AC DELCO Plug help!! # please
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
AC DELCO Plug help!! # please
Time for that tune up. Went to Auto zone, watched them search their computer and came home with AC Delco # 41-629 plugs. Anyone use these? the reason I ask is last time I ended up with some Autolite 26s.
The difference is astronomical in appearance!! The ACs have a compression ring-the tapered type-the Autolites don't-and the ACs are
about 1/2 inch longer on the thread/electrode length than the Autolites, WTH, I certainly don't want the wrong plug in there-any numbers on your ACs??? thanks in advance
The difference is astronomical in appearance!! The ACs have a compression ring-the tapered type-the Autolites don't-and the ACs are
about 1/2 inch longer on the thread/electrode length than the Autolites, WTH, I certainly don't want the wrong plug in there-any numbers on your ACs??? thanks in advance
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
Originally Posted by rick lambert
Time for that tune up. Went to Auto zone, watched them search their computer and came home with AC Delco # 41-629 plugs. Anyone use these? the reason I ask is last time I ended up with some Autolite 26s.
The difference is astronomical in appearance!! The ACs have a compression ring-the tapered type-the Autolites don't-and the ACs are
about 1/2 inch longer on the thread/electrode length than the Autolites, WTH, I certainly don't want the wrong plug in there-any numbers on your ACs??? thanks in advance
The difference is astronomical in appearance!! The ACs have a compression ring-the tapered type-the Autolites don't-and the ACs are
about 1/2 inch longer on the thread/electrode length than the Autolites, WTH, I certainly don't want the wrong plug in there-any numbers on your ACs??? thanks in advance
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
Originally Posted by rick lambert
Dang-I'm sorry! 
87 vette, 350 TPI, I deserved that 
87 vette, 350 TPI, I deserved that Autolite, not even in my Mustang and certainly not in my vette.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by aminnich
And your driving a what? Let's assume it is a corvette (Yugo's are in a diffferent forum). Ok, year? engine? stock? Vettes come with ac/delco fas as I know. Isn't autolite Ford?
ditch the Autolites and stick with OEM AC plugs. Your owners manual should tell you the exact type of AC plug to use....
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Owners manual-AC type FR3CLS, Haynes AC R43CTS, FSM-I can't find a recomendation or plug type! I know I like the ACs-Autozone, Nappa and Schucks all say AC 41-629----is this what you're using? 
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Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Right as usual Morley-thanks. Went to ACDelcos site and verified. Funny, thought guys here would jump all over it with plug numbers. :o
last time I needed plugs and new wires I didn't have time to do it,
and dreaded the knuckle busters-so I took it to a shop I trusted, and told them I wanted plugs and wires put in. She ran great and has always started without hesitation-great performance. So, this time I'm doing it and go oh sh#t, Autolites. Went and got the ACs and then noticed the difference-amazing-the ACs are approx. 3/4 from washer to
electrode-the Autolites are approx. 1/2 inch. Why they feel the need
to change numbers is mind boggling. You were right about the old number to-according to the owners manual. Funny I couldn't seem to find it in the FSM, maybe I didn't look hard enough. Thanks again
last time I needed plugs and new wires I didn't have time to do it,
and dreaded the knuckle busters-so I took it to a shop I trusted, and told them I wanted plugs and wires put in. She ran great and has always started without hesitation-great performance. So, this time I'm doing it and go oh sh#t, Autolites. Went and got the ACs and then noticed the difference-amazing-the ACs are approx. 3/4 from washer to
electrode-the Autolites are approx. 1/2 inch. Why they feel the need
to change numbers is mind boggling. You were right about the old number to-according to the owners manual. Funny I couldn't seem to find it in the FSM, maybe I didn't look hard enough. Thanks again
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
I just went through the plug madness myself. Trickflow says to use FR3LS plugs...so off to the parts store we go...I need 8 FR3LS plugs. first they want to know what car they are for. Doesn't matter, I need 8 FR3LS...For what car? The bimbo at the counter would not relent so I told her; 85 Camaro 305 F. Oh, you need R43TS. NO! I need 8 FR3LS. So she hands me off to one of the guys there. He looks them up, no listing but the number does cross ref to Autolites, NGK and Champion, but no cross to another AC plug number. So I had to find the new Delco number for myself and go back to play the "what car?" game all over again.
Thread Starter
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
So-did you end up getting the 41-629s? I never even thought about looking in the owners manual-have to say the general did a great job on that. If he would have made RR plugs a little easier it would have been nice. Funny thing is the #8 is always the easiest for me on the passenger side. I wonder exactly what the difference if any between the FR3CLS and the 41-629 other than number there is?
I never even thought about looking in the owners manual-have to say the general did a great job on that. If he would have made RR plugs a little easier it would have been nice. Funny thing is the #8 is always the easiest for me on the passenger side. I wonder exactly what the difference if any between the FR3CLS and the 41-629 other than number there is?
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
You gotta tell the parts guy what you need these days. When I first bought the 89 I went to get plugs and the counter guy insisted the plugs for the ZR1 will fit ("5.7, same thing" 
)Not even close!
)Not even close!
Melting Slicks
Joined: Apr 2004
Posts: 2,771
Likes: 138
From: cyberspace NY
ac delco r43cts is listed for my motor. They no longer exist...
Believe it or not, I did pull out autolite 26 that has 50,000 miles on them. Car runs great.
Yes I know this is 20 years old, but the motors are 30 years old.
Believe it or not, I did pull out autolite 26 that has 50,000 miles on them. Car runs great.
Yes I know this is 20 years old, but the motors are 30 years old.
Drifting
Joined: Jun 2020
Posts: 1,696
Likes: 728
From: Stay dangerous my friends
Melting Slicks
Joined: Nov 2016
Posts: 2,253
Likes: 3,076
From: So Cal
2023 C4 of the Year Finalist - Unmodified
You have the part number wrong.
R43TS is the standard duty taper seat plug used for many, many decades. It still exists on RockAuto for $1.66 each.
There is also a CR43TS. Same plug, but the leading "C" is a "commercial" application with a larger diameter center electrode. Everything else is the same as the R43TS. Rock Auto has CR43TS for the same $1.66 each. I've used both with no discernable difference, I change copper core plugs at about 35,000 mile intervals.
My 1988 aluminum head C4 used 3/4" reach gasketed plugs, IIRC, FR5LS. My 1992 LT1 has aluminum heads and it uses a taper seat plug. I put R44LTS in it. I think my 85 (iron heads) uses R45T.
R43TS is the standard duty taper seat plug used for many, many decades. It still exists on RockAuto for $1.66 each.
There is also a CR43TS. Same plug, but the leading "C" is a "commercial" application with a larger diameter center electrode. Everything else is the same as the R43TS. Rock Auto has CR43TS for the same $1.66 each. I've used both with no discernable difference, I change copper core plugs at about 35,000 mile intervals.
cast iron heads?