We've run up to (and sometimes over) 5 psi with stock needle
valves. Grose jets in place of stock needle valves don't work worth
a hoot. 2 to 3 psi should be fine. The bigger deal is the fuel pump
/ pressure regulator combination. If you have a fuel pump that puts
out, say, 5 psi and you use a pressure regulator to drop it to 2.5
psi, a common problem is that there's not enough pressure
differential to make the regulator work reliably. When it
malfunctions, it shuts down the fuel flow. We had several races were
we ended up taking out the regulator and running on the fuel pump
directly to get it to run right the entire length of the
straight. That's how I know that, at least in some cases, the SU's
will take 5+ psi without problem. You do want a high flow fuel pump
too, so you don't run the float bowls dry on long straights.
We run the Holley blue fuel pump and the pressure regulator that
comes with it. The best regulators feed fuel back to the tank so are
constant flow deals (as I understand it). We've not spent the $$$ to
experiment with that setup after coming up with the holley
stuff. You can see the holley kit at
http://www.pegasusautoracing.com/productdetails.asp?RecId=2516
. We've got the pump in the trunk and the regulator under the hood.
- Tony Drews
At 12:08 PM 7/31/2006, WEmery7451@aol.com wrote:
>Another elementary question: What fuel pressure is the list using for the
>original stock SU Carburetors for the TR-3/4 engine. I know that
>this has been
>discussed before.
>
>We recently mounted a fuel pressure gage under the hood between the regulator
>and carburetors. Someone who I had worked with at Duquesne Light in the 70's
>set my regulator, and I have been racing with this setting ever since. I
>plowed through both the red and the gray books and did not find any
>recommended
>fuel pressures. Then an old article surfaced recommending 1.5 lbs.
>pressure to
>SU carburetors.
>
>I am presently getting 2.2 lbs pressure to the carburetors. Maybe a little
>more pressure is required for racing.
>
>
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