[Speargun]

Looking for a second opinion from the spark plug gurus in here. I "think" I know what's going on, but not sure.
What do you see here?

These plugs are out of an aluminum IA-II, Speedmaster heads, 10.8:1 SCR, and street driven on 92 octane.
Base timing is 18* btdc, total timing is set at 34*, but will get up to 38ish at cruise.
The Edelbrock Pro-flo 4 dpfi doesn't like the 4.5" - 5" of vacuum at idle so I run idle AFR kinda fat.

Note: There are only 2 different plugs in these photos. One of the plugs has a bit of water on it and kinda looks like melted aluminum under zoom.

[lust4speed]

Looks like a couple points too hot on the plug and a little too rich.

Compression might be too high to run 34° but not sure from just looking at the plugs.

[steve25]

How does your timing go up to 38 when cruising if your total is 34?

Do you have vacuum advance?

[Speargun]

"How does your timing go up to 38 when cruising if your total is 34?"

The Pro-flo ecu is controlling timing and can add advance when the vacuum is high.

[Speargun]

Here's what I'm thinking...

1) It looks to me that the base timing mark is too close to the end of the strap.
2) I don't see a total advance mark on the strap anywhere, which leads to
3) It looks like the heat range, color change, is 7 or 8 threads down.

My guess is that the plug (NGK BKR5S) is (way) too hot of a plug and I should back it down to a 7 or 8 heat range.
I've run heat range 6 or 7 plugs on previous iron block/aluminum head 10.25:1 builds with good results. Since this is an aluminum block/aluminum head build, I was advised to run a hotter plug. (I'm beginning to think I got some bad advice.)

Which heat range would you suggest?
(NGK = 1 is hottest & 10 is Coldest)

[ta man]

7's or 8's. The so called timing mark is also affected by plug heat range.

[chiphead]

The fat idle AFR is throwing the plug reading off. The plug looks way rich, which throws off reading the strap because the carbon starts to cover the heat mark on the strap. And you don't know how much of that carbon on the insulator is from idling and how much is the actual WOT mixture. That's why they say not to idle when trying to read plugs.

Put a new set in, give it 2-3 WOT rips and shut it down. Then pull 2 plugs on each side and see what they look like. If you think you've got salt and pepper on the insulators, you need to slow down the curve so it doesn't come all in before 3000 RPM.

If you go 2-3 heat ranges colder, it's may start to foul plugs. It's going to be a balancing act to keep the plugs clean if your idle AFRs are in the 10s or 11s.