Can someone explain how to read the spark plugs for rich or lean? Do you read the base or the tip? I took my plugs out tonight to check them and the base circle (next to the threads) is black and tip is a greyish (by tip I mean the curved metal where the spark hits). I compared these to my old plugs (before I was turbo) and they look nearly identical.

I have a HRC turbo kit installed (about 500 miles on it now) and was checking the plugs this evening. Based on the grey color, I may be running a bit lean and may turn up the idle pressure to increase WOT pressure but would like some suggestions from fellow 2gnters.

I have the Vortech SFMU (2.72 disk, hard spring) with idle at 50 psi running Stage II boost at 6/7 psi max with stock injectors. When I tested the car with the fuel pressure guage installed under WOT, I saw about 100 psi (+/- 5 psi).

I've also noticed some inconsistencies on my A/F Guage (blinky light Autometer Lunar Series). It seems when I stomp on the pedal for WOT the led goes to the lean condition but if I gradually increase to WOT (gradually accelerating not just immediately standing on it) then the LED light stays right in the center of rich. I'm assuming maybe some slow response from the ECU??? I don't get it.

I've been told to watch exhaust temps rather than the gauge as they are more important. Here are some numbers to toss around. If I boost the car in second gear to 5,000 rpms, the gauge reads around 1300 degrees. If I shift and continued to boost in third gear till 5,000 rpm, it will go up to 1400 degrees. At that point, I usually stop boosting and let the motor cool down.

The car is running great. I hear no knock (which I am assuming I would hear if it was lean), no misfires, nothing. It pulls extremely hard. I am probably being paranoid but just wanted some opinions....any input would greatly be appreciated.

Thanks in advance,
Kurt

Check your HRC manual, I believe Stage 2 fuel pressures has to be around 120 or so. Haven't looked at mine for a while, so correct me if I'm wrong guys.

u read the electrode housing or white part of the plug an optimum would be light brown or card board brown or maybe slightly darker to be safe
grey/white or no color means SUPER lean, unless running avgas or methonal it wont have any carbon=)

The HRC manual says that for 9 lbs of boost you should see 105-110 lbs of fuel pressure. I figured 7 lbs of boost should be around 100.

I think to be safe I am going to change the calibration disk in the SFMU to the 7:1 disk.


Here's some calculations:

7:1 disk (3.62 disk)
(Rise rate * lbs of boost) + Idle Pressure
(7*7) + 50 psi ~ 100 lbs of fuel pressure (perfect)

5:1 disk (2.72 disk)
(7 * 7) + 50 psi ~ 85 lbs of fuel pressure (slightly lean)


I also have the hard spring installed so I may have to bleed off some extra fuel but this should get my a/f guage to constantly stay in the green.