Spark plugs

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38 Dodge

38 Dodge

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OK I went out and purchased new plugs for my slant. I picked up NGK ZFR5N's and so now when I compared them to my old plugs they are about 1/2" longer then the old ones and in this forum it is said to cut off the gasket I just want to make susre that I dont tear anything up before I get started. This is going in my 67 slant it has the spark plug sleeves.
So someone please let me know I not screwing this up.
 
I'm worried about the plugs being too long and hitting the pistons?
 
Not gonna happen. PO probably threw whatever in there and were not correct to start with. I'm running them in mine right now and I'm sure you have seen that these are the suggested plugs elsewhere on the forum. They need to be that long to reach the best area for the spark to ignite the mixture. Dennis
 
The ZFR5N spark plug does have a longer electrode than the standard slant-6 plug, but nowhere near long enough to hit anything in the combustion chamber. It is also nowhere near ½" longer. If it appears that much longer, then it is because whatever plugs were in there before are incorrect (too short). Go ahead and remove the metal ring washers, gap the plugs correctly, and install them.
 
Thanks for the info, I installed them and just went out and fired it up seems to run smoother. Now if I can just get the carb and timing worked out I will be good to go.
 
Hope you don't mind if I ride the coattails on the same subject here. I ordered the:

NGK Spark Plugs 3459 - NGK V-Power Spark Plugs

that are supposed to be a replacement for the NGK ZFR5N.

Those OK too? Got them from Summit.
 
slantsixdan said:
3459 is the US stocking number for the ZFR5N. It's not a "replacement".
Click to expand...

OK, well, that's what it said when I ordered and found elsewhere online... "replacement" (probably just generic website text I was seeing). So obviously the answer to my question then is that they're fine.

Ah yes, I see on the Summit site, it says NGK # "ZFR5N". Thanks.
 
would these plugs work for the later models?

also since the 75 up doesnt have the spark plug tube
would i be correct in assuming that you would leave
the compression ring on the plug for proper seal?
 
wp23n said:
would these plugs work for the later models?

also since the 75 up doesnt have the spark plug tube
would i be correct in assuming that you would leave
the compression ring on the plug for proper seal?
Click to expand...

Yes, and leave the seal rings on for the non drool tube engine, I could tell a big deference when I did my 66 /6 :cheers:
 

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memike said:
Yes, and leave the seal rings on for the non drool tube engine
Click to expand...

No. The '75-up heads without spark plug tubes use taper-seat spark plugs completely different from these gasket-seat plugs; the ZFR5N does not work in '75-up heads. The taper-seat plugs for the '75-up heads do not come with (or require) any kind of a seal ring or washer.

The only slant-6 heads with which you leave the metal ring washers on the spark plugs are the '60-'62 heads.
 
update,
I would recommend this to anyone. I cannot believe teh performance differance.
Thanks FABO for all the advice
 
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