[DeTomaso] Mechanical Fuel Pumps

[Will Kooiman]

Regarding the Robb McQuarrie fuel pump...

I have pn 1021 - the one for up to 1100HP.  Pn 1020 is for up to 550HP.
They are very similar.  I think they use the same parts, but they're
finished to different levels.  For example pn 1021 has an adjustment at the
top where you can set the outlet pressure.

The main body is a heavy casting - not like the lightweight junk you'll get
from Autozone/Kragens/etc.

The diaphragm body rotates to any position.

The fuel inlet is on the side.

The fuel outlet is on the bottom.

He has a regulator that includes a port to return some fuel to the tank.
The small amount returned to the tank is to prevent vapor lock.

You can boost reference the regulator.

You can use the vapor return port to run to a fuel pressure gauge.

You can run the regulator in dead-head or bypass mode.  Dead-head is
recommended for this fuel pump.  Bypass is recommended for an electric pump.

The spring on the pump arm is stronger than the normal spring.  In other
words, it's hard to install because it's larger AND because there's a lot
more force to overcome from the pump arm.  I almost forgot - it's also
harder because the larger size makes it hard to get the bottom bolt in
place.

Here's how I do it:  I put a long stud in the top hole.  I use a bolt in the
bottom.  Rotate the engine until it's at TDC on #1, but 180 degrees out.
This is the position where the eccentric is pointed straight up.  Start the
fuel pump on the stud, and push - hard.  As it compresses the arm, it will
slide onto the stud.  The stud will hold the pump in place, so you can
install the bottom bolt.  Don't forget the gasket.  Make sure the pump arm
is on the eccentric before pushing.

I've also thought about doing this...  Compress the pump arm on the work
bench, and then put a plug on the fuel pump outlet (or inlet?).  The vacuum
might hold the arm down so you can simply slide the pump into place.  I
haven't tried this.

Do you need one?  I don't know.  It's overkill for a street car - just the
right amount of overkill for a Pantera.  I don't think there's a better
mechanical race pump available.  Of course, I could be wrong.  I'm not an
expert on fuel pumps.

I can't tell you how it well it works.  My car is still dead.  Maybe it will
be back on the road in July.

Send Robb an e-mail.  He'll answer any questions you have.

-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of JDeRyke at aol.com
Sent: Sunday, June 28, 2009 11:49 PM
To: cengles at cox.net
Cc: detomaso at realbig.com
Subject: Re: [DeTomaso] Mechanical Fuel Pumps

In a message dated 6/28/09 7:20:53 PM, cengles at cox.net writes:

> Jack DeRyke wrote an article about this very topic.  The exact location 
> of the article escapes me, but I bet Jack will chime in and enlighten us.
> 
Yes- many times due to the possibility of crash damage ripping the tank 
bottom like a Kleenex box. The steel is so thin, you can actually punch a 
screwdriver clear thru a good tank with little effort. I suggest running a 
top-mount out-line from the fuel filler or the rollover valve openings
rather than 
rigging a Christmas tree of fittings hanging off the bottom. If you 
absolutely must, use a minimum-clearance banjo fitting and a large loop of
armored 
flex hose (suitably routed) between the tank & pump, for a strain relief. 
I'm completing an article for next month's newsletter on adapting an 
in-tank fuel pump (exiting out the top) to a stock Pantera fuel tank. This
is not 
a 'teaser'; I had some unplanned problems with this adaption to our '72, but

its now done except for on-street testing. This should eliminate fuel 
boiling and vapor-lock, and with a bit more work, provide a larger fuel-out
line 
for high horsepower engines. As most know, the stock Pantera fuel-out line- 
either early or late tank- restricts fuel flow enough to limit horsepower to

around 450 real horses, give-or-take a few. Increasing the ID of the 
out-line to at least 3/8" cures this restriction for our street machines.
Real 
race cars use 1/2" ID fuel lines from tank pickup all the way to the carb 
inlets.   Cheers-- J Deryke


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