Any experience with E3 spark plugs?

[OrtonvilleBob]

Anyone in the group have experience using E3 brand spark plugs in their flathead? The specific plug recommended for our engine is E3.52. There's lots of hype online both pro and con but I've yet to see anything posted from someone that has actually evaluated them in a vehicle equipped with a vintage, old-school 6 volt electrical system.

[Bloo]

I tried about 3 different brands, but not those. I imagine they are fine. There is not going to be any great advantage to any particular brand of spark plug. The bigger issue is that many brands have discontinued some heat ranges and then lumped all their recommendations onto whatever was left in production.

 

I'm using AC LM-46 in my 1936 208 Flathead. They are lawnmower plugs. The "46" heat range is close to the originally recommended AC K-7, but slightly hotter. AC superseded the K-7 to AC-45 in 1937 if I remember correctly. The LM-46 are non-resistor, and have short insulators and unplated bases like the K-7 did. The short insulators are not an advantage, They are a disadvantage if anything because they could theoretically arc over easier. They sure do look the part though. They are burning fairly clean with no signs of overheating. I think I'll stick with them.

 

If you try the E3 plugs, be sure to let us know how it goes.

 

[OrtonvilleBob]

Bloo, thanks for the info. I've subsequently decided to give the E3 plugs a pass. When I contacted their "tech support" department about my specific application the reply was pure marketing hype with a link for "where to buy". My concern is that the E3 is a fixed gap design. Since the gap spec for a Pontiac flathead is only .025" I was concerned the E3 plug might be based on the more common, wider .035-.040" gap used in other applications. Would a stock '53 ignition system be strong enough to jump the E3 gap during crank when available coil voltage is the weakest? Not even acknowledging the question was a turnoff for me. I'll stick with NGK,

[Bloo]

I am running the gap at .040 on a stock coil on my 36 six. I know that isn't right according to the book. It has been my experience that wider gaps (like .035) tend to run a little smoother on more modern cars that originally ran a .025 gap.

 

The most important thing a larger gap does, bad or good depending on how you look at it, is raise the voltage the coil rises to before it fires. This is harder on insulation, like the cap and especially the rotor. Also the coil itself, and to a lesser extent the spark plug wires and the short insulators on my spark plugs. Also there is a limit to how much voltage the coil might be able to provide, and the engine needs more under heavy load. It might not be able to do it. The spark might just go away on a hard pull.

 

On my car I was most concerned about the coil surviving, but after hearing that some of the early 6 cylinder Chevrolet enthusiasts were running .040 with no trouble, I decided to try it. Their coils came from the same source as mine. The gap has been at .040 for a couple of years and one really long trip and nothing bad has happened. I don't know how your 1953 coil would do, but I suspect it would be fine.

 

24 minutes ago, OrtonvilleBob said:

Would a stock '53 ignition system be strong enough to jump the E3 gap during crank when available coil voltage is the weakest?

 

Good question. I don't know. 6 volt cars have no way to compensate for the drop in battery voltage while cranking, if the starter drags the voltage too low it might not fire. My car has huge battery cables and cranks like crazy, so it hasn't been an issue for me, but it might be for someone.

 

Edited June 15, 2022 by Bloo (see edit history)