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: [EMAIL PROTECTED] > > > > > ----Original Message Follows---- > From: David Woerpel <[EMAIL PROTECTED]> > To: [email protected] > 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 > _______________________________________________ > Spitfires mailing list > [email protected] > http://autox.team.net/mailman/listinfo/spitfires > > _________________________________________________________________ > PC Magazines 2007 editors choice for best Web mailaward-winning Windows > Live Hotmail. > http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migration_HM_mini_pcmag_0507 > _______________________________________________ > Spitfires mailing list > [email protected] > http://autox.team.net/mailman/listinfo/spitfires _______________________________________________ Spitfires mailing list [email protected] http://autox.team.net/mailman/listinfo/spitfires
