spark plug ?

[flattie]

I'm running a 6-71 mooningham with Merlin heads and 2 750 dbl.pmp carbs with a msd ign. Which spark plugs should I use?
http://us.f1.yahoofs.com/users/dacf806f/bc/pictures/DSC00289.jpg?bcDnfB9ApCCzDfeR

[BradP]

Spark plugs?
If you start that thing it's just gonna get dirty!

[mister460]

Copper core Autolites or something like them. Platinum plugs last a little longer but for the most part they're just a gimmick. Plug gap is more important than type. And a lot of high po ignitions actually recommend NOT using gimmick pl...I mean platinum plugs.

[Heatseeker]

What heat range and plug gap should I run? I have a mild 454, 8-71 BDS, 2 850's, Mallory Hyfire ignition, Comp 9000 unilite, Promaster coil(Save the cracks,I've already heard all about Mallory products and carrying a tow rope! I'm stuck with what I've got for now.). Any suggestions are appreciated!
Thanks in Advance!!!

[Infomaniac]

Sorry I cannot recommend a specific plug. I cannot remember exactly which NGK I am running. I will look tomorrow. Autolite was recommended. They are good plugs but are very difficult to read because they are black. Run these after you get it jetted right. Platinum is very resistant to fouling due to combustion deposits. It is hard for deposits to stick to. They are good if you run it extra rich just to be safe.
Run a cold plug for sure. One common misconception about plugs is the heat range. A hot or cold plug is actually the operating temperature of the plug. I has nothing to do with the energy of the spark. What determines that is the gap and type of ignition source. The correct plug needs to be hot enough for combustion deposits to not foul it and also be cold enough to not cause pre-ignition. A high performance engine has high combustion temps so it needs a cold operating temp plug.

[VD CRUISER]

In my 547ci with 1071 and 2 1050 dominators and MSD ignition Merlin heads I just run the cheap Autolites,heat range 24 or 25 and they seem to work just fine. They last a whole season.

[Heatseeker]

VD Cruiser,
What gap do set the plugs to. I bought a set of Autolite 25's last week, and they came with .060" gap. Good or not?

[VD CRUISER]

I set mine at .045 with the MSD #6. A wider gap would probably be ok as long as it didn't cause a miss.

[Heatseeker]

Thanks. I'll start there!

[stressedout]

Run a autolite 24 set at 35. We have run autolites for many yrs. no problems. Autolite also makes a race plug that is J gapped, ELECTRODE IS CUT BACK these are only for high energy ignitions.

[Slick]

Flattie,
Maybe you didn't see my post on one of Bill's topics, but I think you should start by turning those zoomies around. They're backwards, man. That or you did a helluvajob putting that blower on the wrong way.

[gnarley]

Originally posted by Slick:
Flattie,
They're backwards, man. That or you did a helluvajob putting that blower on the wrong way.
Backwards if it's a jet or an I/O but since his name is flattie I'd bet it's a V-drive yah know...

[bruleracer]

ngk, heat range #9

[MrHavasuCat]

I am running a 510, 8-71 blower and MSD 6 ignition. I gap the plugs at .035.

[Boater Bill]

Well, I don't run a blower but know a little about plugs so here is my $.02. I think Merlin recommends a .460 reach, tapered seat plug, for gas applications. I've run and liked Delco R42TS plugs which are "cold" and extended tip. Have also run equivalent in Autolite and am now running NGK's. Still getting some time on the NGK's to determine if I like them. Delco's seem to last longer than Autolites for me. I'd like to add to Infomaniac's post that the heat range is not the operating temp, but the amount of heat the plug "removes" or dissipates from the combustion chamber. A cooler plug dissipates heat faster. Heatseeker, don't listen to the cracks about Mallory, I run an ign setup similar to your and I love it all the way to the bank! Also, forget about the gap as they come out of the box, always regap plugs! A good rule of thumb when adding a spark box (Mallory/MSD etc) is to set gap at factory setting then increase .002 at a time till your boat slows down, then go back. Seems like most who posted are running .035, thats where I am at also at the moment, running clean, but I'm still working on my tune-up. Too big of gap or worn plugs will give a mis-fire at high RPM's, that is where plugs are "loaded" most heavily. Hope this helps.

[blowncarrera777]

heatseeker i run a mallory hifire in my blown carrera and no problems at all, so i aint spending the$ for msd unless needed. I run ngk cant remember type number but i run them at about 30 gap, just change them more often.