Reply to "Initial jetting recommendations - O-3310S Holley 750"

Guys, thanks for the input on the carb. I pulled the 750 off the white
Pantera and temporarily installed the 735 that I used to run on the red
Pantera. While the 750 was off, I converted it to a 4150, installed the
plain spring and have set the accelerator pump and float levels.
Unfortunately, I've not had a chance to run it yet as it's been raining
and raining and raining some more. I had a problem with 735 Holley
metering block gaskets. Holley has different gaskets depending upon
whether or not the metering block is equipped with an accelerator pump
transfer tube:

http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars...ock_gaskets.jpg.html

The metering block on the left has an accelerator pump tranfer tube above
the power valve and uses a gasket with a semi-circular notch above the
power valve cut out hole while the one on the right has a small hole instead
of the transfer tube and uses the gasket without the notch. I pulled the
brown gasket out of my 735 Holley even though it does not have an accelerator
pump tranfer tube. I replaced it with a blue non-stick gasket of the same
style before I realized it was the wrong gasket. I've since replaced it with
the proper style. It is currently jetted with the stock 66 primary and 78
secondary jets and has the stock plain spring but a short (4.5") power valve.
The latter was on the recommendation of someone I know who has had a fair bit
of experience tuning the 735's.

> Remember that if you are using the holley automatic choke thermostat that is
> a "universal" thermostat and will generally open too quickly.

It's weird but that was never a problem on the red Pantera with that carb
but the white Pantera has a larger capacity radiator (and a milder engine)
and takes longer to warm up. In fact, the white Pantera has manual fans
and I generally never have to to turn them on, even in stop and go traffic.
In any event, it does seem like the choke is coming off early.

> I would change the squirters to a 25 and the spring to the plain silver one.

I've changed the springs but am holding off on the squirters until I run
it with the wide band for a while.

> I have found that the choke thermostat off of the 84 Mustang GT works very
> well. It is easy to get also as an aftermarket part.

Good tip, thanks. I've got a 4180 that supposedly came off an '84 or '85
Mustang 5.0L. I'll take a look at it's choke set-up.

> And don't forget the fuel level settings. Too low and the carb leans out
> and too high and it floods. Don't take them for granted. Remember the
> carb angle in the Pantera can be different and thus effect the correct
> fuel level setting.

Floats are set so that with the engine running, it just starts to dribble
out the sight holes when the car is rocked gently.

> 18 sound sligh for vacumn and usually the power valve is half the vacumn
> .. was it at the carb ..if so its 1/2

It was manifold vaccum. For a manual transmission vehicle, Holley suggests
a power valve opening point half the idle vacuum. Others suggest 2" below
the lowest reading you get at part throttle cruise vacuum. I'm going to
start with 4.5" which is lower than either of those methods would suggest.
Most Holleys have PVCR's that are just too large so delaying the power valve
opening might not be a bad idea (better would be to properly size the PVCR's).
I'm curious as to what effect it will have when I put the wide band on.
We'll see how lean it gets before the power valve opens. When I ran the
735 Holley on the red Pantera, it was really hard to get the vacuum to
drop much unless I went to WOT so I ran a power valve 2" below my cruise
vacuum but that car had a fairly different 351C (2+ points more compression,
more cam, single plane intake) than the one in the white Pantera. When
the rain stops, I need to drive the white Pantera around with the vacuum
gauge hooked up to see how it behaves, double check the ignition (still
points) and then hook up the wide band.

> I would make sure the play in the accelaertor pump lever jiggles about .015,

Currently, I've got the accelerator pump set at WOT with 0.020" clearance
when the accelerator pump is bottomed out though Holley recommends 0.015".
Some books say to simply take out all the slack in the accelerator pump
linkage when the throttle is closed but that yields much larger than 0.015"
clearance at WOT. That would delay pump action.

> I would use std 28cc accelerator pumps NOT 50cc should work.

Agreed, the 50cc pump is way too big for this engine.

Dan Jones