Spark Plugs

Thanks Kevin - I was pretty sure that was the case. This is the second time in a week I have seen 24/25's mentioned for alum heads, which just did not seem right as far as I knew. I brought that same question up on the other thread and the poster stating to use 24's never repied back.
But since I dont know about all alum heads, I figured I was missing something.
 
No problem JT. I have had several cars with aluminum heads as well as working on a few of my friends cars with aluminum as well.

One time a friend tried to use some 24's and stripped the head.:bang:
He didn't know about it either.
 
Some will work OK with up to .053-.054. Each car responds a little different due to different ignition systems. Mine have always been safe and worked good with .045. Even when I had an MSD 6AL.
 
I gap mine the same as Kevin, though some like to nitpick that decision. If you do gap it at .054" or more, and find the ignition cutting out at higher revs, you can upgrade the ignition or close the gap. My ignition supports 0.056" but I still run at 0.046". Just a personal preference.
 
I find stock gap works well with mine..but honestly I've never tried anything else. I really question people when they say this type or that type did or didn't work..I think most every plug on the market today will work decent, wether they are plat's Vgroove, indexed, or plain old autolights...but that's just my thinking.
 
Ok, I think I figured it out. As stated earlier, the 24's have a shorter reach, only .460 inch. The 3924 has a . 750 inch reach. The Autolite 64's that I'm using also have the .750 reach, but use a 13/16 hex instead of the 5/8 hex
 
DMAN302 said:
I find stock gap works well with mine..but honestly I've never tried anything else. I really question people when they say this type or that type did or didn't work..I think most every plug on the market today will work decent, wether they are plat's Vgroove, indexed, or plain old autolights...but that's just my thinking.

I think most plugs will work fine - BUT - the fact that this set of heads calls for a plug that will extend it's spark deeper into the combustion chamber than stock or iron heads is where my thoughts are - i think that if my bosche platinums reached far enough in, i'd leave them in, but they are just stock replacements -
 
On that note, I am not a fan of Plat plugs in EFI 5.0's. Plat does not conduct nearly as well as copper (annealed). Some folks notice a diminished idle and high RPM cut out with plats. Since 5.0 Plugs are relatively accessible, running copper (which suffers more gap erosion than plat) plugs is a good decision.

Plus, one has to be very careful when gapping plats (a drag-style gapping tool that scrapes the ground strap and electrode can scrape the plat off).
 
DMAN302 said:
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.



I was having no issues with the old plugs. They were less than a year old.

I pulled the car once, it made 289 HP.

The shop tuner asks me what plugs i was using, i told him regular autolites.

He told me use 3924s, we install them and make a pull. I made 302.4 rwhp..


Simple as that.
 
i was running NGK plugs and they fouled pretty quick..my engine running extra rich might be why..but i then swaped them for the cheap autolites from walmart 3923 and they work great