AC Delco Spark Plug 46N alternatives

[thelawdoc]

Guys, I went in to an auto parts store today and asked for 6 Delco plugs, 46N. The guy says he is out of Delco plugs and gives me Denso plugs. The Denso box, containing 4 plugs, is marked: "W16EXR-U#4 / 3031#4 Resistor D9". I ask him how he knows that the Denso he is giving me can replace the Delco 46N and he says "the computer says so." Ok, I get home and I look online and I find a conversion chart for the 46N and on the chart it gives the following Denso choices:
Denso W16ES-U
Denso W16ESU
Denso stk 3025

So I am wondering. Firstly, am I correct that AC Delco 46N is the correct plug for my '66 250 I6 (carb&distrib)? Secondly, did he give me a proper alternative?

Thanks.
Alden

[old cool]

Hi Lawdoc. I pulled AC R44XLS out of my 66 PU with a 250. I wanted to bump up to get a little hotter plug thinking it would change performance in view of our ethenol gas. The parts guy felt I should only bump one level so I ended up with AC45XLS. It didn't really change performance. Anyway, I had no difficulty finding AC R45XLS or AC R46XLS. Not sure if they're are identical to our old school R44, 45, or 46.
So, I'm not sure where you shop Lawdoc, but AC plugs are in abundance.
Hope others respond. I don't think the AC's with XLS suffix are indentical. I too would like to know the best alternative.

[thelawdoc]

Old cool, thank you for responding. You know, the place I went to is a new place, Advance Auto Parts. They opened up a few months ago, apparently taking over from a well known auto parts chain that used to be there. I never heard of this company, and when the guy says he is out of AC Delco plugs, I wondered to myself what kind of auto parts store this could be. Maybe I'm an ignoramus, but when have you ever been to an auto parts store and they have no Delco plugs? This place was a good sized store, and I noticed that most of the stuff are brands that I never heard of in my 58 years. I never heard of Denso. He said they are the plugs in Toyotas. The plugs are marked as made in Japan. So I suppose they are good plugs -but they are not on the list of Denso alternatives to the Delco 46N that is listed online at SparkPlug CrossReference. Someone's computer is wrong here. I am not a mechanic, but I know enough to be careful about following manuals for machinery. My manual indicates that I have the choice of 46N for standard purposes, or 44N for cold. I admit that I do not know what 'cold' means for spark plugs, but the Denso plugs he gave me are also not shown to replace the 44N. Maybe the plugs he gave me will fire my cylinders -to me that is not sufficient. Many things in life appear fine to me while disaster is brewing below. If the manual says 46N/44N, then that -or a published equivalent, is what I want -unless guys here on the forum say otherwise. Excuse the ranting. I am irritated at myself for going in to a store to buy plugs and not taking with me a cross-reference list. You live and you learn. -Alden

[lha1992]

Originally Posted by thelawdoc

Old cool, thank you for responding. You know, the place I went to is a new place, Advance Auto Parts. They opened up a few months ago, apparently taking over from a well known auto parts chain that used to be there. I never heard of this company, and when the guy says he is out of AC Delco plugs, I wondered to myself what kind of auto parts store this could be. Maybe I'm an ignoramus, but when have you ever been to an auto parts store and they have no Delco plugs? This place was a good sized store, and I noticed that most of the stuff are brands that I never heard of in my 58 years. I never heard of Denso. He said they are the plugs in Toyotas. The plugs are marked as made in Japan. So I suppose they are good plugs -but they are not on the list of Denso alternatives to the Delco 46N that is listed online at SparkPlug CrossReference. Someone's computer is wrong here. I am not a mechanic, but I know enough to be careful about following manuals for machinery. My manual indicates that I have the choice of 46N for standard purposes, or 44N for cold. I admit that I do not know what 'cold' means for spark plugs, but the Denso plugs he gave me are also not shown to replace the 44N. Maybe the plugs he gave me will fire my cylinders -to me that is not sufficient. Many things in life appear fine to me while disaster is brewing below. If the manual says 46N/44N, then that -or a published equivalent, is what I want -unless guys here on the forum say otherwise. Excuse the ranting. I am irritated at myself for going in to a store to buy plugs and not taking with me a cross-reference list. You live and you learn. -Alden

The reference colder plug means the colder the spark will be for example a R43TS is a colder plug than a R44 or R45. The T at the if I remember right dealt with the size of the porcelain on the plugs. Theirs also a CR43TS which the C is a much thicker porcelain heavy duty plug compaired to a regular R43 version. Either way one thing for certain the lower the number the colder the spark an your combustion chamber wont burn as hot but the higher the number the hotter the burn.

Computer controlled cars now or for instance TBI engines usually like colder plugs but doesn't mean you can run a hotter plug but the computer will take over for advance an what not to make it run hotter. For our carbed engines we gotta do it manually an I preference R45 plugs usually.

Now for this instance Advanced Auto is a chain similar to Auto Zone an oreillys which you being in NYC y'all dont have alot of the big box chains. Sad to see because I use to work at Oreillys an during training they would talk about the Northeast being the only area that still had mom an pop parts places.

But at my time working at Oreillys I ALWAYS was reminding my coworkers about if a customer comes in with a GM car sell them a delco plug. Common sense right? Nope not to alot of people an I would always state my experience of working on cars how running other plugs screws stuff up.

In all honesty take the denso plugs back. Ive heard some horror stories how some plugs may fit right but end up burning a valve or something bad. Whoever sold you that plug shoulda ordered you a delco or cross-referenced it for you to be sure. Even in my small 21yrs compared to yours ive never heard of a so called parts place to not have a delco plug. Thats ridiculous!

[thelawdoc]

Iha1992, thank you very much for your response. I did a bit of reading on regular and cold spark plugs today and you have helped me get a grasp of it. I also happy to hear that Advance is a reputable place. The big chain auto parts stores are in Brooklyn, but the closest major chain store, while not far in miles, is very far with traffic. It is an excursion. I walk a lot these days because it is nearly impossible to find a space to park my truck in this city once I leave my driveway. Anyway, while Advance may be a big name chain, their people at the store near me do not seem very knowledgeable about cars. Not because they are young. Rather, they have little connection to, or experience with cars, mechanical, etc. They are like minimum wage college students and grads who could not find work in their chosen field. In the fifties and sixties, the average 17 year old could overhaul an engine. I will return the plugs. That is for sure. I refuse to believe that I would have come out of Autozone or Pepboys, or O'Reilly's, Sears, and most any other chain, with the Denso plugs. I would not mind being corrected. -Alden

[thelawdoc]

UPDATE: So I went back to Advance Auto with a printout of the Delco equivalents. They were perfectly amenable to taking the Denso plugs back even though I had put the plugs in my truck. They ordered for me Autolite 405 plugs which will come in this week. And they are giving me a $20 gift card. Apparently, we have an auto parts store here that I can deal with. I have no problem with someone making a mistake and then correcting it. Still, prudence dictates that when going to buy a part, go with your own information. Do not rely on the information in store computers. I love the computer age, but we still have some time to go yet before we can follow a computer's advice blindly. -Alden