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Tuning
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Stay tuned,
this ought to be a fun area of the site, I'll post the tunes,
dyno runs and any thing else of interest.
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24
Oct 06 1st Dyno Session ever for the car! |
| The best run
and the worst run are on this chart. We had a few good runs,
then the AF ratio started going way rich at around 5600
RPM. Don't know what to make of that. |
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Carb was leaned
4% by changing the rods..
Timing 12 degrees initial
plus 24 mechanical, stock Pertronics curve.
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| Here Art, the
owner of Track Masters connects the wideband. The person
to the right is Lee, owner of C&L Performance, he was up
before us, testing some Mustang EFI goodies. Before
we started Lee estimated that car would make around 415
hp at the crank, he was right! |
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| We did
7 pulls total, but stopped when we ran out of time
at about the same time the AF ratio started going
rich. |
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12 Nov 06 Carb Stuff |
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We narrowed the problem with the rich condition to one of
several things, the carburetor probably, but another candidate
was that the engine heat soaked and the oil thinned out
at high RPMs causing the valves to not fully open. To try
to remedy this, I changed from 5W-30 Mobile 1 to 10W-30
Castrol Syntec and added a quart of STP Oil Stabilizer. |
| I added an extra
clamp to the hard line to reduce the vibration transmitted
to the carb. I also added a 3/4" 4 hole spacer under
the carb to see if it made an difference in the idle and
throttle response. The spacer was 1", but I had to mill
it down so the hood would clear the air cleaner. |
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| I have a rebuilt
Holley 4160 (3310-6) 750 CFM that I was going to try on
the car. It was converted to the 4150 style by the addition
of the secondary metering block.
I was a little disappointed
with the HP and torque, they seem low to me. So instead
of floundering around with more carburetors and jets, I
decided to order a custom
Bigs worked
over Holley and open up the exhaust a bit by removing one
of the Car Chemistry Inserts.
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| The
Holley's are a pain to tune and can make a mess
if you are not careful. To change the jets, the
fuel line and the float bowls must be removed
-- unless you buy a quick change jet kit. |
Tip: buy a flexible
stainless steel braided hose fuel line kit to connect
the bowls. That way you won't have to remove the
lines to change jets. |
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10 Dec 06 Bigs Carb |
| The new
Bigs Stage 5 750
CFM, wow! We opted for no powder coating; I left the
finish the chromate coating, its more "old school" or period
correct. (not that anything else on the car is period correct) |
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The Summit aluminum
carburetor spacer provides another large port for
vacuum. It was 1" thick. I milled it down to 5/8"
so the air cleaner would clear the hood. Note I've
since replaced the spacer with a
nitrous plate and moved the vacuum line to the
side of the manifold. |
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| The Bigs and
Holley carburetors compared, they are both 750 CFM,
but the Bigs has been worked over and tuned to the engine.
The most noticeable modification is that the choke is gone
and the bores are smooth. It looks like a Proform body,
I suspect it is. |
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| The stock Ford
throttle cable needed the spring removed to make it work,
it did not have enough travel. The air water trap
in the background is plumbed into the PCV, it captures any
oil or water vapor sucked from the engine. |
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Tha carburetor was installed and the car started. Too cold
to take the car for a ride, but it started up and did something
it never did before -- it idled fine cold with no choke.
With the Edelbrock Performer I had to choke it to get it
to idle when cold. The exhaust note changed quite a bit
too -- it sounds meaner -- right now its running much richer
than it was with the Performer. At this point,
we did not do any adjustments, not even the idle. Can't
wait for better weather! |
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15 Dec 06 Dyno with
New Carb |
| Made it to the
dyno today, AF ratio is much better and stable. The engine
made 20 more HP and 20 more ft/lbs torque with the Bigs
carburetor - a great improvement! Zero tuning except for
the idle and idle mixture - carb is right out of the box. |
Timing 12 degrees initial plus
24 mechanical, stock Pertronics curve. The idle AF ratio
was set to about 13.5 using the LM Wideband. All four screws
are about 5/8" turn out. The idle speed was set to around
900. After these adjustments, the throttle needed to be
feathered for a minute or so when cold to keep the engine
running.
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Overall the throttle response and drivability of the car
with the Bigs carb is just fantastic, it does not bog or
hesitate when you snap the throttle open. I must admit I
had my doubts at first. |
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