Which Spark Plugs are best??

thompsonsd · Feb 24, 2004

Here's my Spark Plug experience. I used to love Accel's because of the U groove. Then I went to Bosch Platinums for a few years. Then last Fall I rebuilt my 302 with all the stuff listed in my signature, and the Bosch cracked on me. A set of brand new Bosch went into my rebuild, and I kept having problems, until I discovered that a couple of my new plugs had cracked causing the running problems....

So here's my question to our collective: Which plugs do you recommend???

TrophyHead · Feb 24, 2004

Autolite 24's.

87gtconv · Feb 25, 2004

Autolite 3924 per AFR

Fivocapri · Feb 25, 2004

87gtconv said:
Autolite 3924 per AFR

what about stock heads ?

i had tr55-1 based on what the guy at the parts store told me.
they were running hot. they were blistering the ceramic not bad but...
i ordered a set of tr6's to see how they work. they are one range colder.

Until i got them i went ahead and got 2544's for the stock heads for the time being. they wok great. if they look like they should after a few tank fulls i may just keep them in there.

87gtconv · Feb 25, 2004

I run Motorcraft ASF42 on my stock head engine! Gap at .054"

NeQX · Feb 25, 2004

For those aluminum heads, autolite 3924

thompsonsd · Feb 25, 2004

I thought the Platinum type plugs were the best? Aren't Autolites the flat electrodes that you need to change every couple of months to maintain the best spark from them??

warmdye · Feb 25, 2004

NeQX said:
For those aluminum heads, autolite 3924

What about iron?

muddslide · Feb 25, 2004

What about aluminum heads with a blower/supercharger?

schiccc · Feb 25, 2004

87gtconv said:
I run Motorcraft ASF42 on my stock head engine! Gap at .054"

what about gt40p heads

Mustang5L5 · Feb 25, 2004

thompsonsd said:
I thought the Platinum type plugs were the best? Aren't Autolites the flat electrodes that you need to change every couple of months to maintain the best spark from them??

Says who? The Autoparts store guys? Platniums are the worst plug. Copper plugs are a much better conductor of electricity than platnium is. Platnium plugs are only for old guys in caddys who want to go 100K miles without changing plugs (even though the plugs will deteriorate at around 30K miles)

For stock heads, Autolite 25's or Motorcraft 32C's

Electricity takes the path of least resistance so all those double prong, splitfire and u-groove plugs are pointless. The spark will just jump to one side and not do a thing to the other.

WHat you want to do is take the plug and ground the strap down til the end is centered over the electrode. Then round (not point) the tip of it. Takes about 2 mins to do to each plug...and they last a bit longer than 2 months.

91lxvert · Feb 25, 2004

preach on mustang5L5!

platinums require more voltage to fire as well so stock ignitions will actually sometimes loose power with platuinum it may be minute but it is some.

i have also seen vehicles fail emisions that run splitfire or the like.

and even with a high capacity system a copper plug is still better due to being able to fully maximize the current going to it.

when i bought my car it had bosch platinums (worst plat plug you can get, NGK and Acdelco are much better) i left them in due to the guy had just changed em two months down the road i developed a random misfire, traced it down to the plug switched em for motorcraft stockers not a problem one.

thompsonsd · Feb 25, 2004

I've seen some great feedback so far! I've also seen some questions from guys with Iron heads and guys with power adders. Anybody have some good info on those??

Also, to recap so far, we all seem to agree I had been making a mistake with Bosch... It also looks like you guys suggest Autolite 3924 for aluminum heads. Anybody disagree or have other info??

So far this has been a Great thread! Thanks to you all for the inputs!

90stangLX302 · Feb 25, 2004

Since there are already a few posts on here about sparkplugs and i don't want to start another one,...what plugs should be used on GT-40P's

final5-0 · Feb 25, 2004

I have used Autolites in various types of iron heads and run them now in my AFR's.

Used them for years and have worked great with no probs.

Later
Grady

bock · Feb 25, 2004

Fivocapri said:
what about stock heads ?

i had tr55-1 based on what the guy at the parts store told me.
they were running hot. they were blistering the ceramic not bad but...
i ordered a set of tr6's to see how they work. they are one range colder.

Until i got them i went ahead and got 2544's for the stock heads for the time being. they wok great. if they look like they should after a few tank fulls i may just keep them in there.

The Ford OE spark plugs.

Mustang5L5 · Feb 25, 2004

90stangLX302 said:
Since there are already a few posts on here about sparkplugs and i don't want to start another one,...what plugs should be used on GT-40P's

Stock plugs for a 93-95 Cobra....

Autolite 764's or Motorcraft stock replacement (i forget if it's 42c's or 32c's...but it's one of those)

HemiChallenger · Feb 25, 2004

Platinum, and platinum + garbage and all that crap are a joke. The best plugs are the cheepo motorcraft or other similar normal correct heat range spark plugs. Platinum is for vheicles that you dont want to change the plugs in for 100,000 miles, that's why manufactures use them, and even then they never last that long. The gap has a lot to do with the plug though as well. Another problem with platinum plugs is you CANNOT gap them, because is scrapes off the platinum. I run the $1.25 a piece motorcraft plugs in my car and that's the best thing for it.

thompsonsd · Feb 25, 2004

Ok, here's what I got from Airflowresearch.com. They recommend the "Autolite 3924" for their Heads. As was mentioned earlier, thanks! Now this leads to another question....

I've seen a lot of "Platinum" bashing this thread... but I've also seen this Autolite "Platinum" plug suggested a few times. Sooo.......... ??

kndyblucapri · Feb 25, 2004

Dude autolite or accel are probably the best to use

Which Spark Plugs are best??

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