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Spark plug recommendation

KOPBET

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Hi all,

I want to replace the plugs in my engine, but since it no longer has the original heads I'm not sure what to use.

What spark plugs and gap would be appropriate for these '65/'66 "206" heads mated to my 454 BB? Are ACR 44s appropriate?

3856206....65-66...oval..CLOSED..396, 97cc chamber

Previous owner had installed Denso W20ES-U.
 

Yoda

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:w KOP,

I don't have a clue, but...Call THE source in Dallas ;) Mikey would know ;)

Bud
 

Vettehead Mikey

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Oooohhhhhhhhhh Nnnnnnoooooooooooooo!!!!!!!!!!

Not the dreaded spark plug question again. Can't we talk about synthetic oil or DOT5 brake fluid instead? :D

BTW, I never did get the SAE papers that supposedly 'prove' something.
 

KOPBET

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Oooohhhhhhhhhh Nnnnnnoooooooooooooo!!!!!!!!!!

Not the dreaded spark plug question again. Can't we talk about synthetic oil or DOT5 brake fluid instead? :D

BTW, I never did get the SAE papers that supposedly 'prove' something.

If I understand your (cynical) reply correctly, I think you're missing the point. I'm not looking for a generic "what spark plug should I use" answer. I'm looking for the correct plug to use in THAT particular 396 BB head.

:beer
 

KOPBET

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Never mind. I got eventually got my answer.

Thanks Bud.
 

pgtr

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Not the dreaded spark plug question again. Can't we talk about synthetic oil or DOT5 brake fluid instead? BTW, I never did get the SAE papers that supposedly 'prove' something.

You didn't? Well I never knew you were appointed judge and jury either. But me wonders what you 'proves' with posts like this? :D :D :D Keep waitin' I'm sure they're in the mail.
 

craig32

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I have no idea WTH you are talking about ....

:crazy
It's an ongoing difference of opinion. . . It sounded like you wanted to know what AC plugs to run, I would have suggested asking for plugs for the '66 396 at the parts counter, unless your 454 has electronic ignition, which probably uses a wider plug gap. For the record, what plugs were you recommended, for the 396 or the 454, or something completely different?

Craig
 

Vettehead Mikey

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It's an ongoing difference of opinion. . .

'Zactly. There's another old thread debating whether aftermarket plugs (of any type) allow an engine make more power, or not.

One group says yes, another says no.

The outstanding issue that the group that says yes has yet to show any proof. That's what the SAE papers are about.

As always it's a lot easier to show that something exists than doesn't exist.

I guess you can guess which camp I'm in, but I stand ready to be corrected and admit I'm stuck in the past.

There's a third group, well actually one individual, who brings nothing to the table except mudslinging on a personal level. I guess there's one in every group.:L
 

Yoda

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Before this gets completely out of control...

The original questions was
Hi all,

I want to replace the plugs in my engine, but since it no longer has the original heads I'm not sure what to use.

What spark plugs and gap would be appropriate for these '65/'66 "206" heads mated to my 454 BB? Are ACR 44s appropriate?

3856206....65-66...oval..CLOSED..396, 97cc chamber

Previous owner had installed Denso W20ES-U.

It had nothing what so ever to do with aftermarket "performance" plugs verse's stock plugs, it was a simple questions asked by a member with a question about spark plugs.

Before everyone goes hunting or word smithing to have a target, I suggest it is more important to HELP each other than to use "mudslinging" to make a point or defend a point!

It's Black and White here on the internet and even the funnest individual in person can be taken quite the opposite in typed text.

I hope KOPBET got the information he was looking for, and share's it as asked by Craig, and we move on ;)

Bud
 

bossvette

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Kopbet,
I would go with the plugs for the heads you have but more importantly I would check your static compression. I am not a "Big block" guy so I dont know for sure but I believe 97cc is a little small for a street engine of that (454) size. Hopefully someone that knows big blocks will come along. 44 in AC is usually a good start point for a street plug.
Craig sr.
 

Vettehead Mikey

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In rereading this string, I see one of my posts is not there. It was made from my work computer - which is known to have a mind of it's own. It should have been posted on the 28th to Kopbet.

In essence, I stated that the original plug for this head was an AC43. Most drivers have found this plug to be a little 'cold' for the street and conventional wisdom was to replace it with an AC44. These plugs are now getting difficult to find, (I think they're out of production) so many people are using an AC45, one step hotter.

The stock gap will work well, assuming you have a stock ignition system.

Here's cross reference chart that might show which plug to use:

http://www.globaldenso.com/PLUG/cross_reference/1001_01.html

Looks like your PO used the equivalent of an AC43. If these are working well for you, why change?

Sorry we got side tracked.
 

KOPBET

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For the record, what plugs were you recommended, for the 396 or the 454, or something completely different?

Craig

My main delema was (the PO) having gone from an open chamber 122cc head to a 97cc closed chamber head on a completely different engine and how that would affect plug selection and whether or not the head was the only compelling variable in this case. Parts counters here are computer screen readers only and could tell me what plug was used for the 396 CID if I knew the HP and year, with the heat range being the only discernable difference.

So, after some research and a lot of good input, it all seemed to come down to whether to use a R43XLS or a R44XLS. So as a starting point, I chose the latter. We'll see where we go from there.

I am not a "Big block" guy so I dont know for sure but I believe 97cc is a little small for a street engine of that (454) size.

Craig sr.

Not my baleywick, but by my calculations with all things being equal, going from 122cc to 97cc would change the CR from 8.5:1 to about 10.4:1. Whether or not you have a point remains in question. I don't know the answer either.

Looks like your PO used the equivalent of an AC43. If these are working well for you, why change?

The plugs were a Denso number that is not easily obtained around here for some reason. The cross reference was fine I guess, if I knew what factors were taken into account when he selected the Densos and if he knew whether the heads were not from a 454 Corvette engine. So, I set out on a mission to actually learn something about the whys and why-fors, knowing I had a missmatched block/head pair.

I guess it all came down to trust, and wanting to not repeat a mistake simply because someone else did. Plus, having only put a couple hundred miles on the car since purchasing it, it's hard to say if they were working for me, especially since the Densos looked like a little "cold" running plug.

Plus it never hurts to get alternative opinions when you're not an engine guru!

BTW - I guess it's a good thing you didn't see my thread on spark plug crush gaskets on another forum! :L

:w
 

gmjunkie

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I'm using AC R44's in my LS6 in my Olga truck!! R43's burn your eye's and it Loads Up!!:upthumbs
 

Hib Halverson

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Going from an open chamber to a closed chamber head on a street driven engine is not an issue as far as heat range goes.

That said, going from a 122cc chamber to a 97cc chamber on a BBC running on pump gas (even if it's 93-oct pump gas), is going to leave you with an engine that's quite detonation-prone. Thus, you want to do anything you can to remove any additional detonation enablers so you don't want to go any hotter with heat range then you are, now. The Denso W20ES-U is actually not a bad choice for street use. The Denso catalog shows that to be a 14mm, 13/16-hex, 3/4" reach, standard tip, u-groove plug. If I was buying new plugs, I'd stick with Denso, but go with the IW-20. It's in the "Iridium Power" line, so you get the benefit of the latest spark plug technology and it's a projected tip which is a little better for performance.
 

pgtr

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... AC44. These plugs are now getting difficult to find, (I think they're out of production) so many people are using an AC45, one step hotter.

Is this just a rumour or has this been confirmed that the AC R44TS is no longer being produced? They are as common as dirt around here and priced accordingly.
 

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