bob58o
SuckSqueezeBangBlow
Five
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Help Reading Spark Plug
- Thread starter bob58o
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bob58o
SuckSqueezeBangBlow
Six
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bob58o
SuckSqueezeBangBlow
Seven
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bob58o
SuckSqueezeBangBlow
Ate
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bob58o
SuckSqueezeBangBlow
Nine
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bob58o
SuckSqueezeBangBlow
That's all folks!
https://m.youtube.com/watch?v=gBzJGckMYO4
https://m.youtube.com/watch?v=gBzJGckMYO4
bob58o
SuckSqueezeBangBlow
Some good stuff here
https://www.slideshare.net/mobile/J.T.A.JONES/carburetor-theory
https://www.slideshare.net/mobile/J.T.A.JONES/carburetor-theory
bob58o
SuckSqueezeBangBlow
Ok going for round Three.
No Muffler (Same as Previous)
0.0453" Main (10.88% more jet opening area)
0.026" Idle Jet (Same as Previous)
AR3911 Autolite Racing Spark Plug
I expect and want so see a larger and/or darker Air-Fuel Mixture Ring.
I think this will be close. The knowledge and experience makes the sacrifice of a few plugs (dollars) worth it to me.
I'll remember to check for the log/stall.
No Muffler (Same as Previous)
0.0453" Main (10.88% more jet opening area)
0.026" Idle Jet (Same as Previous)
AR3911 Autolite Racing Spark Plug
I expect and want so see a larger and/or darker Air-Fuel Mixture Ring.
I think this will be close. The knowledge and experience makes the sacrifice of a few plugs (dollars) worth it to me.
I'll remember to check for the log/stall.
bob58o
SuckSqueezeBangBlow
Top: This area is the idle circuit indicator. For a race engine, this area has no real application; race engines don't rely on the idle circuit the way a street engine does. However if you're tuning a street driven vehicle then this portion needs to be a dark gray/tan color. This is achieved by tuning the idle air/fuel ratio. This is done by changing the air bleed orifice size, changing the idle feed restrictions, adding or subtracting idle bypass air, or a combination of these things.
Warning Note: The initial timing has a direct effect on how much the primary throttle blades need to be opened to achieve a good idle. If the initial timing is insufficient, the transfer slot might be overexposed in an attempt to raise the idle speed sufficiently. An overexposed transfer slot will cause an noxious smelling, poor quality idle and poor off-idle response.
Middle: This is the area that will show the combustion chamber condition and air/fuel ratio at part throttle cruise (primary side only) with the power valve and secondaries closed. This is a high vacuum condition, vacuum advance will be fully activated. The mechanical advance may not be fully in. Usually about 30-50 MPH depending on the gear and weight of the car.
Bottom: This indicates the conditions at high load, low vacuum, open throttle settings. This is a priority if drag racing. Using a 5x or 10x scope you need to look right down to the bottom of the porcelain where it meets the metal body of the plug. This is the area that will have the color that you need to study and tune to. The other 2/3 of the porcelain will be burned clean by the high heat generated by WOT and high RPM, so cruise or idle characteristics will not show.
Warning Note: The initial timing has a direct effect on how much the primary throttle blades need to be opened to achieve a good idle. If the initial timing is insufficient, the transfer slot might be overexposed in an attempt to raise the idle speed sufficiently. An overexposed transfer slot will cause an noxious smelling, poor quality idle and poor off-idle response.
Middle: This is the area that will show the combustion chamber condition and air/fuel ratio at part throttle cruise (primary side only) with the power valve and secondaries closed. This is a high vacuum condition, vacuum advance will be fully activated. The mechanical advance may not be fully in. Usually about 30-50 MPH depending on the gear and weight of the car.
Bottom: This indicates the conditions at high load, low vacuum, open throttle settings. This is a priority if drag racing. Using a 5x or 10x scope you need to look right down to the bottom of the porcelain where it meets the metal body of the plug. This is the area that will have the color that you need to study and tune to. The other 2/3 of the porcelain will be burned clean by the high heat generated by WOT and high RPM, so cruise or idle characteristics will not show.
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Rich Mixture Ring 2.jpg
bob58o
SuckSqueezeBangBlow
Some good looking Main Jet Mixture Rings
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Good Mixture Ring 2.jpg
bob58o
SuckSqueezeBangBlow
Rich Mixture Ring
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Rich Mixture Ring.jpg
bob58o
SuckSqueezeBangBlow
Lean Mixture Ring
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Lean Mixture Ring.jpg
bob58o
SuckSqueezeBangBlow
So I think I wasn't even at full throttle.
Pedal to the floor had the butterfly all the way open when so one was sitting in the **** thing.
With me sitting in it, stationary,I don't think the pedal stop allowed full throttle.
When driving and the suspension is bouncing, the throttle could completely close.
