Another Spark Plug Gap Thread.... LOL

[Vbb199]

Unless you are referring to the plugs on it as well, which arent under the cap,

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[Frankenchevy]

With 10.5:1 comp on tbi era heads, the internet will tell you delco r43 plugs which is colder than the normal r45 plug. I can only find 43 plugs in the marine variant, which is fine. I think they’re stainless instead.

A lot of guys with msd/hot coils swear by the ngk tr55 plugs. I believe they’re pre-gapped at .055. Which brings up another point, the internet says to never go more than .010 in either direction from the plug’s out of the box spec. So if it’s a .035 gap out of the box, don’t try to open it up to .055–you need to start with a different plug.

 

[Ricko1966]

Went and looked for the last 5 pin I bought.Hoping to find a number for you.Im sure the old gm number was 1941 but last one I bought I kinda got suckered. EBay thing, pretty sure it was listed as a 1941 but it arrived in a KEM box. That had been restickered as a Standard 330.

Edit.

Well while I was looking for this you and other people were already moving on, on this subject.Yea I wasn't thinking right you cannot use a 5 pin module with TBI

 

[Vbb199]

With 10.5:1 comp on tbi era heads, the internet will tell you delco r43 plugs which is colder than the normal r45 plug. I can only find 43 plugs in the marine variant, which is fine. I think they’re stainless instead.

A lot of guys with msd/hot coils swear by the ngk tr55 plugs. I believe they’re pre-gapped at .055. Which brings up another point, the internet says to never go more than .010 in either direction from the plug’s out of the box spec. So if it’s a .035 gap out of the box, don’t try to open it up to .055–you need to start with a different plug.

Im running vortec heads on my tbi, which is supposed to be aC delco R44LTS6 i think.
Those are set to something like .055-.06 gap.

Admittedly here, whatever ac delco plugs i stuck in there are for a .045 gap. I opened them to .060

Maybe i need to start with the aformentioned AC delco plugs ?

 

[Snoots]

Run the 44's on one bank and the 'whatever's' on the other bank. ~200 miles, pull 'em and read 'em.
Reading plugs don't lie.

 

[Vbb199]

Run the 44's on one bank and the 'whatever's' on the other bank. ~200 miles, pull 'em and read 'em.
Reading plugs don't lie.

Not a bad scheme.
After running the current plugs and checking them on the 60 gap, had decent heat cycles on all of them, maybe just a smidge rich. But thats likely because my CTS is irate with me and dumping fuel randomly because of bad readings (changing that today)

 

[Bextreme04]

Spark plugs come in heat ranges hotter and colder.The manufacturers all use their own numbering system some as the number goes up the heat goes down, and vice versa.Anyway 1 range colder as long as they do not foul is a cheap way to try to bring down preignition.As for module under the cap is it a 4 pin a 5 pin or a 7 pin. If it's 4 pin you can make a poormans knock sensor real cheap you replace the 4 pin with a 5 pin I think it was ac/delco 1941 module when 5th pin is grounded it pulls 4 degrees of timing out rig the 5th to ground how ever you want to momentary contact switch, toggle switch etc. Now you can bump timing if you only have ping at limited times and when your in those times ground the 5th pin.

Heat range on a spark plug is actually referring to how quickly or slowly a plug heats up. It's more of a heat dissipation rating. Effectively, a colder rating plug will dissipate heat quicker and not allow the plug to heat up as much, which can be better or worse depending on what you are trying to do. The functional side of this is correct though, if you are getting pre-ignition you can potentially fix it by going to a colder plug. Since you are running higher compression than stock and a more aggressive cam, you probably needed a 1 or 2 step colder plug anyways. I also had good results going from the 44TS to just a 44T. The S just means it has an extended tip. You might reduce your pre-ignition problem by just getting rid of the extended tip. You should be able to mess around with plugs pretty easy.. they arent expensive for those standard AC Delcos. R4xT will all fit... where "x" is the heat range. An S at the end means extended tip. An X at the end means wide gap so it will come with .060 gap in this application, a 6 at the end means the same thing. With AC Delco plugs, the lower the number, the colder the plug. It's on a range of 0-9.

Autozone now sells AC Delco parts. They sell R43TS6 for 2.99/ea and have them in store. That would be 1 range colder and a .060 gap. NAPA also has them for 2.69/ea. You can get R43T, R43TS, R43TS6 all for the same price at NAPA. I should also mention that when I look up the applicable spark plug for a 350 TBI Suburban, it comes back as an R43TS.... so you are already one heat range hotter than it calls for. You could even go to an R42TS and see what you get with that hot engine you are running @Vbb199 .

