Doc Holiday wrote:Here is a plug from my engine after a nitrous pass. Let me see if I have this right. Where the brown ends on the ground strap is my heat mark, correct?
Yup, looks like it in that picture.
Doc Holiday wrote:So, since its so high on the strap, that means I should try to add a couple degrees of timing, right? I'm shooting for the heat mark to be about where the strap meets the base if I understand correctly.
This is where you start watching closely what you're doing, yes it might be able to take 1 or two degrees more, however I'm not all that familar with those plugs or that type of engine. I don't think I would put much more in it from where you're at. Maybe try 1 more and see how the car performs. Most people recommend stopping at the curve on the ground strap (in reference to the plugs in the earlier pictures). Some will chase it a bit more past the curve if the car responds to it, but got to remember you're on the upper end of how much timing you should be running at that point. If you see black specks show up, take timing back out.
Doc Holiday wrote: I'm not sure how to tell if the plug looks lean or not though. My thoughts is that it looks good, but I'd thought I'd throw this picture on here to get a second opinion. This is using C16 gas. Whats the verdict? How do I know if the plug is too cold or too hot?
It looks pretty darn close on the plug heat range, the center porcelin is nice and clean, so it's getting hot enough to burn off any deposits there, but it's not hot enough to melt the glue around the center electrode or get any damage to the electrode. The C16 doesn't color a plug a lot so it's kinda hard to tell from the picture, but I don't see any signs of it being rich at all - you do however need to look down at the base of the porcelin to see what the fuel ring looks like.