This is a problem most TR vintage racers run into when an engine like this
is run at full throttle for an extended period of time. The less expensive
fuel pumps will simply not supply enough fuel to an engine like this on
full song. When you have a pump like this, and have an in-cockpit fuel
pressure gauge, or if you are brave enough or stupid enough (that's me) to
stand and watch a fuel pressure gauge while a car with a hi performance
engine is run up on a chassis dyno, you can see the pressure drop off at
higher rpms, sometimes down to near zero.
One fix is simply to get a Holley fuel pump and regulator. The pump by
itself puts out too much pressure so you do need a regulator to get it down
to a pressure that our carburetors like.
Unfortunately, that is not an ideal fix either, because the Holley
regulators may (or may not) fail after a period of time and get erratic. No
one seems to know why because there's nothing to the innards of these
things, just a ball, diaphragm, and spring. The ultimate solution is to get
a $100 bypass regulator and run a return line to the tank, all of which
seems like real overkill, but it fixes the problem once and for all.
At 07:40 PM 5/17/2004, Walt Hollowell wrote:
>I could use a little help from some FOT members that drive TR6s with triple
>Webers.
>In hard street use and SCCA autocross events I have no problems. However,
>this past weekend I was club roadracing
>on our Albuquerque, New Mexico 14 corner 1.65 mile road course. After the
>4th or 5th lap on full throttle the engine started falling flat as if I
>dropped a couple of cyclinders due to lack of fuel (110 octane racing gas).
>I had to fall back in the pack and not push too hard (not difficult with my
>driving skills) or things would just run flat. I suspect I do not have the
>volume of fuel I need for this racing application.
>My engine is putting 155 hp to the ground (just did a chassis dyno last
>week) with a few more ponies to be found with some more tuning. We are
>racing at 5,500 ft. above sea level. I have 10.5:1 compression, ported
>heads, stiffer valve springs, 286 cam, headers and triple Weber 40 DCOE
>carbs. My main jets are 200 air and 115 fuel. Emulsion tubes are F7. Idle
>jets are 55, acelerator jets are 40 and the bleed off is set at zero. I am
>using the cheap electric fuel pump you can get at Pep Boys which has
>performed OK up till now..If it is the higher volume of the two types they
>sell. A fuel pressure gauge shows I am getting between 2.5 and 3 PSI of fuel
>to the carbs. I am not using the stock mechanical TR6 fuel pump at all.If my
>problem is in fact not enough volume things now get difficult. Do you think
>I can just hook up a second (same type) fuel pump in line to increase the
>volume a little or am I going to have to find a high volume, low pressure
>fuel pump with a return line back to the gas tank.
>Has anyone else came across a similar problem?
>Any suggestions?
>
>Thank You
>Walt Hollowell
>Albuquerque, New Mexico
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