[Fot] Fuel issue

[Barr, Scott]

What is your fuel pump and regulator combination?  I had similar problems with my similarly-spec'd 1300 engine.  Jack Drews worked out a theory with regard to mismatches of fuel pump and regulator.  If you wanted the specifics, you could dig back through the archives to find the discussions of it.  But the upshot of it was that if you have a pump that is putting out pressure at a level too close to the post-regulator pressure you're shooting for, it can cause trouble.  At his recommendation, I switched to a Holley Blue pump with the standard Holley regulator.  It worked for me.

Scott (B.)

-----Original Message-----
From: Fot <fot-bounces at autox.team.net> On Behalf Of Andrew Devenish via Fot
Sent: Friday, August 9, 2024 1:10 PM
To: Tony Garmey <vintageclassicsus at outlook.com>
Cc: FOT Triumph <fot at autox.team.net>
Subject: [Fot] Fuel issue

Guys, 
          My car ( 1300, 12.5:1 comp on Sunoco 110 race gas, dual HS4 ) is still giving me grief. I’ve chased all the things I can think of, but still same problem. It starts and runs great, but after a few laps of the yard ( 5-6, only 1000ft  or so per up/down lap, so quick accels then braking to turn ) it goes very lean ( I have O2 sensor ) and stops. I’m running it without the hood for these test runs. It always stops at the entry to a turn. 
         I’ve been working on it a lot, so know it has fuel pressure, and the float bowls are full of fuel. All plugs look very similar. The needles (AAA) are the spring type, and the slides move freely. I use ATF as fluid, but have tried 50 weight too.
        After a minute or so it will fire back up, but only run enough to get back to the shop before going lean again. If I pull out the choke it will run, but is unstable. 
       I have wrapped headers and a heat shield around the carbs but they do still get hot.

       Any ideas ?  Thinking to try some less volatile fuel as it seems heat related and the Sunoco evaporates so fast !
     

Thank you, 
      Andrew Devenish

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