what is a good plug to run on the street and occasional track with msd ignition indy ez 1 heads 10.1 compression 850 mighty demon carb.

Engine Masters spark plug episode:

https://www.youtube.com/watch?v=Ft6YOBjd5FE

It doesn't make any difference.

Robert

I take that back. No performance difference, but I use Iridium plugs because their advertising seems solid. They last longer.
RT

NGK-6987 is a good street plug for aluminum heads. It is an OEM plug used by Jeep, Ram and Chrysler on various engines. Usually easy to find and not too expensive. It has a projected tip and an extra wide gap.

I too saw that episode. Lots of hype about spark plugs dis-proven.

I would like them to due an episode with fuel additives.

i am currently have champion c59cx first time running these plugs they are a racing plug and wasnt schure they we're fit for street duty. i've allways relied on champion plugs due to the fact i had a racecar with 440 engine and 915 heads and wanted to try a cheaper plug and went with autolite installed them and the engine wouldnt even crank the second time and bought some more champion and went racing with them.

They did one on different types of gas. Race gas vs pump gas. The race gas was just a hair higher but basically no difference. Back in the day all i used Champion, But after having to replace them constantly(fouling) I switched to Autolites. Way better than the Champs. And yes i tried different heat ranges. The rare earth plugs may be an option over copper with a MSD6A. A "race" plug doesn't have any resistance so it may provide a better spark but you will get RFI

I will have to look for that episode. I to use Champion spark plugs.

I had WestTech dyno and help set up my EFI on my Cuda. Great guys.

Some of our younger members may not know about resistors spark plugs and non resistor spark plugs.
Resistors spark plugs were designed to stop ignition spark radio interference years ago, pre 1950 maybe They have air gap in the center electrode to make the coil go to a higher voltage before jumping both gaps in those spark plugs
The coil will only make enough voltage, spark, to jump the gap on each signal to fire,, if you have a bad plug wire that will allow the spark to jump to ground it will do that instead of jumping the gap on that plug especially at higher RPM and WOT

Same goes for resistor wires and copper core wires.

I run NGK iridium and never an issue. Been using for years since autolites went to Mexico.

A long time ago, I was in the "cold plugs for racing" cult. Always seemed like the first pass was a throw away to get the plugs clean from warm ups. idling around, etc. So we started going up in heat.

Ended up with a street plug (54/64-55/65 or 3924 Autolite). Much cleaner, sharper, consistent, no fouling. This was a healthy iron head 11:1 small block on good gas.

Same with gaps. .035 and fugedda bout it.

Those non resitter Autolite spark plugs have been great for a lot of years I love them

Back in the day - late '60s through early '80s, I guess - the "warm-up" plug deal was a thing on serious race engines.
Ignitions - possibly excepting magnetos - have improved since then, as have carbs.
Since then, I've used Champion, Autolite, & NGK on a variety of street stuff & race stuff, and can't recall any issues I could blame on a brand name.
In recent years I've mostly stuck with Champions because I have the heat ranges in my head.
NGKs appear to be a higher quality, in terms of finish & appearance.
The better metals (platinum, iridium) seem to last longer, which I chalk up to OEM/EPA considerations.
My last drag car ran C61Y or C59Y Champions (13.0:1, Alum head SB, 110 race gas, MSD6), mostly the 61s - 63s were a bit hot.
I found warm-up plugs in that combo weren't necessary.
Champions in N9-N12 range have worked fine for my street SB & Hemi cars, which have run MP electronic or MSD6 boxes.
I've noticed improved starting & running using an F150 epoxy coil on the MSD cars, which were cammed up - the MP box cars have been fairly mild to stock.

Here is my recent experience with fouling spark plugs: I recently bought a '75 Yamaha RD350. Great little bike but it fouled the recommended NGK BR8HSs left and right. Often within 30 miles. Some could be reused once after I glass beaded them, but most were shot. Wouldn't run again after an initial fouling. Made a LOT of adjustments to the bike and reduced the fouling significantly, but it still liked to foul them during a cold start.

The NGK Iridiums were touted on a number of the 2 stroke forums. So I ordered some to try. They were much slower to foul and could be cleaned repeatedly with the glass beads and ran fine after. I have only used 3 of the 4 that I bought. And all 3 still run the bike fine. Now, with a few more adjustments, the fouling is just about under control. So, my conclusion is that in this instance, the Iridiums were worth several non Iridiums back to back in the same engine that had fouling problems.

The B8HS NGKs were about $4.50 each. The BR8HIX Iridiums were about $8.00 each. Clearly in my application they were worth much more than the difference in cost. No performance difference, but a huge difference in what they would tolerate in the engine.

Iridium plugs are highly recommended for EFI engines. We use them all the time for EFI race engines. They are kind of spendy for carb engines unless the carb is really dialed in.