Plug condition

[markmark2]

Hi all, any thoughts on engine/mixture condition from these plugs. One from each bank. Needles level with piston. Cheers Mark

[Motorsport Micky]

I assume you did a "plug chop" with these ? ie constant speed running about 50mph and then turned off the engine and declutched and rolled to a stop ? otherwise what would you expect them to tell you ?

http://kawtriple.com/mraxl/carb/plugchop.htm

Micky

[Arbman Al]

I assume you did a "plug chop" with these ? ie constant speed running about 50mph and then turned off the engine and declutched and rolled to a stop ? otherwise what would you expect them to tell you ?

http://kawtriple.com/mraxl/carb/plugchop.htm

Micky

I expect he was hoping that we could tell whether his carbs were running rich or lean, like most of us mere mortals would have thought. Why would he know about a plug chip, i didn't and I wouldn't mind betting a lot of others on here don't know about it either.

We don't all have your superior mechanical knowledge Micky.

[markmark2]

I expect he was hoping that we could tell whether his carbs were running rich or lean, like most of us mere mortals would have thought. Why would he know about a plug chip, i didn't and I wouldn't mind betting a lot of others on here don't know about it either.

We don't all have your superior mechanical knowledge Micky.

Hi Arbman, thanks for defending my request for help/advice. Actually I did do a plug chop......with chips and beans and very nice it was too. Note to self....cook chop slower next time. I'll consider myself severely reprimanded for asking such a stupid dumb-ass question. Wished I was clever.....

[tjk]

Hi all, any thoughts on engine/mixture condition from these plugs. One from each bank. Needles level with piston. Cheers Mark

A bit weak.

Tim

[Motorsport Micky]

Ooopps apologies for a clumsy reply.

Micky

[markmark2]

A bit weak.

Tim

Hi Tim, very nice of you to reply. Much appreciated. Mark

[wilf]

Very difficult to "read" plugs with unleaded fuel, nowhere near as good a gauge of mixture as with leaded.

[markmark2]

Very difficult to "read" plugs with unleaded fuel, nowhere near as good a gauge of mixture as with leaded.

Hi Wilf, thanks for the reply. They do look a bit lean so will make them a wee bit richer. Cheers Mark

[Andrew S]

Hi Mark, remember it's not a question of taking a plug from each head as each carb feeds 2 pots on each head. Best to take out 2 plugs next to each other so you can see which carb is doing what. You need to turn the mixture tool clockwise to enrichen

[markmark2]

Hi Mark, remember it's not a question of taking a plug from each head as each carb feeds 2 pots on each head. Best to take out 2 plugs next to each other so you can see which carb is doing what. You need to turn the mixture tool clockwise to enrichen

Hi Andrew, thanks for the reply. I forgot about that! I did take all the plugs out but it wouldnt let me upload 8 pics only 5. Could you refresh my memory as to what pots are feed by what carbs. Maybe 1 carb is a bit leaner than the other. Thanks again. Mark

[MandM]

May be of use to you Mark


Tuning the Stag Carburetors Using Colortune®
by Tim Buja, TKBuja@insightbb.com
Setting the air-fuel mixture using a Colortune involves replacing the spark plug
in one of the cylinders with the special Colortune plug. The Colortune plug has
a transparent window that allows you to see the flame color in the cylinder as
it fires. An overly rich mixture will have a yellow flame and will be
accompanied by black smoke (and noxious fumes) from the tailpipes. As you lean
it out to the optimum stoichiometric mixture, the flame color will change to
Bunsen blue. A mixture that is too lean will still have a blue flame, but the
brightness will decrease as the mixture is weakened. If the piston dampers in
each carb are working correctly, you should see the flame color change from blue
to yellow when you open the throttle, and then change back to blue as the engine
comes up to speed. Read the Colortune instruction sheet for full details on how
the system works.
In order to set the air-fuel ratio correctly, you need to know which carburetor
feeds which cylinder before you can start making adjustments. In this section,
all references to "right" or "left" are made when sitting in the driver's seat
looking toward the front of the car.
The Stag V8 engine is fed by two Zenith Stromberg 175CD SEV carburetors mounted
on a two-plane manifold. The right carburetor feeds the lower plane, which
connects cylinders 1, 4, 6, and 7. The left carburetor feeds the upper plane,
which connects cylinders 2, 3, 5, and 8. There is a small balancing passageway
that connects the two manifold planes, so you may see some small effects of
adjusting one of the carbs in a cylinder not directly connected to it. Be aware
that the cylinders in the Stag V8 are not numbered per the standard method (#1
at the left front), as illustrated in the figure below:
front of car
cylinder cylinder Key: L: Left Carb
l #2 #1 r R: Right Carb
r #4 R #3 l l: Cylinder fed by left carb
r #6 L #5 l r: Cylinder fed by right carb
l #8 dist #7 r dist: Distributor

Firing Order:
1 - 2 - 7 - 8 - 4 - 5 - 6 - 3
Note that the #2 (left front) cylinder is used to set the ignition timing, not
the #1 cylinder as in most other engines.
Colortune® is a registered trademark of Gunson's Ltd., Pudding Mill Lane, London
E15 2PJ

[73 Mimosa]

Carb to cylinder feed.jpg

[markmark2]

May be of use to you Mark


Tuning the Stag Carburetors Using Colortune®
by Tim Buja, TKBuja@insightbb.com
Setting the air-fuel mixture using a Colortune involves replacing the spark plug
in one of the cylinders with the special Colortune plug. The Colortune plug has
a transparent window that allows you to see the flame color in the cylinder as
it fires. An overly rich mixture will have a yellow flame and will be
accompanied by black smoke (and noxious fumes) from the tailpipes. As you lean
it out to the optimum stoichiometric mixture, the flame color will change to
Bunsen blue. A mixture that is too lean will still have a blue flame, but the
brightness will decrease as the mixture is weakened. If the piston dampers in
each carb are working correctly, you should see the flame color change from blue
to yellow when you open the throttle, and then change back to blue as the engine
comes up to speed. Read the Colortune instruction sheet for full details on how
the system works.
In order to set the air-fuel ratio correctly, you need to know which carburetor
feeds which cylinder before you can start making adjustments. In this section,
all references to "right" or "left" are made when sitting in the driver's seat
looking toward the front of the car.
The Stag V8 engine is fed by two Zenith Stromberg 175CD SEV carburetors mounted
on a two-plane manifold. The right carburetor feeds the lower plane, which
connects cylinders 1, 4, 6, and 7. The left carburetor feeds the upper plane,
which connects cylinders 2, 3, 5, and 8. There is a small balancing passageway
that connects the two manifold planes, so you may see some small effects of
adjusting one of the carbs in a cylinder not directly connected to it. Be aware
that the cylinders in the Stag V8 are not numbered per the standard method (#1
at the left front), as illustrated in the figure below:
front of car
cylinder cylinder Key: L: Left Carb
l #2 #1 r R: Right Carb
r #4 R #3 l l: Cylinder fed by left carb
r #6 L #5 l r: Cylinder fed by right carb
l #8 dist #7 r dist: Distributor

Firing Order:
1 - 2 - 7 - 8 - 4 - 5 - 6 - 3
Note that the #2 (left front) cylinder is used to set the ignition timing, not
the #1 cylinder as in most other engines.
Colortune® is a registered trademark of Gunson's Ltd., Pudding Mill Lane, London
E15 2PJ

Hi M, Thats a great help, thanks for taking the time to reply. I will get there in the end. Cheers Mark