bbc Dart 308 alum head spark plugs

[Mild Thunder]

I have some older dart bbc 308 aluminum heads. They are in my boat, with supercharger setup.

The plugs i removed were AR134. According to some charts i have seen, this isnt really a recommended plug because the reach is shorter(.460)??? Should i be going to a .750 reach plug? Compression only about 8.5:1. Plus most bbc dart heads seem to call for gasket style plugs? Are mine oddballs? Thanks!

[69Merc]

Hey Mild Thunder, welcome to the board!

If your castings are older than 1999, our aluminum heads were machined for a
.460 reach and a tappered seat. The maching program was changed in mid 1999 to accept the .750 reach with a gasket.

hope this helps!

[Bad Influence Racing]

I would also run a colder plug in this application due to excessive heat from cylinder pressure, the blower and constant rpm being in a boat. Keep an eye on gap as well. The "wind" being forced into that chamber from the blower tends to want to "blow out" the plugs like kid blowing out candles on there birthday. Tighten 'em up to about .030"-.035".

[Awesome Bill]

I have some older dart bbc 308 aluminum heads. They are in my boat, with supercharger setup.

The plugs i removed were AR134. According to some charts i have seen, this isnt really a recommended plug because the reach is shorter(.460)??? Should i be going to a .750 reach plug? Compression only about 8.5:1. Plus most bbc dart heads seem to call for gasket style plugs? Are mine oddballs? Thanks!

No your heads are not odd balls. Most of the older heads require the shorter seat plugs, and they were upgraded because of thread damage from people using all the muscle and thinking they had to torque them down extra tight! We have some older, very good, 320 fully ported Dart heads on our nitrous engine and we have to run that plug. We use a 9 series NGK or a AR132 plug while on the 600hp 2 stage unit and we never get the spark blown out!

I have never heard of a blower causing the spark to be blown out? I really don't think this is or will be an issue with your combination. How much boost are you running?, bet is is not much being you have to run pump gas, but either way, I would be running the 7 series NGK or AR135 gapped @ .035" blowing the spark out, I think both valves are closed when the spark or power stroke happens any way.

[Mild Thunder]

No your heads are not odd balls. Most of the older heads require the shorter seat plugs, and they were upgraded because of thread damage from people using all the muscle and thinking they had to torque them down extra tight! We have some older, very good, 320 fully ported Dart heads on our nitrous engine and we have to run that plug. We use a 9 series NGK or a AR132 plug while on the 600hp 2 stage unit and we never get the spark blown out!

I have never heard of a blower causing the spark to be blown out? I really don't think this is or will be an issue with your combination. How much boost are you running?, bet is is not much being you have to run pump gas, but either way, I would be running the 7 series NGK or AR135 gapped @ .035" BLOWING THE SPARK OUT WOW, I think both valves are closed when the spark or power stroke happens any way. Maybe if you were running top fuel or and alky blown engine you might need another mag! I apologize for some of these guys with the stuff they come up with.

I run 5psi of boost. I have MSD marine 6m ignitions, with msd pro billet marine distributors and blaster coils. I been running the ar134 plugs for 2 seasons, and they all look great. No signs of anything bad going on. Nice dark tan color. I guess i will keep running them. Any advantage by using a NGK 7 series?

[lun40119]

Do you notice with the NGK's that they almost all come very tight? I am using the pliers type of gapping tool.