Spark Plug Question

I

imspacemancraig

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Joined
May 24, 2009
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31301
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543
So my new mechanic was working on my Crusader engines last week and we replaced the spark plugs do to one engine not firing correctly. When he pulled them out, he saw that they were Champion plugs and made the comment that with a GM/Chevy block, I should only use AC Delco's or Autolites on them. Don't remember what he said about a Ford block, but that stuck in my head.

I did some searching and saw others make mention of that as well. Anyone know why? Also, which is better, the AC Delco or the Autolites?
 
I've always used the same AC Delco plug that came in my Mercruiser engine. I've never heard of a reason not to use Champion, I just stick with the manufacture recommendation which for mine was AC Delco.
 
I used NGK in my boat until three out of eight failed after 2 years. I went to the AC Delco marine plugs (stainless steel construction). Got them from Rock Auto for less that $2.00 a plug.
 
Hey Sandy, that link didn't work so well...

I was told that the AC Delco's and the Autolites have a longer inside that sticks out (forgot the right term) so that they burn hotter and therefore burn off the gas better. So essentially giving off a better spark.
 
e-t-b, can you tell me the AC stainless plug order number you got at Rock? My OEM AC plugs were MR43T.

Champion brought out a plug that was supposed to make SBC MerC engines run better because they protruded the tip as mentioned above. That Champ number was RV91MC (stock number 942m, not a stainless plug. Interesting that "AC" is the initials of 19th century inventor Albert Champion. The only plugs I've seen fail mechanically (break!) or electrically (not fire under compression) have been Bosch and Champion.
 
quote:
Originally posted by imspacemancraig he saw that they were Champion plugs and made the comment that with a GM/Chevy block, I should only use AC Delco's or Autolites on them.

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Your mechanic is a fool. As long as they are compatible and listed as equivalent, any brand of spark plug is interchangeable and can be used in any manufacturer's engine.

What would he use in a Dodge? A Toyota? A Honda? A Briggs and Stratton?
 
Assuming that the quality of all brands are similar, the brand of plug should not matter. What does matter is the size of the plug, extension of the plug insulator into the head, thread size, and heat range. All of these things should be covered easily by referencing a cross-reference chart, which should be available by the brand you buy. That being said, if you feel comfortable with one brand over another, go for it. I have heard of the plug separation problem with Champion plugs, but I have never seen it first hand. So for all I know it was made up by a competitor. I personally don't see the benefit of buying a $10 plug, so I happen to stick with the AC part number that came with my engine. But I'm sure others will argue with a specific brand because it gives them x amount of additional horsepower or 10% greater fuel economy. Me? I just don't believe in all of that hype. A plug is supposed to fire the fuel mixture. It either works or it doesn't work. The fuel mixture doesn't burn any differently if the electrode has two tips vs one tip. What is important is that you match the size and heat range.
 
For what its worth, I've used Champion plugs in my Crusader 350's and now my 454's for 17 years running now and have never had an issue. GVP, the previous Boatered God, told me personally that when they used MTBE? in gas, you needed a different plug than what was specified and he told me at the time the the Champion RV12YC was the recommended plug for both small and big block Crusaders. We still have non-ethanol gas here in Florida even though I believe MTBE is no longer used. Never had a spark issue to this day. Just my 2 cents.....but ya get what ya pay for.
 
MR43T is the right number - the M stands for marine. $1.46 each at Rock Auto with a $.50 each mail-in rebate. And they are branded at "alloy" not specifically stainless, but they sure look like stainless.
 
Thanks! I think I'll order a set regardless of the non-stainless. From what I saw on another forum, they used to be stainless and now are merely Plated. Champions are plated too, but the AC plating seems to hold up better. My OEM set of MR43T ran a very long time. Think it was 400 hours, maybe even 600... At first I thought the stainless version might be MR43LTS, but that seems to be a different application. Stainless, inherently, doesn't have the strength of ordinary steel. Maybe they had some bad luck.
 
quote:
Originally posted by cmariner32

........ GVP, the previous Boatered God, told me personally that when they used MTBE? in gas, you needed a different plug than what was specified ............
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Only if the engine manufacture recommended a different plug for fuel containing MTBE. Remember that boats, as well as cars, trucks, etc. travel from place to place and will be using fuel with different additives (or no additives). I would say this is another "old wive's tale".
 
quote:
Originally posted by j-d

............. Stainless, inherently, doesn't have the strength of ordinary steel. Maybe they had some bad luck.
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Stainless steel also does not conduct heat as well as plain steel. That's very important for spark plugs.

Buy what the manufacturer calls for or an equivalent replacement from another reliable manufacturer.
 
Stay away from Champion I have had three instances where the center section came loose and left the
acorn screwed in the block thank god nothing dropped in the cylinders
Stick with NGK or AC's
 
quote:
Originally posted by BUBBA

Stay away from Champion I have had three instances where the center section came loose and left the
acorn screwed in the block thank god nothing dropped in the cylinders
Stick with NGK or AC's

Click to expand...


Somewhere, on some web forum, there is someone posting the same thing about another brand of plug.

If they were really not as good as the other brands, they would be out of business by now.
 
I have a friend who races Sports Cars, he can get free Champion plugs and refuses them as he cosiders them junk. Besides racing he is also an engine builder.
 
quote:
Originally posted by BUBBA

Stay away from Champion I have had three instances where the center section came loose and left the
acorn screwed in the block thank god nothing dropped in the cylinders
Stick with NGK or AC's

Click to expand...


Same thing happened to me the last time, and I mean THE LAST TIME, I used Champion's. I have been changing plugs all my life, including Champions, and never had this happen. The risk of major engine damage is too great for me to ever use Champion's again.
 
quote:
Originally posted by Padraig

I have a friend who races Sports Cars, he can get free Champion plugs and refuses them as he cosiders them junk. Besides racing he is also an engine builder.

Click to expand...


I am pretty deep into racing myself, and you will not find a Champion plug anywhere near ANY of my engines. And yes, I too can get them on the arm as well.
 
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