how to tell a plug has fouled?

I don't have a lot of experience fixing cars myself as you can probably tell from the title of the thread. Is there a simple way to tell if a spark plug has been fowled-or that all cylinders are not running? I have a carbed 78 gts that running a bit rough with some sputters and backfiring. Any help appreciated!

 

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Stephen

 

thanks that is a help

-do you just pull the extenders out by hand and check with a flashlight?

 

You have to remove the extender by hand, then remove the plug.
When replacing the plug be sure to use a torque wrench to prevent damage to the head.

What I am concerned about is that I learned this stuff on Fords and Chevys and the cost of the tool was about the same as one trip to the mechanic. The value of a torque wrench
was brought home when I stripped a spark plug hole on a 1947 Ford with alumin heads.

A Ferrari is not the place learn or practice on, unless you have piles of money.

Stephen

 

I never torque a plug, hand tighten only, when the socket stops spinning freely, maybe a quarter more turn to snug it - that's it. Besides risking stripping the threads during the install, I don't want to destroy the plug removing it 12 months later when I service the car again.

And even with a torque wrench, you need to be careful. I once had a torque wrench (a major brand wrench at that) not work and as a result, I kept tightening until the bolt broke. This was one of my old trucks when I was replacing a water pump and it cost me many hours of drilling to get that bolt out, then I had to widen the hole, then get the right size helicoil, etc. Killed hours, and my back. After that, I always test a torque wrench before I start using it.

Phil

 

If a plug has fouled, it will be oily.

If it is fowled, it usually has feathers stuck in the electrode.

 

I learned something new today. Thank you!

 

Damn, You beat me to it... LOLOL.....

 

In my experience a fouled plug(s) causes sluggish performance from your engine.If the plugs are black/sooty your mixture could be too rich also!
I would remove and replace all spark plugs if they havent been changed for some time.Checking that the electrode gap is as specified!
Geoff

 

14 1/2 foot pounds. I got the procedure:
http://ferrarichat.com/forum/showthread.php?t=107757&highlight=308+spark+plug+torque

There is a description of the method about half way down the page.

Stephen

 

The best way to tell if any plug is firing is to connect it to a timing light and let the engine idle. If the light consistently flashes it is firing. If you have problems with some of the plugs fouling you are probably running with plugs that are a bit too cold. I went from NGK BP7ES to NGK BP6ES plugs and it made a world of difference.

If you have a timing light, run each plug through it and see which are not firing.

 

Lately I have similar problems (stuttering, backfires) with my carbed 308. It usually happens after driving for fifteen minutes or so and especially after a long period of constant speed/revs (highway). The problem only lasts for a short time and after that it stays away. Sometimes downshifting/accelarating helps or just let it sit idling for a minute.

So could this be fouled plug(s) as well or don't they return clean by themselves? Technically I'm quite a noob so apologies if this doesn't make sense.

Best regards, Peter

 

The NGK catalog states that BP7ES with .6mm gap are the correct plug for a 308.My car is running with 8's and there is a definite flat spot.I will be changing to 7's when it gets here(still on the boat from UK).If that doesnt improve things I will go to 6's.Colour of plugs is tan to grey atm.

 

Scroll way down near the bottom of this incredibly long page and you will see two images, one with text and the other color pictures of Bosch fouled spark plugs.
Look for the title
Here are the charts on how to
read spark plugs.
They can tell you a lot.

http://www.specialtauto.com/delorean-parts/engine-tuneup.html

OR I’ll just simply attach the two images I mentioned above.
Image Unavailable, Please Login
Image Unavailable, Please Login