so ive read on numerous sites that the plug to go with on a slant six is the NGKZFR5N, which i put into my 73 b200 van. i read to gap them at .040 and .045 so i did .043.

but! i feel that ive lost power, and my van is running sluggish. did i gap them incorrectly? should i switch back to the champions?

thanks!

I'm wondering if the rest of your ignition system is up to par. Wider gaps require more voltage and if the system is weak a wider gap may not be workable. Also, don't overlook the simple stuff. You may have a loose plug wire.

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Joshua

Did you cut the metal washers off of the plugs? You need to do that.

I'd do that, gap at .035 and go from there. If it doesn't run right after that, you probably have some other problem like Josh suggested. After you get it running right, then gap to .040 and see if it feels any different.

Just to build on this, I've never seen it explicitly stated anywhere so I'll ask here. I have a 1980 slant 6 225. I am getting the NGKs today and I am supposed to leave the washers on the plugs, right?

Hi krytellan, and welcome to the forum!
The heads on a 1980 model is a later model that came in 1974, commonly called 'peanut' heads. They use a different spark plug with a konical tightening surface without any washer. Use NGK UR-4 on the newer heads, be careful not to overtighten.

Olaf.

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Aspenized

Washers off! Q: What is Snoop Doggy Dogg's favorite restaurant?
A: Sizzler.

1975.

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

Sorry Dan, I made a miss!

(maybe I was half right, and the heads came late 1974 for the 1975 models??)

Olaf.

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Aspenized

If you go to the "Frequently Asked Questions-Electrical" section & look at HEI Electronic Ignition Retrofit How-To you will find in the first picture a diagnostic scope comparision between voltage amplitude between the .035 & .045 plug gap openings.

That test was repeated several times & showed that voltage amplitude doubled when the gap opened up. The voltage went from 5000 to 10,000 for that setup illustrating that a heavier demand was placed on the ignition system wires, coil, cap, rotor, etc. with a .045 plug gap.

Perhaps your system may have one of those elements not capable of carrying the extra voltage?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/