My air fuel gauge is temporarily out of order. I am trying to get my air fuel mixture proper. I have dual weber idf's. I have followed the basic instructions on redline weber's webpage and various other sources however I am not overly happy yet.

My car runs great and temperatures are good however possibly on the lower side which makes me wonder if i'm too rich.



I have a hard time finding a consensus on plug reading. I went out and drove my car to the edge for about 15 minutes then without letting the rpm's go below 3000, I checked the plugs. I have black soot on the threads and the entire porcelain is bone white however one plug 4 it is bone white until about 1/2 down- then it's black.

Any suggestions?

Sounds like you are a bit rich. That said...

If the car runs great, and temps are low then drive the heck out of it.
What are your head and oil temps?
Can you beg/borrow/steal a tail pipe sniffer to check your AFR?
Reading plugs is very hard with modern fuels.

Zach

Head temp cyl 1- average 290- max 300
Head temp cyl 3- average 300- max 310

Oil temp- normal around 180-210.


I am trying to figure out what is wrong with my air fuel gauge. Hopefully I will have that situated soon.

In order to read the plugs you need to run the car hard and shut it off a speed. If you let the motor come back down to idel speed you will get a false reading. You can check at defferent RPM that way, say like 3,500 RPM and shut it off. And check for that RPM. To see what it is doing at 3,500. You can check it at the top end or idle, but you can't check top speed if you let it idle. And they should never be completly white. That is too hot. You should be reading the porcelain down inside the plug. It should be tan. NGK had a thread on it on thier website.

I have been using an infrared temperature gun on the exhaust (egt) to set the mixture.

I worry about pulling out plugs when it's warm, for fear of mucking up the threads in the head.

2 reasons why a cylinder will run cool I found - it is either too lean (or sometimes but rarely too rich), or else it is not doing its share of work. Usually lean it up and it will get hotter. Sometimes you have to use the air correction screws to even out the 2 banks on 1 side.

It works surprisingly well though when you are tuning 4 individual barrels.