What spark plugs / gap for twin turbo + cammed setup?

gw77

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Hey all,

Long story short I've got an 88 RX7 with a 95 Mustang GT 5.0 motor that I don't know a ton about. Giving it the once over this spring with some new belts / plugs / wires / fluids / etc and could use some guidance.

Car has a twin GT35R setup running 5psi. I was also told it has a "built top end" (springs/retainers) and a BC Stage 3 cam. (I can definitely hear the cam so that much is true.) It also has an MSD distributor.

I come from turbo Focuses (MK 1.5), Subarus, and RX-7s (rotary) so not quite sure what the norm is in terms of what plugs to run, especially on a modified setup like this. My go-to on those platforms is typically the "one step colder" NGK iridium option.

Is that the move here? And if so does anyone have the part number? Thanks a million for the help.
 

badass98svt

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That 302 will never survive on a stock bottom end. I'd worry about that first before plug gaps.

I have a turbo on my 4.6 4V but unfortunately doesn't doesn't help you with your 302 specs. Sorry I can't help more.
 

duh09

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1 step colder and a tighter gap is the starting point. I am spitballing off the top of my head, but I'm pretty sure around a .028-.034 range is a good starting point.

What are you using for tuning? Timing and a good balancer will be the deciding factor on how much abuse the SBE will take. There are plenty of good high hp cars on SBE with modern ECUs and tuning.
 

95opal

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Aluminum heads?
duh09 pretty much nailed it.
Autolite 3924 or 3923 gapped at .028
And go from there.
 

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