Best plugs for carb'd roller

forango · Nov 21, 2025

I have a 1989 5.0 roller motor with a Edelbrock cam(Basically E-cam I think), hi rise manifold and holley 4160 carb. The combo seems to run best at about 16º advanced timing (actually 18º but at that timing it backfires a bit after WOT out the exhaust)...The issue is that at the 16º it seems to still not be burning all the fuela nd you can smell the excess by the eng bay after running it for a while.

My thought process is that the plugs I have in it are crappy AND potentially not gapped properly for this setup....What is the suggestions for proper plugs and gap on this combo?

General karthief · Nov 21, 2025

Pull a plug or two and post a pic of it.

forango · Nov 21, 2025

General karthief said:
Pull a plug or two and post a pic of it.

Should I do a certain "test drive" prior to pulling them? I haven't driven it in a week not sure if that matters. LOL

AeroCoupe · Nov 21, 2025

What cylinder heads to you have?

forango · Nov 21, 2025

AeroCoupe said:
What cylinder heads to you have?

The heads I believe are factory heads but have been built with FMS valve springs and pushrods

General karthief · Nov 21, 2025

Just yank a couple plugs, let's see what they are and gapped and condition

forango · Nov 21, 2025

General karthief said:
Just yank a couple plugs, let's see what they are and gapped and condition

I will try and do that tomorrow..dealing with some health issues but I shoudl eb able ot ge tit tdone..thanks

AeroCoupe · Nov 21, 2025

I used to run Motorcrafts in stock heads. Believe they were ASF-42C’s gapped at 0.045.

forango · Nov 22, 2025

Plug #1 in firing order

forango · Nov 22, 2025

Plug#5

forango · Nov 22, 2025

Plug #7

forango · Nov 22, 2025

Plug #3...this is where it got interesting...in the 3rd pic you can see the porcelain at the boot was chipped but not completely off...I replaced with an Autolite 25 I had laying around...not sur eif that would cause a misfire or bad condition

forango · Nov 22, 2025

This is the tool I have for gapping...Not optimal I am going to invest in something better

forango · Nov 22, 2025

I am not sure why I gapped them at .050...They don't seem to be buring overly lean so maybe gap the new plugs tighter like .045?

forango · Nov 22, 2025

I am assuming the NGK UR45 V plug is the best option? Hard to find in my area but I fond a store that has them

forango · Nov 22, 2025

Also what would you guys recommend for good high performance plug wires? The wires on the engine were on it when I bought it so could use replacing likely..sorry for all the questions. LOL

AeroCoupe · Nov 22, 2025

Well the first f’n issue is the AC Delco plugs. Toss every damn one of them in the trash and install a fresh set of Autolite 25’s or the Motorcrafts I mebtioned earlier. Warm the motor up and make a pull it two and then check the plugs.

And for the love of god don’t put Champion plugs in it either. Those are for Mopars.

Noobz347 · Nov 22, 2025

AeroCoupe said:
a fresh set of Autolite 25’s o

Wut he sed.

forango · Nov 22, 2025

AeroCoupe said:
Well the first f’n issue is the AC Delco plugs. Toss every damn one of them in the trash and install a fresh set of Autolite 25’s or the Motorcrafts I mebtioned earlier. Warm the motor up and make a pull it two and then check the plugs.

And for the love of god don’t put Champion plugs in it either. Those are for Mopars.

OK so Autolie 25's over the NGK U45?

I only had these delco's in there because where I live finding decent plugs in a pinch is a PITA lol

Gap tighter like .045?

forango · Nov 22, 2025

Also, as far as making a pull or two, will it matter if I have to then go 25 through my hood to get home? LOL

Best plugs for carb'd roller

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wonder how much it would cost to ship you a pair

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lube between the nut and the face. I know my lubes

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wonder how much it would cost to ship you a pair

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lube between the nut and the face. I know my lubes

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lube between the nut and the face. I know my lubes

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