Best plugs for carb'd roller

Noobz347 · Nov 22, 2025

forango said:
Gap tighter like .045?

Start at 0.40 and go from there.

nickyb · Nov 22, 2025

Once you get the plugs in,a good set of wires for stock motors are the MSD Street fire wires, I like them cause you cut them to length.

AeroCoupe · Nov 22, 2025

Anything but copper core plugs on our cars are a waste of money.

I just run the Motorsport 9mm wires in black. Never have had an issue and don't have to cut to fit.

rednotch · Nov 22, 2025

All ways ran auto lite 24's in stock heads, though they call for 25's 1 heat range higher, 3924's if aluminum heads, stock ignition systems mostly gapped at .045 since almost every car had a nitrous kit on it at some point never had issues.

General karthief · Nov 22, 2025

You can do the 'two three pulls and check the plugs' thing if you feel but likely won't tell you much, JMO.
Yes the broke porcelain will cause the plug to short to ground, look at that boot and I bet there's a 'tracer' marking on the boot.
I will check my plugs (on a street car) after about 10k miles mostly looking for oil fouling.
The O2's (wide band gauge) can tell you lean or rich. Good tuning tool for a carb too.

forango · Nov 23, 2025

I am gonna grab the plugs today and try and install them int he weather holds

I also did not mention that I have a MSD ignition and blaster coil...The distributor is a stock type however..not sure if that affects choices or gaps

AeroCoupe · Nov 23, 2025

If you can bypass the MSD ignition and get the car back on the stock ignition. The newer boxes are known to have issues. Their coils are pretty much junk anymore as well. If you need a good coil then this one is pretty good:

https://www.oreillyauto.com/detail/c/blue-streak/standard-blue-streak-ignition-coil/std2/fd478/v/a/5471/automotive-car-1993-ford-mustang

I just remembered this is a carbed car so you cannot bypass the box so never mind on that.

forango · Nov 24, 2025

These are the pics of the new plugs A25's gapped at .045..I did some pulls but as I said getting back through my neighborhoof is about a 1/2 mile of idling....I did do a small WOT hit down our street then kille dit but was only a 1st gear hit and not very far....I will say that the engine wasn't quite as "peppy" as before and was backfiring out the exhaust again after the pulls.

forango · Nov 24, 2025

nickyb said:
Once you get the plugs in,a good set of wires for stock motors are the MSD Street fire wires, I like them cause you cut them to length.

I as actually going to buy those yesterday but the auto store i went to had a set of the same style Accel wires on clearance for ten bucks so I got those instead and will install this week sometime

AeroCoupe · Nov 24, 2025

Plugs look good with regards to the heat mark on the strap. Gasoline engines tend to have it closer to the threaded body of the spark plug where yours is. As clean as those plugs are it looks like you are running lean to me. I would think that the center electrode porcelain would have a little brown tint to it but yours is white.

There are other guys on here with way more experience at reading plugs than me so hopefully they will chime in. @FastDriver @Noobz347 @rednotch

FastDriver · Nov 24, 2025

Lean to my eye, and I'd take a degree out to try to center the temp band on the corner of the strap. Don't see any detonation there, yet, but that doesn't mean you won't get more in a higher gear.

I bought a nice little magnifying tool that lets you light up and magnify the inside of a plug's porcelain. So I'm told, that gives you a better way to see what's actually going on with the AFR.

Noobz347 · Nov 24, 2025

FastDriver said:
Lean to my eye

Yep

FastDriver · Nov 24, 2025

Actually, I reread what you stated, @forango, and after 1/2 mile idling back, I don't trust the AFR diagnosis. You really need to cut the motor off and pull the plug right away for accuracy. Also, what's up with the popping 'after' the run? Do you mean that you're popping due to going lean on decel? If so, don't do that when plug reading. There's no reason to care what it's doing when the load is that low.

