How to read plugs?
Thread Starter
Instructor
Joined: Oct 2011
Posts: 123
Likes: 0
From: Ovid NY
How to read plugs?
I changed out my plugs a while back, before upgrading to a walbro 255 fuel pump and going to Br7ef plugs for a 150wet shot. The plug show is a one of the TR6s I pulled I had been running on them for a while with the stock fuel pump, stock injectors 28.xx on my 02 C5 and spraying 100 wet shot just a few times for some fun runs. My question is does this mean I had been running rich or lean and how do you tell? keep in mind I had the plugs in for about 6 months before changing.
I am going to a ported fast 78 here next week and I wanted to keep the stock injectors the car made just over 400whp on my current cam, stock 241 heads/full bolt on setup. by looking at the plugs does it look like I am running lean at all already on the stock injectors? I do have the upgraded fuel pump now so I would think that is some added security.
I am going to a ported fast 78 here next week and I wanted to keep the stock injectors the car made just over 400whp on my current cam, stock 241 heads/full bolt on setup. by looking at the plugs does it look like I am running lean at all already on the stock injectors? I do have the upgraded fuel pump now so I would think that is some added security.
Le Mans Master
Joined: Jun 2008
Posts: 5,284
Likes: 235
From: Rockledge FL
black is rich, white to grey is lean. tan is ok.
http://www.mudinmyblood.net/forum/vi...pg=sprkplgchrt
http://www.mudinmyblood.net/forum/vi...pg=sprkplgchrt
Thread Starter
Instructor
Joined: Oct 2011
Posts: 123
Likes: 0
From: Ovid NY
Thanks for the chart there, Mine seems to be about normal and it def richend up some at least at idle with the colder plugs (Br7ef) Im running now. I knew the tune was conservative as I was told by him as well as many others who have used the same guy to tune there cars, I could deff make a little more power most likely but I like it safe
Team Owner
Joined: May 2005
Posts: 23,682
Likes: 9
From: Flagstaff Az.
Thanks for the chart there, Mine seems to be about normal and it def richend up some at least at idle with the colder plugs (Br7ef) Im running now. I knew the tune was conservative as I was told by him as well as many others who have used the same guy to tune there cars, I could deff make a little more power most likely but I like it safe
Le Mans Master
Joined: Sep 2009
Posts: 6,937
Likes: 348
From: My interests are mobile
^correct.
Also, at wot, combustion pressures will reveal mixture quality at the bottom of the porcelain, not the top. The top of the plug indicates idle mixture and low bmep ranges. As stated, you should ideally use new plugs, do a wot pull with juice then immediately shut off. From there inspect the base of the porcelain with a magnifying glass and flashlight or use a plug inspection tool that's cuts the threads away. Plug reading is a lost skill that few understand how to do properly.
Also, at wot, combustion pressures will reveal mixture quality at the bottom of the porcelain, not the top. The top of the plug indicates idle mixture and low bmep ranges. As stated, you should ideally use new plugs, do a wot pull with juice then immediately shut off. From there inspect the base of the porcelain with a magnifying glass and flashlight or use a plug inspection tool that's cuts the threads away. Plug reading is a lost skill that few understand how to do properly.
