Spark plug reading

[RLF Cuda]

I consider leak down values within 10% of each other very good. There are many reasons for cylinders to show different leakage including variation in ring location and alignment which can change over time. The most important thing to listen for is valve leakage and then head gasket leakage. I wish there were a way to pressurize the intake manifold to check for intake gasket leaks, but I haven't found a good way to do that yet.

 

[Newbomb Turk]

Thanks, I noticed the "rounded" areas. Wasn't sure if they were like that new or not. Or if that was an issue. I'm new to analyzing plugs lol.
Timing is not locked out. 18* BTDC, no pinging.
Thanks.

Interesting. How much total timing is that?

I’m asking because it looks short on total.

Also, if you look at a new plug you can see how sharp and clean those edges are.

I’m not saying the plug is raging too hot but it’s close to being plenty warm. Adding in a bit more total may end up making that plug too hot.

You are managing the heat the plug sees and fuel and timing also affect plug temperature.

 

[4spdragtop]

Thanks, that's all I know right now on timing. I haven't dug into the tune too much yet.
I will try to get numbers and report back.

Interesting. How much total timing is that?

I’m asking because it looks short on total.

Also, if you look at a new plug you can see how sharp and clean those edges are.

I’m not saying the plug is raging too hot but it’s close to being plenty warm. Adding in a bit more total may end up making that plug too hot.

You are managing the heat the plug sees and fuel and timing also affect plug temperature.

 

[4spdragtop]

Here's initial timing

 

[oldkimmer]

Steve, what rpm r u cruising at? Have u had it at a steady cruise for at least 50kms 1 way? Kim

 

[4spdragtop]

I'm kinda spitballing, but approx 55mph and 2300rpm? I can pay better attention next time lol.

Steve, what rpm r u cruising at? Have u had it at a steady cruise for at least 50kms 1 way? Kim

 

[Hysteric]

I still think it's running rich(by smell) but other than that I think it's running pretty well.

That can also mean it's lean at time of ignition at the spark plug and that would correspond with clean plugs and electrode wear.

Just because you give a cylinder an AFR of 12.5 to 1 doesn't mean that's the AFR at the plug when you fire it.

Shrinker on electrode wear:

I dont know anything about the engine but the photos appear to show a slight rounding of the corners of the center electrode. At the very least there appears to be a clean zone on the corners. If this is the case then its likely that the mixture is insufficiently vaporized at ignition time. When the atmosphere is low in gas content around the arc location the oxygen burns the metal of the centre electrode. And it usually does this on the edges because thats where the electricity runs. Sometimes this deterioration is reduced by using a more powerful ignition.

 

[4spdragtop]

Thanks, I googled "Shrinker plug reading" and got this racingfuelsystems-Shrinker on Spark plug reading
I clicked on the link inside the forum but can't bring up Shrinkers pdf? Are you able to.post or link it?
Thanks!

That can also mean it's lean at time of ignition at the spark plug and that would correspond with clean plugs and electrode wear.

Just because you give a cylinder an AFR of 12.5 to 1 doesn't mean that's the AFR at the plug when you fire it.

Shrinker on electrode wear:

I dont know anything about the engine but the photos appear to show a slight rounding of the corners of the center electrode. At the very least there appears to be a clean zone on the corners. If this is the case then its likely that the mixture is insufficiently vaporized at ignition time. When the atmosphere is low in gas content around the arc location the oxygen burns the metal of the centre electrode. And it usually does this on the edges because thats where the electricity runs. Sometimes this deterioration is reduced by using a more powerful ignition.

 

[Hysteric]

I've posted it here before somewhere. Just watch these:

Carby Tuning Techniques

 

[TT5.9mag]

The ngk 4 is a hot plug. Looking at your pics it appears to be holding too much chamber temp. I like your previous plug choice better. The 6 or maybe even a 7 would be better. And you need a degree or two more total timing IMO for best power. If you’re confident in the tune up, go make a few hard acceleration runs. Then leak it down and read the plugs, that includes cutting one open.