Re: [ihc] Adjust-a-jet?

[bearbvd@xxxxxxxxxxxxxx (Greg Hermann)]

At 12:27 PM 12/1/04, Ryan Moore wrote:
>Anyone know anything about the adjust-a-jet from holley for the 2300?
>
>Something that replaces the metering block and lets you add a mixture
>control so you don't have to change jets as you change altitude... curious
>if it'd work for our applications.
>
>-Ryan

Used one more than once. Not only on a 2300, but also on both ends of a 4150.

Couple of things:

The PVCR (power valve control restriction orifices) in the adjust-a-jet
metering block are HUGE. Grotesquely so. Enough so that a 2300
(PARTICULARLY one with smallish venturis, such as IH used) goes utterly PIG
rich as soon as the power valve opens. You need to epoxy these two holes
closed and then drill appropriate sized (about 50% of the main jet
diameter) ones beside them for the thing to function at all decently.

Also, the jet size in the 'variable' portion of the unit is rather on the
large size--enough so that it would take the thing over a range of about
twenty jet sizes in going through its adjustment range. For this one, I
soldered it shut and re-drilled it smaller--sizing the diameter so that the
area of that one was equivalent to the INCREASE in jet area one would get
by increasing the main jet size from the very smallest one one might want
to use, at say 11K feet MSL, up eight or ten jet sizes. Be sure to pay
attention to ACTUAL jet size vs. nominal size in doing these calcs--they
are NOT the same with Holley shite !

Apparently, Holley wanted to let guys THINK they were playing with their
jetting on the fly, but avoid getting blamed for boxes full of holed
pistons----

The thing works pretty decently once it's properly sorted out. I finally
got mine to where it kept things right with one click change for about each
thousand feet of elevation change.

NOT recommended for 'aircraft' type applications, though !!! :-)

Greg
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