question about spark plug gap?

[donkey_punch]

i bought a new set of plugs and wires. and they guy at the part store say that the motorcraft plugs that i bought were pre-gap. they were all between .50 and .55.
but then the ones that i took out of the car were at .35

so what should the gap be at? whats the stock gap, and would it make a difference since i have aluminum heads and a mild cam?

Thanks
Joe

 

[blksn955.o]

55 or so is the stock gap for the stock plug.

I would kinda want to make sure the plug is for the alum. head...he may have assumed you just need a stock plug that will not work with alum. heads in most cases.

Most people run a 35 gap with a higher compression, boost, or bottle to help stop spark blow out.

 

[juiced_94gt]

stock is .054 My tuner told me to gap mine to .040 for my combo in the sig.

 

[juiced_94gt]

55 or so is the stock gap for the stock plug.

I would kinda want to make sure the plug is for the alum. head...he may have assumed you just need a stock plug that will not work with alum. heads in most cases.

Most people run a 35 gap with a higher compression, boost, or bottle to help stop spark blow out.

Very true, sorry, my plugs are Autolite 3924's for the AFR's

 

[donkey_punch]

so is there a particular plug to use with AFR 165 heads?

thanks for the replys guys

 

[95opal]

so is there a particular plug to use with AFR 165 heads?

thanks for the replys guys

Autolite 3924's Seem to work for me.

 

[blksn955.o]

Alot of people have good luck with the autolite 3924's and such with alum. heads.

The plug diff. is that the stock plug is a tapper fit...look at were the threads end you will see an angle. That angle fits snug into the heads plug location. The alum. heads tend to need a gasket style plug. These plugs have a large flat area that has a "crunch" gasket or metal o-ring that seals it to the alum. head. Tapper fit plugs look like toothpics compared to the gasket style plugs that look like sumo wrestlers by comparo.

 

[HISSIN50]

I'd be sure to use antiseize with alum heads as well.

And yes, always check your gaps.

Good luck.

 

[donkey_punch]

thanks for the suggestion on the autolites

so i guess .35 is what i should gap them at?

and antiseize FTW. lol

thanks
Joe

 

[Don 95Vert]

We just today had a car on the dyno that was misfiring at higher RPMs. The plugs were brand new but we did not install them. We pulled them and gapped them at 0.035 - they were 0.055 and the problem went away.
Don