About Scott Cypher Expertise Can answer about Triumph Spitfire 1500, GT6, TR6 Engine repair, modifications, mechanical questions, part interchangeability,
Can't answer Triumph other models not mentioned above, cosmetic, electrical or interior/exterior trim issues.
Experience Triumph enthusiast for 22 years; own a TR6, TR7, Spitfire, GT6. Race a Spitfire in SCCA, Preparing at GT6 for Vintage Race, TR7/TR6 for street use.
Organizations FOT, NASS mail list, SCCA
Education/Credentials None specific to the subject matter.
Question on my recently acquired 72 tr6...both carbs have just been rebuilt (a second time) by a pro...I installed them on car..motor still wont run unless choke is pulled virtually all the way out, which is what it was doing before he rebuilt them..fuel pressure at carb is 2-1/2 lbs...vacuum reading is 17...timing is 10 btdc with vac line plugged...tried 4 atdc and everything in between..sync'd carbs with unisyn...new metering needles have tried adjusting them even down to where they are now, turned all the way in to right,clockwise..air valves operate correctly, but if i try to raise 1/8 inch it will slow / stall...have reset idle screws, linkages, choke cables, fast idle...put new carb to manifold gaskets on...cleaned fuel pump and nothing seems to affect it. with the choke pulled it runs great...but try to push it in even a quarter inch and it dies...all things point to lean, but i cant get any change by messing with any of the above. I think the manifold to head gasket should be ok as I haven't messed with it and the vacuum is at 17..the pro was adamant that he set the floats accurately as he knows their sensitivity.
HELP !!
Answer The only thing I can think of is to check all the ports on the carbs and make sure they are capped; there are alot of emissions related hoses, and if you have one unplugged and its sucking air, it could cause this condition.
the choke "trick" points definately to fuel/carb issue, so I would stop with non-carb/fuel related tweeks like timing and focus on fuel pressure, fuel float, etc.
Will putting your hand over the opening on the carb have an effect (with no choke)? It should serve a similar purpose if its getting to much air. Right now you are adding fuel to compensate for too much air; so either not enough fuel is getting in (pump/float/needle/idle mixture), or too much air is getting in (unplugged port, vacuum leak)
Vacuum at 17 seems to be low, I think. Try spraying starter fluid around the intake manifold & related gaskets/ports, and see if the engine speed rises. If it does, then you have a vacuum leak.
