Spark Plugs

[Paul Perreca]

I am running bosche platinums in my Eddy AL RPM heads, and i was told that these do not poke far enough into the combustion chamber, and that I was supposed to use AutoLite 3924's - Now, is this true and is that the right number autolites, and if so, what should the gap be set at - someone said he gained considerable power because the spark plugs were wrong in his car, n he had the same type setup as me -

Thanks!!!

 

[srothfuss]

Autolite 24's sounds right.

Stock plug gap is 0.53 (?)
Most people run in 0.45 range

 

[RsStanG1987]

Bosch plugs suck balls get some autolites.

 

[FORCED2DV8]

Bosch PLatinums do not work very good, I have had better succes with autolites or NGk is my new favorite.

 

[86mustang5.oh]

weird my autolites fouled ou tin 2 months now have bosch still running strong oh well i got nothing...

 

[Paul Perreca]

yea but w/ the aluminum heads, i think the bosches aren't going intot he chambers far enough, thats why i was told to get the autolite 24's, and i was also told this would actually give my car alot more of the potential it has because the bosches were holding me back

 

[Mike92GT]

I've been using Autolite 64's in my Edelbrock heads for years w/ no problems. Not sure what the difference is between the 24 and the 64. I usually gap them around .045, but I think I have them at even less then that now since I added the blower

 

[Paul Perreca]

whats the diff guys! lol

 

[gwhiz50]

Tried all the fancy plugs but the autolite 24's have worked the best.

 

[Dbeck002]

I have dyno proof that changing those plugs to 3924s will pick up 15 rwhp.


I dynoed my car with regular plugs and then we swapped out to autolites since my numbers seemed low. Well that was the easiest 15 hp i ever made.

 

[HISSIN50]

Do guys run 20 series plugs in alum heads? I always thought that 3924's, 764's, etc were used in alum.

 

[Paul Perreca]

yup just picked them up from pep boys, my buddy works there, it was 10 bucks for all 8 lol if i just got 15 horsepower for 10 bucks, i'll **** myself - anyway - what is the recommended gap for my setup - N/A - i want 300 horses so bad i can taste it - i'm gonna tune it as best i can myself, than i'm gonna have JD performance take over from there, for another 800 damn dollars lol

 

[04sleeper]

DO NOT USE 20 SERIES PLUGS ON ALUMINUM HEADS!

They are not deep enough for aluminum and have less thread on them.

You need to use 3924's. The "39" means longer thread. (About twice as long as the 20 series.) The "24" after the "39" is the heat range of the plug just like the regular 20 series plugs.

The reason why you use the longer thread on aluminum is so it has more teeth so you don't strip the threads.

 

[04sleeper]

I would try around .045 for your gap. You should be good there.

 

[Paul Perreca]

thanks thats what i'm gonna gap it at i think - will the gap make a big difference? those 3924's are the ones i just got - the go farther into the combustion chamber right?

 

[04sleeper]

thanks thats what i'm gonna gap it at i think - will the gap make a big difference? those 3924's are the ones i just got - the go farther into the combustion chamber right?

The gap will make a big difference if it is way off, not too much if its a little. I have had Edelbrock, TFS and AFR heads and all worked best with .045 for me.

Yes, the 3924's are longer and go into the combustion chamber more.

You will notice a difference in the car when you put them in.

 

[Paul Perreca]

how big of a diff going from bosch platinum crapnums lol ahh i'll just post cuz i'll put them in within the week

 

[04sleeper]

Well you let us know how it works out for you.

Remember to use antisieze compound on the threads and don't over tighten.

 

[Paul Perreca]

what if i didn't use antiseize? lol

 

[DMAN302]

Always use antisieze when installing spark plugs into aluminum heads..result could be a bond between the two that's not easily broken. As for difference in plugs I would not expect any difference unless your having significant problems as is. Dbeck likely was having some significant issues prior to the plug swap and as a result did see a significant gain..though 15 HP is likely not going to be "felt" all that much..on a dyno the graph will look MUCH better. Get the 3924's Paul they are the recomended cross # for the Champion plug that Edelbrock actually specs for the heads...just that champion plugs are not really popular with the ford crowd.