Spark plug fouling
Thread Starter
3rd Gear
Joined: Mar 2003
Posts: 3
Likes: 0
From: Perth West Australia
Spark plug fouling
Greetings from Perth, West Australia.
I have an ongoing problem with my 1969 390hp/427 continually fouling #1 and #5 plugs. I have tried a range of NGK/Bosch and AC Delco plugs with no luck. Is there any benefit from running iridium or splitfire plugs?
Engine is basically stock with exception of headers, RPM Airgap manifold, Demon 750 cfm carb and flamethrower coil/ignition kit. Hood is a L88.
Any advice would be greatly appreciated.
I have an ongoing problem with my 1969 390hp/427 continually fouling #1 and #5 plugs. I have tried a range of NGK/Bosch and AC Delco plugs with no luck. Is there any benefit from running iridium or splitfire plugs?
Engine is basically stock with exception of headers, RPM Airgap manifold, Demon 750 cfm carb and flamethrower coil/ignition kit. Hood is a L88.
Any advice would be greatly appreciated.
Racer
Joined: Dec 2005
Posts: 325
Likes: 0
From: Partlow VA
How many miles does the engine have? Sound like you may have a valve seal problem.
Post a picture of the fouled plugs, this will help in diagnosing the problem.
Post a picture of the fouled plugs, this will help in diagnosing the problem.
Last edited by Vettkeeper; Nov 17, 2006 at 10:32 PM.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Recently put the Air Gap on and now the plugs are fouling ?
If so misaligned intake gasket is my bet
If so misaligned intake gasket is my bet
Last edited by MotorHead; Nov 17, 2006 at 11:32 PM.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
Since your only problems are with 2 cylinders it may be valve seals as the likely culpert. If so, it would be wise to replace all of them. This proceedure can be accomplished from the top without removing the heads.
Thread Starter
3rd Gear
Joined: Mar 2003
Posts: 3
Likes: 0
From: Perth West Australia
Spark plug fouling
Thanks for the advice.
The engine was rebuilt a few years ago but probably does less than 500 miles per year. I had the problem before the Airgap so will go down the path of replacing the valve seals.
Thanks again.
The engine was rebuilt a few years ago but probably does less than 500 miles per year. I had the problem before the Airgap so will go down the path of replacing the valve seals.
Thanks again.
