Spark plug/gap recommendations

[Daryl]

Greetings everyone! What spark plugs (and gapping) do you recommend for my ‘95 347 stroker? Brand? Series #?Gap for a stroker? Regular size or shorties?
And if this factors in: AFR 165 heads; Comp cam (specs in photo); Scat rotating assembly; BBK 75mm TB; MSD Performance Distributor; Screamin’ Demon coil; Accel 24lb injectors and MSD 8.5mm Super Conductor wires.

 

[Daryl]

Bump

 

[Terrorist 5.0]

Well the manufacture of the heads (AFR in this case) should specify the plug. Gap is dependent on some things, so each setup will require a different gap. I cannot personally recommend a gap, but research the cylinder heads. You may get an answer there.

Only alternative is wait for someone more experienced to chime in, or start experimenting.

 

[95opal]

Autolite 3924 @.054

 

[Daryl]

Autolite 3924 @.054

Thanks, 95opal! Took your advice, checked the AFR website and confirmed they specifically state the Autolite 3924. I went a cautionary step further and WAS thinking of opting for the AR3924’s (resistor) version but it turns out the 3924’s ARE a resistor plug.

 

[weendoggy]

Wow! Fairly large gap. I run AR3924 (race plug) in my 347 Cobra w/AFR185's and use a .035 gap.

 

[Daryl]

Wow! Fairly large gap. I run AR3924 (race plug) in my 347 Cobra w/AFR185's and use a .035 gap.

Yeah, I thought the .054 gap was pretty wide, too, but that’s what AFR recommends for NA applications

 

[95opal]

Wow! Fairly large gap. I run AR3924 (race plug) in my 347 Cobra w/AFR185's and use a .035 gap.

Gap really depends on ignition components and compression. You want to run the widest gap without misfire. .035 is what boosted or juiced guys will run, but for a 9:1 or so NA motor thats a pretty small gap.

 

[Mustang5L5]

Gap really depends on ignition components and compression. You want to run the widest gap without misfire. .035 is what boosted or juiced guys will run, but for a 9:1 or so NA motor thats a pretty small gap.

Was going to say the same. If you are N/A you should run the largest gap you can get away with without misfire. Stock plug gap is 0.052" to 0.056" so without any ignition upgrades that's likely where one should start.

I run Autolite 3924 at a 0.054" gap with my TFS170 heads. Runs great at that gap.

 

[ttocs]

do yourself a favor and when you take the first plug out, first thing to do is to compare it to the new ones to be sure they match. I got handed the wrong plugs and just assumed they were right and chased my tail on fouled plugs for months after that till I did compare them.

 

[weendoggy]

Gap really depends on ignition components and compression. You want to run the widest gap without misfire. .035 is what boosted or juiced guys will run, but for a 9:1 or so NA motor thats a pretty small gap.

I can say for 25+ years on my NA strokers, never ran it bigger. All good info though. My plugs have always read clean.

 

[Daryl]

do yourself a favor and when you take the first plug out, first thing to do is to compare it to the new ones to be sure they match. I got handed the wrong plugs and just assumed they were right and chased my tail on fouled plugs for months after that till I did compare them.

Actually did that on first and subsequent plugs on the Ram this afternoon. All matched and all looked good with the exception of #3 plug drivers side. But it was just a little gummed up not very bad though. Only got 1/2 way through replacing all 16. Will do passenger side tomorrow, which should be a tad easier because that brake booster won’t be in the way.

 

[Daryl]

I’ve been Googling around trying to determine if I should use a bit of anti-seize on the Autolite 3924 threads with my aluminum heads?

The majority of the responses say 2 things:
1. No, it affects torquing to spec; and
2. Not needed for “modern” spark plugs on first installation because they have a coating on them, but OK on subsequent R&R because the coating is only good once.

So what is it? And are Autolite 3924’s considered “modern”? (couldn’t find info if they came with the coating on the threads)

Cheers & thanks!

 

[weendoggy]

I can say, for over 45yrs I've put anti-sieze on every bolt/nut I replace. So yes, even the spark plugs. Remember Brylcreem, "A little dab'll do ya!"

 

[ttocs]

oh man, get ready!

 

[Daryl]

I can say, for over 45yrs I've put anti-sieze on every bolt/nut I replace. So yes, even the spark plugs. Remember Brylcreem, "A little dab'll do ya!"

Oh shit I’m old enough to remember Brylcreem, yes! LOL

oh man, get ready!
View attachment 47920

no kidding’… stuff gets EVERYWHERE! Gloves are 100% mandatory, even if you’re just putting one little dab on. Ask me how I know!

 

[Daryl]

I suspected so, primarily because dissimilar metals.

 

[badass98svt]

Yeah, I thought the .054 gap was pretty wide, too, but that’s what AFR recommends for NA applications

.054 is the stock gap for the 96-98 4V

 

[Daryl]

.054 is the stock gap for the 96-98 4V

What about a ‘95 5.0?

 

[ttocs]

I have to laugh a little every time I get out the anti-sieze because funny enough it reminds me of a trip I took to amsterdamn in the 90s when I was still a kid. Naturally we got ourselves a dime bag of some weed as we were only going to be there for 3 days, and then went back to our hostel to fire it up in the lounge as everyone staying there did. Now if any of you are old enough to remember weed in the 90s, it was normally hard as a brick from the long journey it had made, dried out like old fall leaves left in spring. This was the first time I had ever got my hands on anything fresh and in breaking it up it was so sticky that it kept sticking to anything I touched. At first I tried to brush it off my fingers, then my hands before I finally had to turn to my brother and tell him to help me knock it off my hands or we were not going to have any left. Every time I get out the anti-sieze it ends almost the same way.....