DIY_EFI Digest V5 #57

[Walter Sherwin]

Shane;

The #85 injector that I mentioned below is in fact the same thing as what is
oft referred to as the "#80" injector.  In either case this is the injector
which comes standard from Holley in the 900 CFM 4bbl TBI, injector P/N
250R-51A, service P/N 522-26.

The #85 actually flows about 85 pounds per hour of fuel @ 15psig (Holley's
rated pressure).  It will slip into your smaller TBI injector housing pod.
When four of these injectors are housed and fed via the pod passages, and
driven via four 4/1 amp P&H drivers, you can usually get about 310 pounds
per hour of maximum fuel flow.

I would aim to calibrate your setup at a pressure somewhere between
12-15psig.  Any less pressure, and the injector spray quality is really
"globbery".  15-18psig will get you more volume, which in your case you
don't need.  Over 18psig, and you risk hydraulic shut down of the injectors.

I don't know if you intend to purchase new or used injectors, but here's a
tip that will save a lot of headaches when either buying used,  or
performing regular maintenance at a later date.  Measure the resistance of
each of the four injectors, from the very tip of one terminal post to the
very tip of the other terminal post.  The spec is 1.3 ohms +/1 0.1 ohms.
Now measure the resistance of the same injector, from the cylindrical collar
that appears to sheath the terminal post to the other collar around the
other terminal post.  The resistance should be identical to what you just
measured above.  If not, there is an electrical resistance and/or break
between the collar and the terminal post somewhere.  If you look at the
mating connector, you will see that the connector terminals engage over the
outsides of the collars, and that current must flow through the collars in
order to enter the terminal posts and windings of the solenoid.  I've been
caught by this a couple of times myself.  Sometimes a dab of solder at the
collar/post interface will fix this problem.  Sometimes not.


Walt.



Date: Tue, 8 Feb 2000 17:35:02 -0600
From: "Shane Buss" <shaneb at ev1.net>
Subject: Re: Holley TBI Injectors VS Pressure

about about the 80# injectors? i'm about to get some of those


- -----Original Message-----
>Shane;
>
>The Holley B2 TBI injectors do not typically like a lot of static fuel
>pressure.  I have never tested the #65's myself, but I have extensively
>tested the #85's on my flow bench.  According to what I've read & heard,
>both are constrained by the same limitations.  The basic problem is
>associated with the fact that the internal ball and pintle rod are
>magnetically "coupled", and that the internal hydraulic differential forces
>(a product of increased fuel pressure) can become sufficient to separate
the
>two elements and cease flow entirely.
>
>With a 4/1 amp driver, the #85's are happy puppies at 15psig when hot.
>Roughly 18psig is the upper hot operating limit, with same.  Cold, on the
>bench, the #85s will operate irregularly above 20'ish psig and will
>completely shut-off at 26psig.


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