Problem: "She's got two idle speeds boys" -"tto slow 6 hunnert, and
Seven-TEEN hunnert and only SHE decides WHEN ...and she changes her mind
pretty reg'lar like. -Jus' like a woman
Equipment:
Induction: 3 old 1960s RottenChester 2GC two barrel carbies ( built up from
seven junkyard refugees ) on a 3 deuce Offenhauser manifold. Set up with
home built aluminum progressive linkage with spherical rod ends and double
return springs jus' like ya''saposdta. End Carburetors have idle circuits
and power valves plugged and deleted, 56 jets(?),Accelerator pumps intact
and working. Center carb has manual choke, 58 jets (?) and all other
functions working. All floats set according to spec, with proper gauge -all
"re-built" and set up over a long winter by your resident genius, the
writer.
Block: '66 small journal 327 Chevalay block poked to 4.060 (332 c.i.)
( annybody can have a 350... -"it takes a real man to have a 327" )
Pistons: KB 1966 Hi-Po 327 pop-up type with .12 dome.
Rods: polished n' peened 327 Steel, ARP bolts
Compression ratio: 10 1/4
Crank: .010 /.010 327 polished & detailed throws, Balanced assembly.
Cam: Rumpity, Comp Cams Hydraulic, 490 lift intake & exhaust, w/"losta"
duration and lotsa lope. Nirvana after 2800 RPM to 8000. :-)
Vacuum; 7 inches @ slow idle, 17 inches @ highway speed.
Ignition: Circa 1969-70 style Delco single point Dizzy with Mallory points
and condenser triggering a MSD 6A spark box and Blaster coil mounted inside
car and under the cowl with coil wire sneakin' it's way thru a grommet in
the firewall. Looks good, runs good, starts good.
Driving characteristics: Absolutely Loves WOT but usin' that on the street
alla time can get you lodging down at the Graybar Motel perty quick like.
Response at mid range speeds good, -excellent throttle response. Off idle
response often comes with a "poof" a hesitation but driveable. She don't
like me to make'er come back to life when she's restin' I'm thinkin'. "The
Combination" is very susceptible to climatic changes; on sunny breezy days
she runs like a... well you get the idie. But on days less than ideal,
-with a touch of "weather" in the air, you're out there adjustin' the idle
speed because she's changed ...AGAIN.
Results of extensive B.Y.* R & D:
Using a slim flashlight, Gas is discovered DRIPPING in an intermittent,
"occasional" pattern from the left annular discharge nozzle inside the
center, primary carburetor venturi at idle speed with engine "warmed up".
When it does, of course the idle speed goes UP then RPM tapers off as gas
is used up until the next drip that is... While this phenomenon repeats
itself over and over, the vacuum rises and falls on the Stewart-Warner gauge
in the dash from 7,( up to maybe 15 inches ?) WHEN this happens you can
stand yards away from the car and it sounds like there's someone inside
playin' upsy-downsy with the gas pedal kinda spooky like.
We stressed WHEN because sometimes this phenomena doesn't happen.
Seemingly, it's tied to colder, damper weather patterns. We realize that
with a Rumpity cam with a Looooong duration, one often does turn up the idle
air speed screw to attain a decent idle speed. Does this perhaps, have a
detrimental affect on the whole enchilada ? As an "aid" to easy
adjustments, I've soldered a small brass tubing nut onto my idle screw to
eliminate the need for a screwdriver. We've been operating ( and coping )
with this setup for 6 years, and 22,000 smiles of drivin'...
*BackYard
" If we knew what we were doing, they wouldn't call it Research "
-A. Einstein
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