Hi Roger, I installed a Weber DGV, and the fuel pressure is a little over
2.5 lbs.
I ordered the weber after the CD150 went nuts after a rebuild. In
retrospect, the rebuild was fine, it was the new fuel pump I installed
shoving 5+ psi down it's throat that caused the problems.
----Original Message Follows----
From: Roger Elliott <elliottr@rmi.net>
To: Paul Meyer <paulfmeyer@msn.com>, spitfires@autox.team.net
Subject: Re: [Spits] 79 Spitfire with SU carbs
Date: Fri, 29 Jun 2007 18:25:34 -0500
I have been chasing similar problems for quite a while. It never occurred
to me that the problem could be too high of fuel pressure.
What did you need to set the pressure at to make the car run correctly? I
stopped at Napa, they had one that could be adjusted 2 - 4 pounds and one
that could be adjusted 4-9 pounds.
Thanks,
Roger Elliott
Paul Meyer wrote:
>Several years ago I swapped carbs on my '78.
>Similar fuel problems resulted, which were eventually identified as being
>caused by the new carb requiring less fuel pressure. Idle was ok, but as
>soon as I increased rpm or fiddled with the choke, it would roughen or
>stall. I too replaced the fuel pump, but that only made things worse.
>
>
>I put in a cheap, in-line fuel pressure regulator, and got some
>improvement, but the cheap regulator caused flow problems in high rev
>conditions.
>
>Ultimately, I put in a higher quality fuel pressure regulator, and that
>solved it.
>
>
>
>Paul F. Meyer
>
>Home Phone: 781-551-8574
>Cell Phone: 781-801-3170
>e-mail: paulfmeyer@msn.com
>
>
>
>
>----Original Message Follows----
>From: David Woerpel <dwoerpel@wi.net>
>To: spitfires@autox.team.net
>Subject: [Spits] 79 Spitfire with SU carbs
>Date: Tue, 26 Jun 2007 17:43:27 -0500
>
>Hello,
>
>I am helping a friend with a 1979 Spitfire 1500. He's removed the
>Zenith and installed 2 S.U. HS4's. I'm one of the masochistic types
>that likes working on SU's and have no problem with the H4's on my MGA
>or H1's on the Bugeye Sprite but this problem has us stumped.
>
>The car has been desmogged, the head lightly shaved (I don't know how
>much) and the rest is stock as far as we know. It was running happily
>and he decided that he wanted SU's. The carbs are set correctly. We
>started with the jet adjusting nut at 12 flats down (yes, they are
>centered). The float levels are at 3/16", oil in the dashpot (1/2"
>above tube). The car starts and runs on choke and the pistons rise
>equally but when the choke is gradually reduced after, 3-5 min., it
>starts to stall. Add choke; it runs. Push off the choke and it wants
>to die. When we tried hand manipulating the throttle it occasionally
>coughs back through the carbs and dies.
>
>The owner had ordered a new mechanical fuel pump which we installed. It
>ran better off choke momentarily but then fuel poured out both float
>bowl overflows. I know the mechanical pump isn't putting out too much
>pressure so I'm suspecting the float needle and seat. New rubber tipped
>ones are on order. The coughing back through the carbs makes me suspect
>timing but when it runs it's pretty smooth. Just for kicks, what are
>the timing specs for a 79 1500? He has no manual and mine are for my
>above cars.
>
>Any suggestions would be very helpful. Thanks in advance.
>
>Dave
>59 :{)
>59 MGA 1500
>05 MCS
>Burlington WI
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