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Chapter
8
12/2/2000:
The car has been stored about 65 miles from my workshop since June, and
this AM I had the chance to bundle up and drive it (sans heater) through
the 17 degree morning back home. IT loved the cold air and went happily
along at 70mph as long as I kept the choke at a very precise 50% opening. I
take this to mean that the turbo, which reads about 2 pounds at cruising
and 5 pounds on acceleration is providing the right balance of air for the
over-rich mixture provided by the choked carb. Actually, the transition
from idle to high speed is pretty good. The car doesn't seem to smoke as
much, and maybe the rings are getting bedded in a bit. Hope the richness
isn't washing the oil off the cylinder walls too much... Anyhow, I suspect
that the above situation indicates that if I were to provide just the right
mixture of gas and air to the carb (both coordinated in greater volumes) I
would get more power......so......on goes the 4-barrel.
The AFB
got its float bowl holes to the outside epoxied shut and now has air passages
drilled in to the bore of the throttle shafts to create "air
seals" to prevent air/fuel mixture from coming out. I carved air passages
into the plywood adapter plate(and gasket) and
led these to a tube which could be connected above the air horn. Didn't
fill the floats with foam yet. I sorta want to see them collapse! Maybe the
floats from the modern Edelbrock AFB will fit?.... Jon Myers, who races
'Spooky', a Lark with twin superchargers says that maybe some floats from a
Shakebutsu will fit. Some have pressure tested the AFB floats to 21# when
they then became unuseable. For more info on AFB carb prep go here to the McCulloch supercharger
site.
Found a
great piece at the hardware store called a "canning funnel" which
will bring the diameter of the turbo plumbing from 2" to 4"
smoothly. It looks strong enough to stand my projected max of 15# boost and
fits well over the AFB. Also at the hardware store, I found a little
anodized aluminum whistle which I will place on the end of the filler neck
of the radiator-cap blow-off valve. It will be obnoxious, but should give
me an idea about what is happening out there when I change caps. I need to
route the blow-off from the crankcase. On a conventional motor, this would
be thru a pcv valve into the air cleaner or valve cover, but I'm wondering
what this might do when it travels thru the turbo.....
12/9/00: Took her out for a spin, and
I do mean spin! She's leaking oil from somewhere near the front of
the pan on the driver's side, and maybe the problem isn't crankcase blow-by
after all. Did get some suggestions from the Blowthru list on dumping
off the pressure. Seems that late 60's or early 70's Mopar products
had a system of dumping pressure with some scavenging from the exhaust
system. I'll check this out. Anyhow, again it was a rather cold
day, and the choked one barrel carb allowed good idle and
acceleration. The boost started coming on to 5# at what I would
predict was about 4000 rpm (no tach yet) and then, rather suddenly it would
soar to 10# at which point the engine would falter at the same time that
the car began to turn sideways (rear end sliding to the left). If you
noticed the big meats on the car, and then add sudden torque and an icy
road (remember, this is Minnesota.....) you'll get the idea. I guess
this says that I'm on the verge of some real engine performance. I think
the whistle I put on the outlet of the radiator cap (pop-off valve) limited
air flow and effectively changed the rating of the cap. I promptly drove
back to the garage to take it apart and begin the process of adding the AFB
and eliminate leaks in the induction system (there were some very high
pitched sounds sending dogs running in all directions....) and in the oil
pan (or something nearby). This will give me an opportunity to go 12v
and check out the grabby front brakes (oh yeah, that ALSO made my last trip
a bit exciting....). I'll also be working a bit on the boost control
circuits 'ala Gus' (see links for Gus
).Exploded
pieces of boost control soldering on elbow complete control and .025
inch orifice
12/17/00: Took off the carb this
weekend and noted that the linkage arm on the internal "toilet
seat" waste gate was bumping against the lower side of my intake
manifold. It was close, but I'll bet that the gap in the gate passage
was big enough to account for the somewhat slower 'spool-up' than I had
expected. In reality, this has probably been a good way to
break in the engine, but now, the only way to remedy the situation was to
remove and modify the intake manifold..... 1 2 3 Not my
favorite task given the difficulty getting at the two center bolts (inboard
of the closely coupled turbo). Anyhow, it was also probably time to
redesign the manifold to take the AFB in a way more conducive with good
flow, and allow me to engineer in the wastegate canister. Until now,
the gate has been controlled by a choke cable to the dash, because the
canister was in the way of the manifolding in the stock position. I
will mount it further rearward on a bracket welded on to the tail end of
the intake manifold.
This required modification/extension of the actuator rod. I will use
the threaded adjustable canister from a slightly later turbo for this and
spin up an extender (out of a
big nail!) which threads on and fits the little peg on the wastegate valve linkage.
The AFB will now sit lower
on the engine than a stock carb if I can get all the throttle linkage out
of the way 1 2 3 4 5 6 . There will
still be room for a plate to add H2O/Alcohol injection. I'll hunt
around for a Nitrous plate to use for that, or maybe even take the throttle
body injector that came with the turbo and inject with THAT. I
will avoid the need for computer control by actuating the injector with a
relay set up as a buzzer which is turned on and off by a home-made
adjustable 'hobbs switch'. I'll use that to control anything that
needs to come on when the engine starts to make demands at higher boost
pressures. Since I have an extra gate canister, I'll mount this on a
little bracket with the rod attached to a set of points from some
distributor. To change the switch's 'on' pressure, I simply adjust
the rod and points. Once built, it can be mounted anywhere and if I
calibrate it at different point-gaps, I'll be able to make fine
adjustments! Depending on boost , A/F ratio and detonation, I will turn on
auxiliary electric fuel pumps, solenoids for H2O injection, and voltage
booster to the fuel pump. Also planned during this down-time is the
addition of an A/F meter, the tach and the fuel pressure
gauge(outside). I'll try to group these in one small area of vision
that a video tape recorder can be focused on....
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