Lack of common sense won't help your Karma
Well folks,
On a beautiful "almost spring" day, I arrived at my dyno appointment 5 minutes late (My Flight Commander had a last minute task handed-out). However, as luck would have it, Chris, the dyno guy, had to rescue a buddy of his who had blown his F150 Lightning way out in the west-side of Albuquerque. So he didn't show-up until about 4:30 p.m....but at least he showed-up. Chris is a real cool guy, so he began setting everything up for the L81's run.
We got the Vette up there, and the plan was for after the first pull, I would be adjusting the initial timing to about 12 -14 degrees. However, the first pull sucked. It is the one in red. Notice the red fuel mixture line how it goes up and down until it gets real close to the 10 to 1 air/fuel mixture (best is about 13.0 to 1).
View attachment 12920
Before the second pull, I adjusted the initial timing to 14 degrees. I also turned the idle mixture screws in about 1 turn (the wide-band sensor was showing 12 to 1 at idle). Since I had to remove the air cleaner, I placed a cap on the carburetor tube for the
Thermac hose and removed the air cleaner assembly all the way. So I "checked" everything, and I told Chris to go for the second pull. The second pull is the blue one. Notice how the fuel mixture improved to about 12 to 1.
With me dragging my deflated spirits like remnants from a shredded balloons, I headed to my Vette and loaded my tool box in it. I got myself in the Vette, and I started the engine.....wait a minute...now what????....why is the "check-engine-light" on???? I suppressed my frustration, for I now was hoping to make it home 25 miles away...looking...looking...Hey! what tha heck??!!
I found the four wire connector from the distributor disconnected....I must've forgotten to reconnect it after adjusting the timing...now, I felt like I should be changing my name to "Dumb A$$"....so that means that my second pull was not correct....so there's hope...
hnoes
Driving home, I kept thinking why was the fuel mixture so close to 12 to 1??? The computer was not controlling much at that time...perhaps the fuel mixture only...and it was not scheduling timing advance. So what could it be? running rich...running rich...hummm...I wonder if I am having a problem with the Thermac?
I got home, and I decided do a simple test. I checked everything to make sure that it is hooked-up correctly...it was. So I disconnected the flexible cold air ducts, and at the same time, I rev-up the engine and see if the snorkel doors are doing anything....left front snorkel is wide open during the entire revving-up and down. I do the same on the right hand one, and it is closed at idle, at part throttle, and at about 4k rpm...hummm....that should cause a rich condition, so the good news is that I found what is causing the L81 run rich.
Did I mentioned that the bad news is that today's Dyno run sucked!
