Spark plug reading

-
71Demon540

71Demon540

Well-Known Member
Joined
Jan 21, 2023
Messages
936
Reaction score
1,930
Location
Connellsville, PA
Pulled #1 and #6 plug after 3 runs to see how the tune up looks.

Timing mark looks good on the ground strap. And the fuel ring looks as good as I have ever had.

That is an out of the box APD 1175 on race gas that was built specifically for my engine combo.

Can’t be unhappy about that. Today I will be racing at Keystone so hopefully it proves consistent.

IMG_4943.jpeg


IMG_4946.jpeg
 
71Demon540 said:
Pulled #1 and #6 plug after 3 runs to see how the tune up looks.

Timing mark looks good on the ground strap. And the fuel ring looks as good as I have ever had.

That is an out of the box APD 1175 on race gas that was built specifically for my engine combo.

Can’t be unhappy about that. Today I will be racing at Keystone so hopefully it proves consistent.

View attachment 1716409335

View attachment 1716409336
Click to expand...
Looks like what I look for on my spark plugs.
6 might have a little more fuel but looks good too me. Safe and not rich.
 
Newbomb Turk said:
It’s pretty fat at WOT.
Click to expand...
Will have to respectfully disagree on that. But after I posted the photo I realized how the photo looks little different than in person. But regardless, the car is very consistent and I’m happy with it. Especially for an out of the box carb which usually come MUCH richer than this one did. It was money well spent. Especially after going 5 rounds today only moving .02 dealing with wind.
 
71Demon540 said:
Will have to respectfully disagree on that. But after I posted the photo I realized how the photo looks little different than in person. But regardless, the car is very consistent and I’m happy with it. Especially for an out of the box carb which usually come MUCH richer than this one did. It was money well spent. Especially after going 5 rounds today only moving .02 dealing with wind.
Click to expand...


How wide is the fuel ring around the porcelain?

Anything over .100 is fat.
 
71Demon540 said:
Ill have to measure it
Click to expand...

I’m not saying to change it. If you race where you get big DA swings I run them fat.

A little fat helps because when the DA goes up (unless it’s a couple thousand feet or more in a short time) the extra fuel won’t hurt the ET much.

But when the DA swings the other way and you start getting Disneyland DA numbers the car will repeat better fat than if you were very close at the higher DA.

In other words, going from a tight (close to lean) tune up at high DA to a low DA where you go real lean will change the ET far more than if you go from a little fat to a tight tune up.

Carbs are a self tuning device. It does a better job going from fat to leaker than lean to real lean.
 
I agree that for an NA deal you’re rich. Enough that stripping fuel out of it might pick up ET. But if you’re happy with how it runs and how safe it is then there ya go.
 
Can you post closer pics of the ground strap please? From the one you posted timing is soft as well.
 
TT5.9mag said:
Can you post closer pics of the ground strap please? From the one you posted timing is soft as well.
Click to expand...
Ya it was really hard to take a good picture of the ground strap as my stupid phone wouldn’t focus in enough. My adopted step dad and I looked at the plugs and he does my engines and he was fairly pleased with the plug reading.
Since I have a grid. I do intend to try some different timing as all I have to do is plug in my laptop to change timing.

Same thing with my dad’s roadrunner. We have been doing too many other things with his car to try different timing yet.
 
71Demon540 said:
Ya it was really hard to take a good picture of the ground strap as my stupid phone wouldn’t focus in enough. My adopted step dad and I looked at the plugs and he does my engines and he was fairly pleased with the plug reading.
Since I have a grid. I do intend to try some different timing as all I have to do is plug in my laptop to change timing.

Same thing with my dad’s roadrunner. We have been doing too many other things with his car to try different timing yet.
Click to expand...
Most people like to see the timing mark in the middle of the bend. I have found that to be soft for best power. I like the ground strap to be colored all the way to the base. That’s where I’ve noticed adding more timing stops making more power.
CAVEAT: you cannot be octane limited
IMG_1309.png
 
As far as fuel ring width, all I can do is give you a correlation to something ive done. This plug (same plug as above post) was from a turbocharged big block. Fuel ring was .105 wide and was reading 11.8-12.0 for the whole pull on some of the most accurate o2 software there is.
IMG_1310.png
 

You must log in or register to reply here.
-

Similar threads

Demonx2
Appreciate some input on spark plug reading
2 3 4 5 6
Replies
125
Views
10K
Bewy
B
4spdragtop
Spark plug reading
2 3
Replies
59
Views
6K
TT5.9mag
TT5.9mag
Kendog 170
Spark plug article
Replies
6
Views
1K
4spdragtop
4spdragtop
T
My engine wiring harness burned up a couple wires yesterday!
2
Replies
41
Views
3K
timk225
T
T
No spark
Replies
11
Views
543
67Dart273
67Dart273
Back
Top Bottom