These came from a two barrel Motorcraft carb I got
off a Ford V8 F150 pickup truck in the junkyard.
Anybody have any idea how much power this truck had.
I think it was built in the mid 70's.
The two needle valves will be used to adjust the dual
main jets and the needle and seat will be used to regulate the
supply. I am amazed how tiny they are. The F150 could not
have had much power.
I may add two more needles for idle adjustment.
I don't think I will need them however as the engine will idle
at 2000 RPM.
This is a common carb used on many Ford products I think
Now all I have to do is find some taps with the right threads
for these needles.
Almost done. I'll get an estimate of the cost of machining the body
from Larry. There are only two major parts. The body and the diaphragm
cover. If this works on the RX8 p-port slide throttle dyno engine we will
be home free.
Paul Lamar ...No rotor no motor.
Paul,
Brought the holley to work today (forgot it yesterday).
Will ship ups ground today, so you will have it this week.
I can get all the odd size taps used in carbs.
Larry
Thanks Larry. Hopefully the jets are larger than the Motorcraft carb jets:)
--
Paul Lamar ...No rotor no motor.
You looking for the physical size, or the orifice size? The best way to get a
high calibration orifice is the "pills" from kinsler fuel injection. They
require a retaining devise as they are not threaded, but worth you looking
at.
Larry
Orifice size and max needle diameter. Max needle diameter on the
Motorcraft parts is 1/8th inch (.125) which I guess should be good enough for
a main jet for a 120 HP one rotor. I have two adjustable mains. One for each rotor.
Each rotor can then be individually manually tuned using the EGT feedback for each rotor.
Max needle size on the float needle is .140 but of course the orifice or seat
is less than that. My guess is around .070 to .1 inch. No drill set
here to measure it exactly. I suspect this is marginal for a 250 HP
rotary. I could be wrong. According to this chart it is fine. 100 pounds of fuel
per hour or more. It just looks small to me :)
I am going to check on the price of the Motorcraft 2 barrel carb overhaul
kit. Should be cheap. Of course you will be throwing 95% of the kit away:)
I am amazed at the simplicity of this type of carb. I have no doubt it I can get it to
work fine for the p-port slide throttle rotary when manually leaned. The pancake air
cylinder on the throttle knob will work double duty as an engine primer and an
accelerator pump.
Paul Lamar ...No rotor no motor.
Hi Paul,
What is the source of the 2 PSI chart ( I'd like to pursue other
pressures) and what is its significance? If you are regulating fuel flow
with the orifice/needle combo does the PSI matter since you could simply
screw the needle in more? Or does this come into play at WOT when the
PSI/orifice combo solely determines flow. If this is the case would
PWM'ing the pump be a feasible leaning method? ( i.e. 5 PSI at takeoff
reduced to 2 PSI at altitude). I'm not understanding if the needles
are varying the flow, or if they're fixed and the pump pressure is
varying the flow, or some combination of both. Thanx, Dave M
I think that came from Kinsler web site. I could be wrong. At the time
I was looking at a lot of web sites. It is a handy chart.
Well a float level or a diaphragm carb keeps a constant pressure
on the main jets so this chart should be valid. In most cases you change
the main jets to adjust the mixture through out the range
except perhaps at idle and so called power mode. Power mode
is changing the mixture from stoichiometric (14.7:1) to 12.5:1 for
max power. Another circuit in car carbs we don't need.
I am using adjustable mains so I can set it anywhere.
Now in your case the PWM pump will do both. It will increase the
pressure across the mains and at the same time increase the flow.
I hope you are using a mass airflow sensor to set the pump pulse
width. Please keep us informed on your project.
A PWM pump is a neat way to go but it is electronic and some people
have a thing about electronic. Electronic is easier than it looks but
mechanical is harder than it looks IMHO :)
--------------------------------------------
This is the part number for the overhaul $18 kit. No main needles
but I did get the float needle and seat. The rest of it is useless.
Still cheaper than making them.
BWD Engine Management Technology Part #10035D Carburetor kit.
I got it in Pep Boys. The guys at Pep boys say this kit is used
in most Ford 2 barrel carbs for a period of 15 to 20 years.
Some were large V8's. That is probably well over a million
engines and carbs.
BWD Automotive 37-18 Northern Blvd.
Long Island City NY 11101
We might have to make the adjustable main needles out of 10-32 socket head screws
or some such.
No big deal for on NC lathe. I can probably afford to run off a thousand.
Paul Lamar ...No rotor no motor.
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