Spark Plug Reading
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Spark Plug Reading
Ok...I've had the plugs in for about a year-Have probably driven car 4k w/ these plugs. Engine has about 8-10k on it.
I pulled number one plug after the Hot Rod Power Tour (about 2k of driving in a few days) Plug looked great-tanish color to it.
Car has been smelling rich lately with no changes since trip a year ago except a Carter electric fuel pump(Built-in reg 5-7PSI)-Which I put on the car right after the trip. But no noticable smoke or oil usage.
Plugs one, three, four and eight look a little rich- but then most of the driving recently have been stop and go- no real highway. However... two(the worst), five , six and seven have a BUNCH of crud-hard carbon on them. Why on these plugs and NONE on the others?
Engine is a hyd rolled 327 (about 240 duration) -RPM performer-Brodix Track 1 Alum heads w/ a Speed Demon 575 mechanical-MSD 6 w/ a Petronix II.
These are Autolite 405 plugs-I think I gapped them at .035
Ideas???-I'm going to pull the carb and re-adjust butterflys. It does have the idle-eze adjustment.
THANKS-Richard
I pulled number one plug after the Hot Rod Power Tour (about 2k of driving in a few days) Plug looked great-tanish color to it.
Car has been smelling rich lately with no changes since trip a year ago except a Carter electric fuel pump(Built-in reg 5-7PSI)-Which I put on the car right after the trip. But no noticable smoke or oil usage.
Plugs one, three, four and eight look a little rich- but then most of the driving recently have been stop and go- no real highway. However... two(the worst), five , six and seven have a BUNCH of crud-hard carbon on them. Why on these plugs and NONE on the others?
Engine is a hyd rolled 327 (about 240 duration) -RPM performer-Brodix Track 1 Alum heads w/ a Speed Demon 575 mechanical-MSD 6 w/ a Petronix II.
These are Autolite 405 plugs-I think I gapped them at .035
Ideas???-I'm going to pull the carb and re-adjust butterflys. It does have the idle-eze adjustment.
THANKS-Richard
Race Director
Joined: Sep 2002
Posts: 10,362
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From: San Diego - Deep Within The State of CONFUSION!
Wow you seriously need to get that car tuned on the dyno. Or at least install an air/fuel mixture gauge so you know how/where the carb is running!
IdleEze won't cure that the carb needs to be rejetted I believe. Also, that looks like oil on 2,5 6 - it's not just a rich carb. My .02
IdleEze won't cure that the carb needs to be rejetted I believe. Also, that looks like oil on 2,5 6 - it's not just a rich carb. My .02
Last edited by SanDiegoPaul; Apr 27, 2006 at 12:25 AM.
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
MarshRay-
No, it's not oil- the flash on the camera made the carbon look shiney.
Yes-three does look lean. I'm just stumped at why 3&4 look like they do-and the others are cruded up. It's a dual plane manifold...?
The car on the Hot Rod Power tour got almost 18MPG-
So-I guess I will have to get it on a dyno-
No, it's not oil- the flash on the camera made the carbon look shiney.
Yes-three does look lean. I'm just stumped at why 3&4 look like they do-and the others are cruded up. It's a dual plane manifold...?
The car on the Hot Rod Power tour got almost 18MPG-
So-I guess I will have to get it on a dyno-
Race Director
Joined: Nov 2000
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From: Waterloo ontario Canada
Originally Posted by Kalway
WHat happened to 6, too? 3 and 4 look a bit lean, too.
I would like all plugs like #3
Pro
Joined: Nov 1999
Posts: 520
Likes: 5
From: Front Range
I agree, #3 looks decent, i was always taught a plug like that looks perfect, tan or gray half way back on the anode, fading to black at the base.
Did you pull these immediately after a WOT run, or did you let the car idle before shutting it down?
If you pull the carb, follow demon's instructions for setting initial butterfly position, exposure of the idle metering slot (can't remember if that's what it's called), and take note of your current needle positions (adjusting screws).
If you're certain that you're not burning oil through the rings or valve guides / stem seals, then i agree with the opinion you might invest a few hundred bucks in some dyno time, you may need to re-jet. get someone who can shove a wide band O2 sensor up your tailpipe (
by someone who's certified to shove things up your tailpipe that is) and they'll give you the answers your looking for.
Did you pull these immediately after a WOT run, or did you let the car idle before shutting it down?
If you pull the carb, follow demon's instructions for setting initial butterfly position, exposure of the idle metering slot (can't remember if that's what it's called), and take note of your current needle positions (adjusting screws).
If you're certain that you're not burning oil through the rings or valve guides / stem seals, then i agree with the opinion you might invest a few hundred bucks in some dyno time, you may need to re-jet. get someone who can shove a wide band O2 sensor up your tailpipe (
by someone who's certified to shove things up your tailpipe that is) and they'll give you the answers your looking for.
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Racer
Joined: Aug 2002
Posts: 289
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From: Albuquerque NM
ooomph!
2, 5, and 7 dont look good at all.....stem seals or bad intake gaskets! If it was a carb issue they would be uniform across the board and not random. Any other thoughts on this?
