Triumph Repair: TR7 Stalls When Hot, intake vacuum leaks, blown head gasket

Question
I recently had a blown head gasket repaired at a local mechanic that has experience with British cars including the TR7.  When he completed the repair and restarted it he said it was hard to crank and needed a new choke.  He replaced the choke with one from another carburetor he had.  The engine starts very easy but has a real high idle until it reaches normal engine temperature.  It initially returns to a normal idle when warm but then the idle begins to fluctuate and then stalls.  It always restarts easy and runs great but as soon as you put the clutch in the engine immediately dies. I would appreciate any information you may have. It is a 1980 TR7..thanks

Answer
Hi Danny,

The problem does not sound serious but if you have not had the car out of the shop very long you should return it to that mechanic for a readjustment of the tuning. It needs to be returned to him for a re-torque of the head anyway in a few hundred miles of driving. The re-torque of the head must be done stone cold so you may need to leave it all day or over night.

If I were that mechanic and you returned it to me for this problem I would check the ignition timing and test for any vacuum leaks in the intake and then adjust the carburetors a little to correct the idle problem when heated up. The fast idle cold is normal and should be that way.
The cold fast idle should be about 1500 RPM and after it worms up it should drop to about 750 to 850 RPM as a normal idle. Also, be sure the top carburetor pots have engine oil in them.

The fact that it stalls at times hot and when the load of the clutch disengaged is an indication the idle is either set too low or is lean in mixture. That is providing the ignition timing is correct and there are no intake vacuum leaks.

Howard