Decent Plugs

[TOMT]

Hi guyz, I,m tryn to find some plugs?? What we have been running on just the motor ( no Nos) are Autolite 4052, These are what our engine builder recomended, now seeing we are in Kiwi Land they are not that easy to get on short notice.
Now I have tried to cross ref these to NGK but have come up with nothin, So this is makin it quite hard to try and get some colder plugs for the Nos.
Any suggestions????

[John_Heard]

From what I can find a Autolite 4052 is a 14MM, .750" Reach, .8125" hex, gasket style, non-projected tip plug that crosses to a NGK BR9EVX - must be a platinum tip?

Can you use the smaller hex like the .6125" dia? If so you can probably use the same gasketed plug that most aftermarket racing heads use, they have the same thread size, 14mm and .750" reach only the hex is smaller. The NGK part numbers for those are R5671A-8 (cold) or R5671A-9 (colder).

Note: Some automotive stores may only be able to order these by the NGK Stock Numbers which are

Stock Number 4091 PN R5671A-7
Stock Number 4554 PN R5671A-8
Stock Number 5238 PN R5671A-9
Stock Number 5820 PN R5671A-10

-7 heat range is good for motor only naturally aspirated, -10 is cold for use for say a 400 shot and above.

[TOMT]

Hey there John, Cheers for the info I will see what I can get on this side of the sea....
We run Brodix Track2z so the NGK fittment shouldnt be a prob, just that we are wanting to step up the Nos and I have tried a 225 hit on these plugs but they were pepperd. And seeing we cant just get the Autolites at the local parts shop......
So what are your thoughts on the Ngk???
Will they be OK in this type of situation??

[John_Heard]

NGK is what I use most of the time, the equivalent Autolites are ok, but they cost more. Those NKG PN's are probably the most often used racing plugs for Nitrous.

You're probably going to want to use the -8 heat range for your 225 shot. When you see those black specks that's a sign that you have too much timing in it.

[TOMT]

Hey there, lolol well tryn to get a plug like that here is a joke!!! I can get a R5671A-10 but they are like $25 each...
I went to this link. www.ngk.com.au an they had a cross reference to the Autolite 4052 and came up with NGK B9ES. Now that seem to be rather cold for just on the carb dont u think???
If it is cold then as you say I need to pull more timing out. We have only ever just pulled out what the NOS chart says. I,m picking that the engine builder may have suggested these 4052z cause he new we would run the bottle, and not know . Now by finding this Forum I,m learning so much more!!!
We have been running Nos for 15yrs here and have had to learn by mistake, as no1 really knows that much over here and wat they do know I wouldnt trust. lolol

[John_Heard]

$25 - I think I would do some shopping around, that's way too high. Should be around $2 ea here.

See if they can get you an Autolite AR3933 or AR3934, that is an equivalent to the NGK 5671A-8 and is a good nitrous plug for the shot size you're talking about.

I'm not sure about that NGK B9ES, that's listed as a Motorcycle plug but has the right sizes to work, but have no idea about it's heat range though.

[TOMT]

Hey there John, they might be $2 in USA but were talking Kiwi here lololol Any sort of racing plug is like gold mate..
I know that the NGK range must differ once they get over here as the part numbers and listings all differ! makes it real hard tryn to get things sussed!
I am going to try the Autolites that I have and take more timing out of her, as we are only taking 4 deg out at the 175Hit. I have read and looked at the " Plug Reading" articles on this forum so will update after we can run her.
Say from your info can you tell me what heat range these Autolite 4052 are??? by crossing them to NGK they seem to me to fall into the 9 mark??? if so they are pretty cold for just on the motor?? Might exsplain why I can never get a really clean plug with no Nos.