Last edited by VetteLS6; Apr 27, 2006 at 12:38 PM.
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
Larry,
That was my thoughts-if it WAS the carb then the plugs would all look the same. I'm seeing the guy that built the motor tomorrow and see what he thinks. I'm thinking intake gasket too.
"Did you pull these immediately after a WOT run, or did you let the car idle before shutting it down?"
I didn't really think that would make a difference because that carbon didn't just get on the plugs. The plugs have black bases-so that might be kind of misleading.
I've pulled the carb- the butterfly position looks like where it's suppost to be. So...new plugs and I'll do a highway WOT run them check the plugs again.
That was my thoughts-if it WAS the carb then the plugs would all look the same. I'm seeing the guy that built the motor tomorrow and see what he thinks. I'm thinking intake gasket too.
"Did you pull these immediately after a WOT run, or did you let the car idle before shutting it down?"
I didn't really think that would make a difference because that carbon didn't just get on the plugs. The plugs have black bases-so that might be kind of misleading.
I've pulled the carb- the butterfly position looks like where it's suppost to be. So...new plugs and I'll do a highway WOT run them check the plugs again.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
Well maybe I'm missing something here, but from what I read, you drove the car 2k miles with no mixture problems, replaced the fuel pump and are now running rich and fouling plugs. Is it just me or is everyone ignoring the obvious. If your fuel pump is putting out too much pressure, it could unseat the carb inlet valve, overfill the float bowl and cause the carb to vomit fuel. Such improperly introduced fuel could easily distribute itself unevenly between the cylinders. You may need a fuel pressure regulator valve. Just my 2 cents worth. God bless, Sensei
Safety Car
Joined: Dec 2004
Posts: 4,071
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From: San Diego CA
Originally Posted by norvalwilhelm
I don't agree with 3 and 4 being lean. I like how they look. After a run you should see how white my plugs are and yet plugs last forever and on teardown after 6 years the piston tops were clean and no sign of burning.
I would like all plugs like #3
I would like all plugs like #3
Thread Starter
Le Mans Master
Joined: May 2003
Posts: 8,877
Likes: 3,556
From: Fernandina Beach FL
2023 Restomod of the Year finalist
2020 C3 of the Year Winner - Modified
a1sensei-
"Such improperly introduced fuel could easily distribute itself unevenly between the cylinders."
It's a dual plane intake-and I would guess the plug farthest away from the carb (1-2 &7-8) would be seeing LESS fuel. And there is no evidence of gas running down the carb-sight glasses are half full ( or half empty if you're a type A personality)
When I got back from the trip-I just pulled number one-Which doesn't look that bad now-SO the crudded up plugs could have happened from day one.
The car is still seeing GREAT gas mileage-over 17 a few weeks ago.
"Such improperly introduced fuel could easily distribute itself unevenly between the cylinders."
It's a dual plane intake-and I would guess the plug farthest away from the carb (1-2 &7-8) would be seeing LESS fuel. And there is no evidence of gas running down the carb-sight glasses are half full ( or half empty if you're a type A personality)
When I got back from the trip-I just pulled number one-Which doesn't look that bad now-SO the crudded up plugs could have happened from day one.
The car is still seeing GREAT gas mileage-over 17 a few weeks ago.
Racer
Joined: Aug 2002
Posts: 289
Likes: 0
From: Albuquerque NM
even more thought about that gasket....it could be drawing oil from the intake valley and would better explain the areas of oil deposits (2,5 &7) one thing is it's still a easy fix....if the gasket was the issue you still could get good gas milage...;-)
Racer
Joined: Mar 2005
Posts: 473
Likes: 2
From: Champlin Minnesota
I don't mean to highjack his thread, but take a look at these plugs. All my plugs look this way, and I am not sure that this is how they should look. Previous owner put a gm crate 350 (330hp) in the car and put a Edelbrock 1406 600 cfm carb on it, unsure if he ever tuned the car properly.
Race Director
Joined: Nov 2002
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From: Taylor Michigan
Originally Posted by a1sensei
Well maybe I'm missing something here, but from what I read, you drove the car 2k miles with no mixture problems, replaced the fuel pump and are now running rich and fouling plugs. Is it just me or is everyone ignoring the obvious. If your fuel pump is putting out too much pressure, it could unseat the carb inlet valve, overfill the float bowl and cause the carb to vomit fuel. Such improperly introduced fuel could easily distribute itself unevenly between the cylinders. You may need a fuel pressure regulator valve. Just my 2 cents worth. God bless, Sensei
The plugs appear to be fuel fouled. Your stock pump will only produce about 5-6 LBs of pressure. The engine is too rich. The electric pump will normally produce much more pressure on the needle and seat than a mechanical pump. Your best bet may be to install a pressure regulator or better yet, go back to the mechanical pump. A common mistake with the use of an electric pump. If this is correct, you may have fuel in the oil. too.
Safety Car
Joined: Oct 2004
Posts: 3,725
Likes: 5
From: Minnesota
Originally Posted by davidm_comp
Previous owner put a gm crate 350 (330hp) in the car and put a Edelbrock 1406 600 cfm carb on it, unsure if he ever tuned the car properly.