This is probably why I had so much color above the main jet WOT Mixture Ring.
I tried the 0.0453 and ran out of gas.
I didn't run out, but it was low and the engine sputtered and died.
I looked at the plug. It looked speckled like detonation. Probably from running low on fuel at high rpm, full throttle.
I "fixed" my throttle issue by removing the pedal stop. Now my heavy foot makes up for the suspension.
When the swing arm moves, my foot makes up for it.
I tried again.
The mixture ring is wider but a light color.
The insulator is clean looking, but still speckled. Maybe from when I ran out of gas.
I want to try an even larger main.
0.0465"
HobbyTown USA
Then NAPA for 4 more plugs.
I like plug chops. Just need to learn to read the ring without cutting the threads.
Pedal to the floor had the butterfly all the way open when so one was sitting in the **** thing.
With me sitting in it, stationary,I don't think the pedal stop allowed full throttle.
When driving and the suspension is bouncing, the throttle could completely close.
This is probably why I had so much color above the main jet WOT Mixture Ring.
I tried the 0.0453 and ran out of gas.
I didn't run out, but it was low and the engine sputtered and died.
I looked at the plug. It looked speckled like detonation. Probably from running low on fuel at high rpm, full throttle.
I "fixed" my throttle issue by removing the pedal stop. Now my heavy foot makes up for the suspension.
When the swing arm moves, my foot makes up for it.
I tried again.
The mixture ring is wider but a light color.
The insulator is clean looking, but still speckled. Maybe from when I ran out of gas.
I want to try an even larger main.
0.0465"
HobbyTown USA
Then NAPA for 4 more plugs.
I like plug chops. Just need to learn to read the ring without cutting the threads.
michaelcorp
New member
Thats way to rich...
more fuel = more air = bigger explosion = black or dead plug.
plug should look more whitish that shows air/fuel are correct.
play around with air and fuel screws if you cant find a proper setting...(rather more air then fuel)
more fuel = more air = bigger explosion = black or dead plug.
plug should look more whitish that shows air/fuel are correct.
play around with air and fuel screws if you cant find a proper setting...(rather more air then fuel)
bob58o
SuckSqueezeBangBlow
Going off the coloration higher up on the porcelain? Then yes It looks rich, but watch this next run. Plug only had like 10 minutes if that.
No air screw on this one.
It's a gx390 carb.
I can insert wires into the air bleeds to make em smaller.
Let me get a good run with a new plug.
I'm going to go up in main jet size.
It will look better.
I don't think I was at full throttle.
That last one was 0.0453 or #115
I've got three bits that I measure at
0.0465"
0.0470"
0.0475
I've got three jets I can drill (if I redrill the 0.041")
My jets will be
0.042x
0.043x
0.0453
0.0465
0.0470
0.0475
Going to run the 0.0475" next.
I'm hoping this will be very close to perfect, if not just slightly rich at WOT.
ultralight01
Senior Yet Young Member
I'm gonna leave my spontaneous exploders here just to destroy this awful, misleading poll thread. CLOSEUP photos of the electrode next time, please.
Thanks, genius.
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Psyduck GIFs? ?!?!?!?!
bob58o
SuckSqueezeBangBlow
Next round will be WOT
0.0475-0.0480"
My calipers are not that good.
I'm labeling it 0.048"
I have to keep the kart going so the TC doesn't stall the engine far from home.
If it dies when I'm turning around. It's about a 1/3 mile push uphill. Not fun.
0.0475-0.0480"
My calipers are not that good.
I'm labeling it 0.048"
I have to keep the kart going so the TC doesn't stall the engine far from home.
If it dies when I'm turning around. It's about a 1/3 mile push uphill. Not fun.
bob58o
SuckSqueezeBangBlow
Here is my 0.048" Main Jet
Looks better to me. WOT looks about right. I THINK???
There are some specs on the insulator.
Not sure what I want to try next.
I might want to try the colder AR3910x again and see what it looks like.
It runs good now. No hesitation or bog. No stall when I floor it. No backfire or popping.
I think this looks about right on the main and feels right on the low jet.
BUT what about those specs?
Looks better to me. WOT looks about right. I THINK???
There are some specs on the insulator.
Not sure what I want to try next.
I might want to try the colder AR3910x again and see what it looks like.
It runs good now. No hesitation or bog. No stall when I floor it. No backfire or popping.
I think this looks about right on the main and feels right on the low jet.
BUT what about those specs?
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bob58o
SuckSqueezeBangBlow
No AND THEN!!!
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If it were me I would get 2 more jets and go 1 size up on each. But yeah it's really close now. Does it start easy ? I know when I drilled my pilot it will start without he choke now and idle. So I know its rich.
In this summer weather I woukd want it a touch in the rich side. It will run a little cooler also
In this summer weather I woukd want it a touch in the rich side. It will run a little cooler also
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