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Replacement Spark Plugs

anwat

anwat

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This is going to sound simple, but it's not. I just took the plugs out of my truck, they are Delco 41-821's . There aren't any more out there...I found one plug for sale on Amazon. No big deal, I'll find another manufacturer, right? Cross reference says there are only two, the Champion RV8C and the Autolite APP145. Those are just about as hard to find as the Delco's. But I did find the Champions, ordered them, and they look completely different. I understand the portion in the cylinder is what matters, but these seem to be a completely different plug. So, here's my question: Are these Champions OK to use? How about mixing them with the 4 Delco's that I have? I'm having trouble finding 8 of these at a reasonable price...cheapest I found the autolites is $70, which seems a little steep for plugs. Any suggestions on what to do next time when none of these are going to be available? I can't think there's not another similar spark plug out there that will fit in these heads. I think I have L19 heads, I know they're cast iron but haven't pulled the valve cover to get a number yet.


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What cross reference do you guys have access to that I don't? I can't even find a 41-821 listed in most of them, and the one that does have it only lists the Champion and Autolite as the same. Rock Auto is out, as is everyone else, since I don't think they make them anymore.
Wes Harden said:
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Are you telling me the R43TS will work? That would be simple to go to Oreilly and just pick them up...
 
70jimmy said:
NGK 3547

AC Delco AC10

Champion CHA 121

E3. EEE 340

All cross reference to that plug
Click to expand...
When I go to NGK's cross reference, it tells me a UR5GP is the cross reference to a Delco 41-821, but then it says maybe and I need to verify with the manufacturer. The UR5GP doesn't cross reference with the plug you put down, the 3547. See why I'm confused?
 
anwat said:
What cross reference do you guys have access to that I don't? I can't even find a 41-821 listed in most of them, and the one that does have it only lists the Champion and Autolite as the same. Rock Auto is out, as is everyone else, since I don't think they make them anymore.

Are you telling me the R43TS will work? That would be simple to go to Oreilly and just pick them up...
Click to expand...
41-821 is a platinum plug. I was assuming a gen 1 small plug sbc, which never had platinum. What is the engine you want plugs ?
 
70jimmy said:
I used napaonline.com to get the 4 I posted.
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OK, I see what you did...I can get those same four. might be worth a try, but I don't have a lot of faith in the website being correct if the actual cross reference from the manufacturer doesn't list any of those plugs. Good thing is I can at least go to the store and take a look at the plug and see if it's physically similar. Would help if I knew how Delco did their heat ranges, but I can't find that info either.
 
Wes Harden said:
41-821 is a platinum plug. I was assuming a gen 1 small plug sbc, which never had platinum. What is the engine you want plugs ?
Click to expand...
Therein lies the biggest issue. This is most likely a 93-94 454 with cast iron heads. I believe it to be a gen VI L21 block with older L19 heads. I know it doesn't have a roller cam, but it does have a six bolt timing cover, and a four bolt main, which doesn't make sense. I haven't taken off the valve covers to try to find a casting number on the heads yet to know for sure. So all I really have to go off of right now is the old plugs. There's a good chance the motor came from a Workhorse chassis truck from the 96-98 era, but I really don't know for sure.
 
Platinum is not necessary, any copper plug that fits and has the heat range you need is good enough
 
CR43ts some believe ethanol blend fuel (e85) can use a cooler plug. The C is copper.
 
NAPA says they will have the NGK UR5G plugs in a couple hours. If they look the same, they are going in, we can take a look after theres some miles on them and see about the heat range.
 
thats a platinum plug the NGK you are getting, I hope it works for you. What is the reason for the plug change at this time ? Platinum plugs should last 100k in good running engine.
 
My collector pipe came loose on the last outing. I didn't realize until I got home what the issue was. It was running way rich for quite some time, fouled the plugs and cat. Photos as soon as I get them out...I think they're beyond cleaning.
 
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