing or two about testing plugs, since aircraft guys tend to do it as part of their mech. safety checks for more obvious reasons.

 

[78C10BigTen]

All of that went right over my head. I'm just here to learn...

Im 100% with you on that!

 

[Camar068]

Sorry, can't help but I'll read up on it out of interest. I've always wanted to try the plasma plug setup. Can get expensive real quick though. ~$600 for a spark plug setup is expensive in my book.

 

[Frankenchevy]

Sorry, can't help but I'll read up on it out of interest. I've always wanted to try the plasma plug setup. Can get expensive real quick though. ~$600 for a spark plug setup is expensive in my book.

Can you elaborate on this. The plasma core plugs I’ve seen are about $16...

 

[QBuff02]

I have a MSD 6efi CD box, Blaster SS coil and 8.5mm Super Conductor wires. MSD says to run one or two steps colder plugs and start at OEM plug gap (.060” in my case) and open up .005” incrementally until spark is dialed. I currently have NGK TR55 plugs and can get them to Ohm out just fine. I picked up a set of ACDelco MR43lts plugs which are one step colder than the R44lts that people typically run in Vortec headed applications when they are trying to avoid platinum or iridium plugs. I can’t get a single one to Ohm out properly out of the set of eight. The NGKs give me a reading in the mid 4Ks immediately. If I touch the ACDelcos just right, I can get them to start dropping below infinite (OL), but not consistently. There is a gentleman on a Jeep website who apparently has extensive dyno knowledge with various plug manufacturers and won’t touch ACDelcos. I know this is a can of worms only rivaled by the ‘which type of oil’ threads, but any suggestions? I was thinking of NGK TR6 plugs, but don’t want something that starts with a gap .010” off of my end goal so I don’t end up with a seriously angled electrode.

Curious as to why the worry about spark plug ohm readings? I can only think of one other time I heard someone worried about it.. I'm running NGK V-Power plugs on my big block and my engine guy said that's the bulk of what he runs in any performance application. I'm running a complete MSD Ignition and I gapped the plugs based off of their recommendations for my ignition and compression ratio. I initially started at .040 just to see, and I noticed a start up and idle difference by working my way up to .060 which is where they are currently. I did have trouble with my ignition which turned out to be it had the wrong rotor bushing installed. Of course I only figured it out after it melted the distributor cap due to high heat from all the extra resistance of the carbon bushing being in place of the bronze one. Back to the plugs.. I asked about putting ACDelco's back in the engine when I was building it, and he said they're about the last spark plug he would use. So answering my own question it's obvious as to why you're checking it, but it's just something that no one ever really does. Unless you're running really high compression or something, I would certainly think right in the area of .060 would be more than sufficient for gap.

On a side note.. How do you like the Sniper system? I've been really considering it but have seen a lot of mixed reviews. Some complain and say it's junk and others ab-so-lutely rave about it. But just by reading reviews I feel like a lot of the problems are self inflicted or improper setup of the system.

 

[Frankenchevy]

Curious as to why the worry about spark plug ohm readings?

I nerd out on stuff. Good thing I did because all eight were junk, validating JeepHammer and your engine guys sentiment. Trust me this won’t be the other spark plug thread, lol!

You went .020 over your starting point. Did you do that all with one plug? It sounds like the TR55 would be perfect for you when the time comes to replace. The vortec head starts at .060 and several guys take them up to .080 for peak combustion/efficiency.

As for the sniper, I like it. The only problem is I’m always fiddling with settings, I can’t help my brain. I only sleep 4-5hours a day, so I need something to do, lol. I definitely agree that most problems are bad installs. Where it shines (obviously) is elevation change. I go from sea level in the bay to over 10,000 feet to recreate often enough that it was worth it. The timing control with the dual sync distributor is awesome too.

 

[dvdswan]

GTS

https://www.jegs.com/i/ACDelco/065/MR43LTS/10002/-1

Approximate Resistor Value
2.5-12k ohms

 

[Frankenchevy]

GTS

https://www.jegs.com/i/ACDelco/065/MR43LTS/10002/-1

Approximate Resistor Value
2.5-12k ohms

Those have too small of a starting gap for my application. Side note, I just tested a set of eight of those and all 8 failed.

 

[Big Chip]

I don't think the initial ohm reading is as critical as the reading after it's been in service. I think if you compare a plug out of the truck to a new one of the same brand and model they will be different. We use 5000 ohms as our cutoff but they are much lower, say 2500 ohms when new.

 

[QBuff02]

I nerd out on stuff. Good thing I did because all eight were junk, validating JeepHammer and your engine guys sentiment. Trust me this won’t be the other spark plug thread, lol!

You went .020 over your starting point. Did you do that all with one plug? It sounds like the TR55 would be perfect for you when the time comes to replace. The vortec head starts at .060 and several guys take them up to .080 for peak combustion/efficiency.

As for the sniper, I like it. The only problem is I’m always fiddling with settings, I can’t help my brain. I only sleep 4-5hours a day, so I need something to do, lol. I definitely agree that most problems are bad installs. Where it shines (obviously) is elevation change. I go from sea level in the bay to over 10,000 feet to recreate often enough that it was worth it. The timing control with the dual sync distributor is awesome too.

Sure did! Had I went like .030 over where they started from i'd have been kind of concerned. There was several thousandths difference between all 8 plugs when I started, and since they were brand new and I was "experimenting" I threw caution to the wind. Lol I've pulled them a couple of times to inspect them, especially after I rebuilt and reset the carb and everything is clean with good color so I'll keep running them until it's time to make a change.

What did you do for a fuel supply system for the Sniper?

 

[Frankenchevy]

What did you do for a fuel supply system for the Sniper?

It’s an 87 tank with an ep381 pump. All fuel lines are nicopp except where necessary I used
Earls Vapor Gaurd. I made sure everything was ethanol resistant.

 

[Camar068]

Can you elaborate on this. The plasma core plugs I’ve seen are about $16...

Sorry.....I should have said plasma ignition. Using plasma ignition "supposedly" burns all the gas creating more power and better MPG. Just a quick sample site from google... Been a while since I've read about it.

http://www.ionfireignition.com/

 

[Cuba]

I have a MSD 6efi CD box, Blaster SS coil and 8.5mm Super Conductor wires. MSD says to run one or two steps colder plugs and start at OEM plug gap (.060” in my case) and open up .005” incrementally until spark is dialed. I currently have NGK TR55 plugs and can get them to Ohm out just fine. I picked up a set of ACDelco MR43lts plugs which are one step colder than the R44lts that people typically run in Vortec headed applications when they are trying to avoid platinum or iridium plugs. I can’t get a single one to Ohm out properly out of the set of eight. The NGKs give me a reading in the mid 4Ks immediately. If I touch the ACDelcos just right, I can get them to start dropping below infinite (OL), but not consistently. There is a gentleman on a Jeep website who apparently has extensive dyno knowledge with various plug manufacturers and won’t touch ACDelcos. I know this is a can of worms only rivaled by the ‘which type of oil’ threads, but any suggestions? I was thinking of NGK TR6 plugs, but don’t want something that starts with a gap .010” off of my end goal so I don’t end up with a seriously angled electrode.

I no longer use resistance to verify electrical integrity. It's almost useless. The only time it's 100% accurate is when looking for a short.

Resistance will change on a plug with temperature change. Anything electrical that produces heat usually does, such as a light bulb.

That being said, what does MSD recommend on your setup? Which you've answered. Trial & error, IMO, is the only way to know for sure. Fuel also plays a part into how the plug wears, so there's always variables besides the ignition system.