NGK Plugs

**YENKO DEUCE REGISTRY** · #1 06-01-2007, 05:06 PM

Anyone know the NGK equivalent for AC-Delco R43's or R44's?

DarrenX33 · #2 06-01-2007, 05:28 PM

Marlin-

I went with the XR5 which was what we determined here to be the R43 equivalent. However, I believe you need them tapered for the Deuce.. End of summer last year I went with a hotter plug which is the XR4.

**Mr70** · #3 06-01-2007, 05:46 PM

My 291 heads use AC-Delco R43T originally.
Last year Rob C. helped me determine the NGK equivalent for those was UR5,stock #2771.
These are magnificent spark plugs and REALLY wake up the combustion chamber for me.

**YENKO DEUCE REGISTRY** · #4 06-01-2007, 06:00 PM

Hmmmm... so what's an NGK 'R5671A-8'?? A buddy thinks they will fit the Deuce

Darren, did you notice an improvement with the NGK's vs. the AC's??

3macs1 · #5 06-01-2007, 07:25 PM

[ QUOTE ]
Hmmmm... so what's an NGK 'R5671A-8'?? A buddy thinks they will fit the Deuce

Pretty sure that is one of their racing series plugs equivalent to a AC 41XL.Not sure what you are running in the car now to see what it would cross to.We run NGK in just about everything right down to the snowblowers and there is no comparision to running a AC at least in a BBC on the street. We were replacing AC every other day from fouling or just going dead. We don't see that in the BBC with the NGK.
Have to say that is a interesting plug Rick is running and I will have to do some checking since we call for the R43T also in one engine but run a 4323.Hope I got the right ones in.

**SmallHurst** · #6 06-01-2007, 07:55 PM

Marlin,

I can post to you what I have sitting in my tool box at home. They were recommended to me and I changed out 2 years ago at the track. I need to stick a fresh set in so that I won't have Pete pestering me about changing my plugs. I believe that I had AC 43's in mine. Stock plug for mine was AC 45's. Spark plugs.com is a good place to get your plugs. I checked with your car and they were showing XR4's (part # 5858). I believe that mine are NGK racing plugs.

@wot · #7 06-01-2007, 08:59 PM

Using a Br6FS in my L78 as a replacement.

DarrenX33 · #8 06-01-2007, 10:12 PM

[ QUOTE ]
Darren, did you notice an improvement with the NGK's vs. the AC's??

[/ QUOTE ]

Yeah, like Rick says they seem to add more punch. I really noticed a difference when I put them in my old 72 Z. Geez, that car came alive with just plugs. I have them in everything now..

**Salvatore** · #9 06-01-2007, 10:28 PM

Even your lawn mower?

@wot · #10 06-01-2007, 10:37 PM

OK, but then we're not using OEM Delco plugs. I agree that the Japanese plugs work better, I just hope the spark plug boots hide them.

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