Re: NGK vs. AC Delco spark plugs
 

The pics you posted show two different types of plugs, one is a projected nose, the other is not. If you don't want a projected nose, and can't find a NGK "normal" cross reference, go to a racing plug if you can find the right heat range. I use a cold NGK racing plug in my L78, and they work fine. They are a .460 reach.

Re: NGK vs. AC Delco spark plugs
 

Update to this whole story...I put in the NGK XR5's and they run great...after Marlin's post I wasn't too worried because he has the same engine in his Deuce as I have in my 70 Z28. Bottom line, so far from how the car runs with the NGK's, I like um! https://www.yenko.net/ubbthreads/imag...iggthumpup.gif

Re: NGK vs. AC Delco spark plugs
 

Those NGKs are great. I switched out the hemi and the 455HO to NGKs from Autolites and it was a noticeable difference.

Listen for yourself:

455HO with Autolites:

http://i287.photobucket.com/albums/l...h_S7001338.jpg


455HO with NGKs:


http://i287.photobucket.com/albums/l...h_S7001389.jpg

Re: NGK vs. AC Delco spark plugs
 

i took my 68 Z out for the first time this spring with set of the NGK XK5s and the car ran perfect. Car seemed to rev up quicker with the NGKs.

Re: NGK vs. AC Delco spark plugs
 

Picked up some XR5s this afternoon, and theyre a gold cad type color rather than the silver in the pics above. https://www.yenko.net/ubbthreads/imag...lins/frown.gif

Could probably live with the silver, but dont think I can handle the gold https://www.yenko.net/ubbthreads/images/graemlins/no.gif Think I'll scuff, mask, and put some hi-temp black on the area that shows while I'm going through the distributor.

Re: NGK vs. AC Delco spark plugs
 

[ QUOTE ]
The pics you posted show two different types of plugs, one is a projected nose, the other is not. If you don't want a projected nose, and can't find a NGK "normal" cross reference, go to a racing plug if you can find the right heat range.

[/ QUOTE ]
If you don't want the projected tip, you could go with a YR5 / 7052 (same as UR plug except w/ non-projected tip)...

Re: NGK vs. AC Delco spark plugs
 

Don't know if this will help -


http://i158.photobucket.com/albums/t.../Rocket046.jpg
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http://i158.photobucket.com/albums/t.../Rocket047.jpg
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Re: NGK vs. AC Delco spark plugs
 

I swapped out my Delco R43T for NGK UR5 last year and it really gained some get up & go.. https://www.yenko.net/ubbthreads/imag...ns/burnout.gif