NGK vs. AC Delco spark plugs
 

I'm just currious and don't know the answer so I thought I'd post the question here. I've always used AC Delco plugs in my 70 Z28 with the stock LT1 engine. I've heard so much good about NGK plugs that I decided to try a set. My question is this....the electrode on the NGK is substantually longer than the AC Delco plug....will this cause any problems? The pictures below are an AC Delco R43, and an NGK XR5 V Power both of which are the correct plug for my application. Your knowledge is greatly appriciated!

http://i97.photobucket.com/albums/l2...n_DSCF0633.jpg

http://i97.photobucket.com/albums/l2...n_DSCF0635.jpg

Re: NGK vs. AC Delco spark plugs
 

The XR5 looks more like a R43S than a R43. On a Z28 the tip of the plug might touch the piston, if you still have domed pistons. You might want to see if you can cross reference the R43 plug and see if it crosses to something other than the extended tip XR5. Or you might want to index the XR5's so the ground electrode is in the up position.

Re: NGK vs. AC Delco spark plugs
 

I run R44S in my 69 Z and have no problems. You will know if they hit. The electrode will be closed. Is there an NGK chart I can use to cross reference AC Delco plugs to? Thanks, Sam

Re: NGK vs. AC Delco spark plugs
 

I think you will be fine. What I would do if you really want to be sure is put one in, disconnect the main coil wire so the car won't start and crank the engine over once. Pull the NGK plug out and check the electrode. If it does hit it shouldn't damage the piston like it would if you fired it up and ran it at a much greater rpm at idle..

I did this with my car just for my own peace of mind when I switched to the NGKs. They are great plugs and you will notice a world of difference..

Rich

Re: NGK vs. AC Delco spark plugs
 

Sam,does THIS help?

Re: NGK vs. AC Delco spark plugs
 

I always ran AC 43N sparkplugs in my L78. I couldn't find them when I went to get my car last year so I put the equivalent Autolights in it. Thought that was sacrilegious putting Ford plugs in a Chevrolet. Over the winter I found some NGK plugs that look identical to the 43N. They are B7ES. The heat range seven doesn't have the projected tip like the fives do. Maybe you could use the seven heat range in the shorter plug and it will match up to the old ACs.
Jim

Re: NGK vs. AC Delco spark plugs
 

My XR5's don't hit the pistons, and they work great!!

Re: NGK vs. AC Delco spark plugs
 

Do you run the XR5'S on the street or a heat range higher? I use R44S what would the NGK number be to that? Thanks!

Re: NGK vs. AC Delco spark plugs
 

Sam...I think the next heat range up is the XR4 for NGK. They are just the opposite of AC Delco...Delco the higher the number, the hotter the plug...NGK the lower the number. the hotter the plug.

Re: NGK vs. AC Delco spark plugs
 

Month+ old thread, I know....

My 70Z is a ~58K mile, original-build engine. Ran great for the last ten years with R45S, then switched over to 43s about a year ago. It doesnt care for those too much.

Thinking of putting some XR5s in it based on all the good reports, along with a new set of points which are probably 10 years old. Think the XR5s would be the correct plug, or should I step up/down a heat range considering it's never been rebuilt?

It'll still 4-wheel slide https://www.yenko.net/ubbthreads/imag...ns/naughty.gif , but isnt quite right at WOT https://www.yenko.net/ubbthreads/imag...ns/burnout.gif

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