 

[Vbb199]

Heat range on a spark plug is actually referring to how quickly or slowly a plug heats up. It's more of a heat dissipation rating. Effectively, a colder rating plug will dissipate heat quicker and not allow the plug to heat up as much, which can be better or worse depending on what you are trying to do. The functional side of this is correct though, if you are getting pre-ignition you can potentially fix it by going to a colder plug. Since you are running higher compression than stock and a more aggressive cam, you probably needed a 1 or 2 step colder plug anyways. I also had good results going from the 44TS to just a 44T. The S just means it has an extended tip. You might reduce your pre-ignition problem by just getting rid of the extended tip. You should be able to mess around with plugs pretty easy.. they arent expensive for those standard AC Delcos. R4xT will all fit... where "x" is the heat range. An S at the end means extended tip. An X at the end means wide gap so it will come with .060 gap in this application, a 6 at the end means the same thing. With AC Delco plugs, the lower the number, the colder the plug. It's on a range of 0-9.

Autozone now sells AC Delco parts. They sell R43TS6 for 2.99/ea and have them in store. That would be 1 range colder and a .060 gap. NAPA also has them for 2.69/ea. You can get R43T, R43TS, R43TS6 all for the same price at NAPA. I should also mention that when I look up the applicable spark plug for a 350 TBI Suburban, it comes back as an R43TS.... so you are already one heat range hotter than it calls for. You could even go to an R42TS and see what you get with that hot engine you are running @Vbb199 .

I think upon returning from the offroad trip this weekend, im going to go and buy a set of R43TS6 and try them out... see how it does.

Watching a video i took, it reached 65mph in about 10 seconds from a stop, with a big, heavy, undergeared truck, and in that particular video, my transmissions line pressure wasnt comletely tuned.


My idea here with this truck is to have a naturally apirated truck that'll go fast as **** for 1989 fuel injection, and still be able to tow 6,000-7,000 pounds.


Im very closely reaching where i want to be, but this subject of plug gap is a fine tuned detail that i needed clarity on via input from other members on their setups, or just overall knowledge that i admittedly dont have total clarity on.


Im doing this on a working mans budget, while funding 2 other projects at the same time.

Baby steps.

 

[Vbb199]

Im a person of finer details, the small things that can be easily overlooked and discounted as unecessary. I want to fine tune this spark plug situation until im satisfied.


Again though, as i said, i believe my preignition is just simply because my total timing is on the brink of detonation, and best octane i can get is 93, and i was running uphill from a stop pulling collectively over 10,000 pounds with that engine.

Maybe im wrong, and i definitely agree now that i understand, maybe a lower heat range would help, but i was afterall reccommended by the chip tuner not to exceed the base 0° timing with his chip, i went against his advice and advanced it 2 more degrees.
Basing what ive read about the electronic advance, WOT advance, +2 from the prom, and +2 from me setting it manually, im at a borderline unsafe level.
1 misfire and it could be violent, which was my motive for running the coil, ign box, and regapping to a large gap, i wanted to utilize the maximum amount of thr combustion process and thus far it hasnt let me down. (Thankfully the KS did it job when i spark knocked pulling the trailer and kicked down timing)

Im really lacking in the flow of thr 500cfm tbi, which is why i machined the 46mm (650cfm) tbi.


I have a love for pushing **** to the limit, regardless of the consequences.
But i think i need to go back to 0° timing, and play this a little safer.

 

[Bextreme04]

I think upon returning from the offroad trip this weekend, im going to go and buy a set of R43TS6 and try them out... see how it does.

Watching a video i took, it reached 65mph in about 10 seconds from a stop, with a big, heavy, undergeared truck, and in that particular video, my transmissions line pressure wasnt comletely tuned.


My idea here with this truck is to have a naturally apirated truck that'll go fast as **** for 1989 fuel injection, and still be able to tow 6,000-7,000 pounds.


Im very closely reaching where i want to be, but this subject of plug gap is a fine tuned detail that i needed clarity on via input from other members on their setups, or just overall knowledge that i admittedly dont have total clarity on.


Im doing this on a working mans budget, while funding 2 other projects at the same time.

Baby steps.

I'm interested to see how it works out. It's really two completely different regimens and tunes for a fast unloaded tune and a loaded tow tune. I'm not sure how much it's going to like a long grade heavy pull with that high compression and timing set for a fast street truck.

 

[Vbb199]

I'm interested to see how it works out. It's really two completely different regimens and tunes for a fast unloaded tune and a loaded tow tune. I'm not sure how much it's going to like a long grade heavy pull with that high compression and timing set for a fast street truck.

Agreed, thats why i wanna go to a safer ignition timing and just keep a middle ground, regain my torque from a properly geared rear, 3.42 -> 4.10 and go with the higher flowing 46mm throttle body

 

[Bextreme04]

Agreed, thats why i wanna go to a safer ignition timing and just keep a middle ground, regain my torque from a properly geared rear, 3.42 -> 4.10 and go with the higher flowing 46mm throttle body

Or just go to an 0411 PCM with MPFI and then you'd be able to have a TOW/HAUL button that changes the ignition profile *cough, cough, LS swap*

 

[Vbb199]

Or just go to an 0411 PCM with MPFI and then you'd be able to have a TOW/HAUL button that changes the ignition profile *cough, cough, LS swap*

Get outta here with that ****!

 

[Bextreme04]

Get outta here with that ****!

 

[Vbb199]

Im gonna give LS a chance one day in something, idk what, but i cant bring myself to make a whole life out of it