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Jerseydave
02-26-2012, 11:46 AM
Standard Autolite, NGK V-power, AC Delco Iridium???

Anyone have any thoughts/experience with the above?

Just wondering which ones will make my LT-1 run the best .

(I'd like to try the NGK V-power plugs)

mikeg205
02-26-2012, 12:17 PM
The iridiums - are they worth the price? - I run the MR43T - inexpensive, spec'd and I never have performance issues.

1redTA
02-26-2012, 12:28 PM
Ngk Tr-55.

Jerseydave
02-26-2012, 12:33 PM
Ngk Tr-55.

Skidim says the crossover from a MR43LTS is the NGK-TR5 (not tr55)
What's the difference if any? I figure you have lots of LT-1 experience from some of your other posts.....thanks.

1redTA
02-26-2012, 01:16 PM
yeah the 5 would be a little bit hotter of a plug probably a good thing. the higher the number for NGK the colder the plug for example the TR6 is great for nitrous hits around a 150hp the TR7 for forced induction with nitrous:-)

mikeg205
02-26-2012, 08:39 PM
plug temp....a debate that can be as delightful as an oil debate....but.... I would not go hotter in my precious 350.

... The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine. This is important because it determines the efficiency of plug self-cleaning and is determined by a number of factors, but primarily the actual temperature within the combustion chamber. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage. However, the level of torque currently being produced by the engine will strongly influence spark plug operating temperature because the maximum temperature and pressure occurs when the engine is operating near peak torque output (torque and RPM directly determine the power output). The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber but not vice versa. If the tip of the spark plug is too hot it can cause pre-ignition or sometimes detonation/knocking and damage may occur. If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark energy or the actual shorting-out of the spark current.


detotanation - knock - then either spark retard or piston damage...there's a current thread here that determined the engine detonation cause the damage... just sayin' ... I am no engine pro so I leave it to the experts...I'm conservative...

JimN
02-26-2012, 09:25 PM
The iridiums - are they worth the price? - I run the MR43T - inexpensive, spec'd and I never have performance issues.

You run that in an LT-1? The LT-1 takes MR43LTS and most pre-Vortec take MR-43LT.

mikeg205
02-26-2012, 09:54 PM
My manual stated MR43T.. I don't have a an LT-1... but even the Indmar manual called for the same plug. If you don't have the manual or can't get the right info...call Indmar I am sure they will help. In any case...I would run the recommended plug.

A new friend's motor failed the first time I went out with him with 1008 hours on this MCX. another here has an pristine s&s. I would run the exact plug the motor calls for.

Unless, you know 100% what you are doing or have the funds to play around I use the specified plug.

Ok ...I am ramblin...just sayin' spark plugs and oil makes a great debate.... you want more juice..supercharge...

If I am off base I expect the one ones with more knowledge to chime in. That's why I come here so much...love the discussion and even being questioned....

JimN
02-27-2012, 12:14 PM
My manual stated MR43T.. I don't have a an LT-1... but even the Indmar manual called for the same plug. If you don't have the manual or can't get the right info...call Indmar I am sure they will help. In any case...I would run the recommended plug.

A new friend's motor failed the first time I went out with him with 1008 hours on this MCX. another here has an pristine s&s. I would run the exact plug the motor calls for.

Unless, you know 100% what you are doing or have the funds to play around I use the specified plug.

Ok ...I am ramblin...just sayin' spark plugs and oil makes a great debate.... you want more juice..supercharge...

If I am off base I expect the one ones with more knowledge to chime in. That's why I come here so much...love the discussion and even being questioned....

I'm wondering why you mentioned your plugs in this thread when it's about LT-1 plugs- you didn't even state which engine you have.

Sorry about the LT vs T. I didn't have my manuals handy (and I do have the LT-1/TBI manuals, as well as LTR and some of the ones from new motors that came out in 2000/2001).

Your friends' boat- what parts did he change to non-OEM?

80starsmn
02-27-2012, 12:37 PM
For cripes sake the guy just wants to know what works best in the LT-1 motor, not a debate on how a plug works. My 96 PS 190 LT-1 manual says to use AC MR43LTS for the aluminum cylinder head, gap at 0.045". Works great lasts a long time!

Jerseydave
02-27-2012, 12:55 PM
I think I'm going with the stock AC MR43LTS. I've always liked AC plugs for GM engines and I doubt the NGK's would add much performance if any.

1redTA
02-27-2012, 01:22 PM
ac plugs are good the NGK never let me down on almost 400 horse power to the tires on the car in my sig pic

Stx221
02-27-2012, 01:32 PM
So here's a question for all of you. What's the difference between the MR43T, MR43LT, and the MR43LTS?

Table Rocker
02-27-2012, 03:36 PM
So here's a question for all of you. What's the difference between the MR43T, MR43LT, and the MR43LTS?
My understanding is the L stands for Long Nose and the S stands for Stainless Steel.

lt14me
05-06-2012, 07:03 PM
Just installed 8 champion RS12YC, the equivalent to the AC MR43LTS plugs. They came with the correct gap set at .035 they are just standard coper plugs.

Jerseydave
05-06-2012, 09:09 PM
Just installed 8 champion RS12YC, the equivalent to the AC MR43LTS plugs. They came with the correct gap set at .035 they are just standard coper plugs.

Plug gap for the LT-1 engine is .045 not .035

I've never been impressed with Champion plugs and GM uses AC plugs so that's what I went with.

lt14me
05-07-2012, 11:17 PM
I just went off my clymer gm inboard manual, and it stated .035 for the lt1.

lt14me
05-07-2012, 11:25 PM
Plug gap for the LT-1 engine is .045 not .035

I've never been impressed with Champion plugs and GM uses AC plugs so that's what I went with.

I do agree though that the champion plugs feel lighter, and I decided to return them for the ac delco's... 907 hours no need to chance it now.