AC45 Spark Plug

[Timothy B.]

I have always been a purebred person and would like to have AC-45 non resistor plugs for my 67 300hp car but no way I'm paying 60+ for a set of eight.

The Autolite 295 looks like a normally priced plug, any thoughts on these or recommendations on another brand that gives good service. IMO, they all seem to be the same quality but I don't know much about spark plugs.

TIA for all comments.

[Michael H.]

Re: AC45 Spark Plug

In my 67 L79 I use the R45 and it works just fine with no issue's at all, save your money.

Mike

[Jim T.]

Re: AC45 Spark Plug

I have always liked the Champion spark plugs in my 1968 and 1970 Corvettes. The Champions in my 1968 have been used for a very long time now and the 68 327/350 still runs very good. The last time I changed Champions RJ12YC in the 1968 was 8/18/1986 the mileage was 78,766. Same Champions now with 97,798 miles.

[Bob W.]

Re: AC45 Spark Plug

Tim all plugs seam to work and last as long as the complete system is working right. IE wires cap rotor ect.

[Joe L.]

Re: AC45 Spark Plug

I have always been a purebred person and would like to have AC-45 non resistor plugs for my 67 300hp car but no way I'm paying 60+ for a set of eight.

The Autolite 295 looks like a normally priced plug, any thoughts on these or recommendations on another brand that gives good service. IMO, they all seem to be the same quality but I don't know much about spark plugs.

TIA for all comments.

Tim------


I agree with Jim. I've always found that Champion spark plugs run the best in Chevrolet V-8 engines. I've used them for years and I fully intend to keep using them.

[Frank D.]

Re: AC45 Spark Plug

I've tried a 1/2 dozen plugs in my '61 and '63 cars; AC, Champion, Denso, Autolite -- the NGK-XR4 is the only one that truly made a difference...
Its all I run now.

[Dan P.]

Re: AC45 Spark Plug

I have a set of NOS AC 45 plugs Dan 9one3 5one5 372one

[John D.]

Re: AC45 Spark Plug

[QUOTE=Timothy Barbieri (6542);758301]I have always been a purebred person and would like to have AC-45 non resistor plugs for my 67 300hp car but no way I'm paying 60+ for a set of eight.

The Autolite 295 looks like a normally priced plug, any thoughts on these or recommendations on another brand that gives good service. IMO, they all seem to be the same quality but I don't know much about spark plugs.

Tim, Buy a set of Commercial AC 45 spark plugs on Ebay. Same heat range. Same appearance but very heavy duty. You won't wear them out and they are reasonable as Corvette owners won't buy they.

They have a "C" on the plug. Then AC 45. John

[John D.]

Re: AC45 Spark Plug

I have had AC R45S (extended tip) plugs in my 67 L79 for a very long time.

[Duke W.]

Re: AC45 Spark Plug

I've tried a 1/2 dozen plugs in my '61 and '63 cars; AC, Champion, Denso, Autolite -- the NGK-XR4 is the only one that truly made a difference...
Its all I run now.

The XR-4 is not equivalent to the AC 45. First its a resistor plug, and I believe it has an extended tip, so it's the equivalent of the AC R45S.

Non-resistor plugs of equivalent heat range to the non-resistor AC 45 are available from NGK and Denso, the B4 and W-14U, respectively.

Denso spark plugs have been OE in Corvette engines since 1997.

Duke

[Domenic T.]

Re: AC45 Spark Plug

Back in 1970 a friend was racing a 327/365 in a small Britt car (I think a Austin).He was from San Diego and he Said He took the car to a Dino and tried 3 different sets of plugs. The Autolite gave the best HP, The Champ was equal for a while, and the AC was last. He said the Champion plugs ran good at the strip till the plating wore off.
I used Autolite after that, then the changed their # and the Auto Parts guys didn't know what # was the same as the old.

DOM

[Donald O.]

Re: AC45 Spark Plug

I have always liked the Champion spark plugs in my 1968 and 1970 Corvettes. The Champions in my 1968 have been used for a very long time now and the 68 327/350 still runs very good. The last time I changed Champions RJ12YC in the 1968 was 8/18/1986 the mileage was 78,766. Same Champions now with 97,798 miles.

I agree Jim.
I have them in my 67 327/350 and runs great. I replaced mine about 15-20 years ago (and about ~18k miles), because I thought that they should be due. They were fine from 1985 when I bought this Vette. I have been using Champions since the early 60s, and I have never had any kind of failure with them.

Don

[Richard M.]

Re: AC45 Spark Plug

I found these lying around here on a shelf. I forget where I got them or how long I've had them.

Are these like originals? I'm not sure the time build as there's no dates on the big box like other AC or Delco parts boxes. However there is a bar code on the box so it can't be that long ago.

PA300034.jpgPA300035.jpgPA300036.jpgPA300037.jpgPA300038.jpg

[Michael F.]

Re: AC45 Spark Plug

I have found that autolight works best for my 435 and LT-1, as for those that charge outrageous prices they are just greedy capitalist, but to each their own, who hurt the car hobby in general.

[Joe L.]

Re: AC45 Spark Plug

I found these lying around here on a shelf. I forget where I got them or how long I've had them.

Are these like originals? I'm not sure the time build as there's no dates on the big box like other AC or Delco parts boxes. However there is a bar code on the box so it ca't be that long ago.

[ATTACH=CONFIG]65438[/ATTACH][ATTACH=CONFIG]65439[/ATTACH][ATTACH=CONFIG]65440[/ATTACH][ATTACH=CONFIG]65441[/ATTACH][ATTACH=CONFIG]65442[/ATTACH]

Richard-------


The original AC 45 plugs had 4 THIN green rings. Later 45 plugs had the 3 thin rings + 1 thick ring as seen in the examples in your photos.

That's the primary feature that separates the Big $$$ NOS plugs from the more modest-priced NOS plugs. It's not a difference that means much to me, though.