Dan,

I have seen how you reccomend the NGK ZFR5N and the Autolite 985.

I am kind of partial to Autolites.Autolite 66 are what I usually use.

Question:Can you explain to me the difference in the plugs,and if this is definitely a switch I should make.

Thanks
JZ

Here y'go.

I like the NGKs better; quality is nicer, tip design is more advanced and the suppressor is of a more modern design. Either the 985 Autolite or the ZFR5N NGK uses a 5/8" hex socket rather than the 13/16" socket you're used to using.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan,

Read the thread:

So I guess what you are saying is that these are a cleaner burning plug?

Thanks
JZ

The NGK's are a much cleaner burning plug. Mine see use everyday and are in fantastic shape for having over 10K miles on them.....no deposites of any kind.

Should the plug's "washergasket" be cut away on these NGK's too when having plugtubes. They seem to be longer in the picture, so that's why the question.

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Mopar or no car.

Bye the way, who the F**K is Tu Ning?

Yes, on a 1963-1974 cylinder head, remove the metal gasket ring. I don't usually cut them off, I grab them with pliers and unscrew them off the plug.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I notice NGK says the 13/16" hex is coded ZGR-5N...

If the peanut plug guys need a longer intrusion into the chamber then the TR-4 would be the long reach plug over the standard taper seat UR-4's the 1975+ head crowd and Chevy crowd uses...if they only made a ZTR-4 then we'd be in good shape, also.


-D.Idiot

Sounds like I will give the NGK-ZFR5N a try.

Little fyi: They are also listed as a NGK-3459

Have a good one.

JZ

Interesting -- good sleuthing! Wonder if those are popular enough to be generally available.
No books in front of me at the moment, can't recall what the "Z" designates.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Z=extended "gap"
T=Tapered seat 14mm 5/8" hex 17.5 mm reach
(I wish we could get the 'T-1' designation then same as above, but .807" reach)
R=Resistor
4/5 is the heat range (5 is colder)

N="special side electrode"

Too bad I don't see them as available in the copy of NGK's catalog...but the TR-4's are.... Just trying to see about getting something for us late model peanut plug guys....

-D.Idiot

I got some NGK-ZFR5N's today.I installed them in a spare head I have on the bench along with a Autolite 66.These plus extend quite a bit farther than the shorter plug.I understand this is probably the reason they fire or work better.

My question is: Is there any clearance issues with these plugs I should be worried about?

I am sure there isn't,just wanted to hear it.


Thanks
JZ

No problem, you are "clear" for takeoff.

Maybe if you have time, can you shoot a couple comparison pics of the 66 vs. the ZFR5N from the combustion chamber side? That would be a helpful couple of images to have, to convey the difference in how the plug fits/works.

Remember, no metal ring gaskets on the plugs with a '63-'74 head!

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have been meaning to take some pics of this head with the porting and such that has been done.I am not to good at the picture posting stuff however if someone has a e-mail I can send them the pics for them to post.

Ring gaskets have been removed.

One other thing:Do we know the heat range for these plugs.Is there a chart for looking up hotter and colder NGK plugs?

Thanks again

JZ

Heat range is more or less identical to the 66s you've been using. Heat range charts are in NGK's plug catalogue.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

What about 60-62 heads?

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