General karthief · Nov 24, 2025

JMO but ain't run long enough to tell anything other than the mark on the strap which look pretty good to me.
Thing that concerns me is the pop'n on deceleration, now is it backfiring in the exhaust or just a little 'purpling' like little farts?
Tuning with a carb is similar to computers, a carb is just a mechanical computer, got a vacuum gauge?
Need to address the 'sluggishness' issue first, take a vacuum reading, write it down, timing with vacuum advance connected and disconnected making notes along the way.
post findings.

forango · Nov 24, 2025

FastDriver said:
Actually, I reread what you stated, @forango, and after 1/2 mile idling back, I don't trust the AFR diagnosis. You really need to cut the motor off and pull the plug right away for accuracy. Also, what's up with the popping 'after' the run? Do you mean that you're popping due to going lean on decel? If so, don't do that when plug reading. There's no reason to care what it's doing when the load is that low.

So the popping happens after a WOT pull and I am completely off the gas..about a second or so later it gives one good POP out the exhaust...It did this when I had the other plusg gapped at .050 and at 18º...then when I turned the timing down to 16º that went away until I put these plugs in at .045

That was why I assumed it was either running overly rich, or not burning all the fuel somewhere.

forango · Nov 24, 2025

General karthief said:
JMO but ain't run long enough to tell anything other than the mark on the strap which look pretty good to me.
Thing that concerns me is the pop'n on deceleration, now is it backfiring in the exhaust or just a little 'purpling' like little farts?
Tuning with a carb is similar to computers, a carb is just a mechanical computer, got a vacuum gauge?
Need to address the 'sluggishness' issue first, take a vacuum reading, write it down, timing with vacuum advance connected and disconnected making notes along the way.
post findings.

Yeah I really don't have anywhere around here to do a good WOT pull and then shut down and let it sit until it cools down to pull a plug...Unless with the iorn heads it is ok to pull the plgu while still hot.

forango · Nov 24, 2025

General karthief said:
JMO but ain't run long enough to tell anything other than the mark on the strap which look pretty good to me.
Thing that concerns me is the pop'n on deceleration, now is it backfiring in the exhaust or just a little 'purpling' like little farts?
Tuning with a carb is similar to computers, a carb is just a mechanical computer, got a vacuum gauge?
Need to address the 'sluggishness' issue first, take a vacuum reading, write it down, timing with vacuum advance connected and disconnected making notes along the way.
post findings.

As for the "sluggish" part it just didn't immediately jump to life when I mashed the gas like before I changed the plugs..and froma dead stop previous it would roast the tire, whereas after the plug change it just spun a little and then grabbed if that makes sense.

AeroCoupe · Nov 24, 2025

Base timing on most 302’s is around 12 to 14 degrees. You sure you don’t have the distributor off a tooth or a worn out timing chain? I just throwing stuff out but that seems to be a lot of initial timing to me.

General karthief · Nov 24, 2025

Or a bad balancer.
I'd deal with the timing, check balancer, make sure 0* on the balancer is TDC on the #1 piston, rotor at #1 on cap..

rednotch · Nov 24, 2025

Its a carb car, bit different for initial vs the efi stuff, what's it seeing full advanced, are you checking it with a decent dial back light or just setting initial, good way to see if the marks are off with a dial back light. How are you controlling the timing, threw the msd box or a vacuum advance or are you just running it locked with a stock type tfi distributor? Popping and farting on decel, make sure its got 0 exhaust leaks first, then Check rest of the ignition components. Backfire like bang, like can take out a muffler bang, definitely want to look at the carb too, might need a rebuild kit or rejet. A sub $100 wideband gauge with a good bosch sensor is a good investment.

Timing mark getting pretty close to the base of the strap. If your reading plugs for everything shut it off, pull over, swap a few of the old ones in and drive it back. Corners plugs if you don't want to do them all.

Best plugs for carb'd roller

Stangnet Facilities Maint Tech... Er... Janitor

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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

I was uncomfortably high & wearing a helmet

Stangnet Facilities Maint Tech... Er... Janitor

I was uncomfortably high & wearing a helmet

wonder how much it would cost to ship you a pair

Active Member

Active Member

Active Member

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

wonder how much it would cost to ship you a pair

I'd like to remain having one chocolate starfish

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