My First Intake
and Carb Upgrade (continued)
the car at Willis Automotive, we were ready to make our dyno
runs. Keep in mind, on this day we didn't dyno the car in true "stock"
form, with the original factory intake and two-barrel carburetor.
We know from past experience the factory 2V 289's put out
an anemic 150-155 horsepower to the wheels and are lucky
to crack 200 ft-lbs. We were more interested in comparing
between the two combos identified on the previous page.
Round 1 - Edelbrock Performer Combo
The first run of the day would be with the Edelbrock Performer
intake and matching EPS 600cfm carburetor. Other than setting
the idle speed, no prior tuning was performed. After making
a couple of pulls to adjust the timing and get consistent
results we found the motor liked 40 degrees total advance,
in by 3500 rpm. Our best Edelbrock dyno run yielded a peak
176 horsepower and 224 ft-lbs of torque (refer to red plots
on dyno graph below). The air-fuel ratio was impressively
rock-steady at an ideal 13:1. Little did we know at the time,
these would be our numbers to beat.
Round 2 -Weiand - Holley Combos
As the engine cooled we pulled the Edelbrock combo and bolted
on our Weiand/Holley combo. As mentioned above, we had our
choice of either the 570 of 670 cfm Street Avenger. There
are some at Holley who calculate 570cfm as the right choice
for a stock 289, while others (including Jim Dralle) are adamant
the 670cfm is more appropriate. We tested both, first the
Like the Edelbrock EPS, the 570cfm Street Avenger is a vacuum
secondary and electric choke carburetor. This combo also fired
right up without fuss.
We got our Holley 570cfm Street-Avenger
carburetor and Weiand Action-Plus manifold assembled beforehand
to cut-down on swap time at the dyno.
We made the swap in under an hour as the motor cooled
after our Edelbrock dyno runs. Notice we left the distributor
in place to avoid having to reset the timing.
the idle speed and made an initial pull with this combination.
The results were 172 horsepower and 218 ft-lbs of torque.
We noticed the air-fuel ratios were dipping into the low 11's.
In attempts to lean it out we changed the vacuum secondary
spring to the lightest one included with the carburetor. Since
the carb comes with pretty small primary jets (54's) we left
them alone. On the second pull, air-fuel ratios were improved
to high 12's, but still not near the 13:1 we'd like to see
for this engine. While peak power matched the Edelbrock combo
at 179 horsepower (4600rpm), focusing on the peak would be
very misleading. Power was down across the board in the lower
rpms, by as much as 12 horsepower. Torque was also down about
6 to 10 ft-lbs across the board, for a peak of 221 ft-lbs
Well aware that the 570cfm Street Avenger may be undersized,
we performed another test with a 670cfm carburetor - also
a vacuum secondary Street Avenger.
We also tested a 670cfm Holley
Street Avenger. Our stock 289, however, didn't respond
to the increased air flow capability.
The upside to Holley carburetors is the infinite tuneability. However,
for the novice this can be the downside too. A jet kit,
vacuum spring set, and pump/needle tuning kit are wise
investments with any Holley carbuertor purchase.
We changed the vacuum secondary spring to the lightest
one possible in order to ensure the secondaries would open fast and completely. This didn't do much for our overall power
The 670cfm comes with 65 jets in the primary and secondary
Again, we had to perform some tuning
to get the air-fuel ratios out of the rich range. First up
was the lightest vacuum secondary spring. We followed this
by changing the primary jetting from 65's as delivered, to
60's. On our final pull we were still seeing air-fuel ratios
in the low 12's at wide-open, but this was a marked improvement
on the high 10's we saw out of the box.
The 670cfm proved to be a much better match for our 289. We'd clearly recommend no less than a 650cfm carb for
any stock 289/302. The 670cfm made the most peak horsepower
at [email protected] In fact, the 670 seemed to be coming alive
in this rpm range, but our stock cam and valve springs weren't
going any further. However, as with the 570cfm carb, the excess
fuel killed the average numbers. We made an effort at tuning
the 670 for about four pulls, but simply ran out of dyno time.
Before we get into the conclusions, it is important to
remember that the combinations would perform differently on
an engine with more modifications - particularly where there
is a greater demand for air-flow via a larger camshaft, ported
heads, or more cubic inches.
With that said, when it comes to a bolt-on, no fuss carburetor,
we have to hand it to Edelbrock. The have nailed it with the
#1406 Performer series carburetor. On a stock engine like
our 289, the 600cfm Edelbrock performed flawlessly. Other
then setting the idle speed, we didn't need to perform any
other tuning. The air-fuel ratios were dead-on at 13.1 throughout
the rpm range. The Edelbrock combo yields very consistent
results, great torque and horsepower across the board.
On the Holley side, we must say we weren't surprised. The
570 and 670cfm Holley Street Avengers are great carburetors, but
they need to be tuned. Holley tends to jet them in anticipation
of a modified motor, and this means they are on the rich side.
On a simple motor like this one, you get penalized with losses
in power until you tune the carburetor properly. The question
is, whether that is a reasonable demand to place on a new
enthusiast looking to take their first step into engine
mods. We think it may be asking too much - even the average
enthusiast will not spend the money and time to tune on the
dyno like we did. We know Holley's will make more peak power,
you can see them pulling away at the end of the curves, but
we'd like to see Holley really develop a carb that performs
across the power curve, straight out of the box.
With the manifold selection, we are happy to say that there are
now two equally good candidates out there for small block
Fords running up to 5500 rpm. In fact, we decided to throw
together a little "wildcard" combo, where we tested
the Edelbrock carburetor atop the Action Plus manifold. Our
seat of the pants impression of this hybrid combo was "holy
smokes, this is the strongest this car has ever felt".
The dyno results confirmed this, showing slight gains
everywhere with the Action Plus over the Performer manifold.
Round 3 - Wildcard Combo! Edelbrock Carburetor & Weiand
The Action Plus' runner flow balance claims may prove to give
the manifold a slight edge. To isolate the effects of each
manifold we dynoed the Edelbrock 1406 carburetor atop the
Action Plus manifold. This combo made a peak of 171 horsepower
compared to 166 for the Edelbrock/Edelbrock combo, and average
power was up a handful across the rpm range with the Action
Plus intake. Torque was also up by 6 ft-lbs at peak. We'll
have to schedule a round two in the near future to see how
the Action Plus would do on a little more aggressive engine.
The Bottom Line
Want a no-fuss, minimal tuning,
idle to 5500rpm combo that makes excellent power? This
Perhaps for some this article will make
the decision easy, but we suspect for most it will only fan
the flames of the Edelbrock versus Holley debate. Our advice
is to ask yourself if you want a no-fuss, bolt on and go combination
that will run flawless for years to come. If so, the red lines
in the charts above are all you need. Or do you anticipate
making more modifications to your engine, and thereby prefer
a combination that can grow with you. Do you like tuning,
and searching for maximum power from every combination? If
so, get a Holley and a tuning kit and never look back. Or,
if you don't want to think about it that much, split the difference
and go for the Wildcard combo.
We're planning more intake and carb tests, so tell us below
what combinations you'd like to see tested.