Hello All!
The other night I started up my 72 MGB/GT with the choke as
usual. Only this time, I forgot to unchoke after a few minutes.
I was cruising down the freeway and thinking to myself, WOW,
what POWER, what SPEED! What's up with THAT? My car was zipping!
(Seemed a little quieter on top of that.)
So, after I pull into town, I look down and AHH, left the choke on.
Turned the choke off, picked up my wife, and back onto the freeway.
Now, just the normal moderate power/speed. Also, under normal
operating conditions, while cruising at around 60, my car tends to
surge. (Power, lack of power, Power, lack of power at about 4 times
per second. More noticable down hill, less noticable up hill, or under
acceleration.)
Hmmm.. So I've been thinking over the past couple of days about what
might be happening, and how I might be able to gain that power without
leaving the choke on...
Here's what I've been thinking, and I would appreciate any insight as
to what is REALLY going on...
1. Choke Out = Richer Fuel/Air mixture.
2. Around town, seems to have plenty of pep, choke or not.
3. Around town, typically < 3K RPM.
4. On the freeway, typically > 3K RPM.
5. Notice that under heavy acceleration, power seems to drop above 3K.
6. Therefore: Need richer mixture > 3K RPM.
I believe that I have my carbs correctly adjusted for the fasted lean
idle. I have a fairly free flow tuned exhaust system, Dual SU Carbs,
some type of hot (PO) cam, Crane Electronic Ignition, Vaccume advance working
correctly, static timing about 20 BTDC.
Questions:
a. Should I richen up the mixture a bit?
b. Are my needles wrong?
c. Is it OK to run with the choke on?
d. What's the best way to get the performance increase I noticed while running
with the choke on?
Thanks in advance! :)
David Hall
dhall@vcd.hp.com
72 MGB/GT.
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