Triumph Repair: TR6 hard to start warm, vaccume, cylinder compression

Question
QUESTION: Jim,
I have  1973 TR6 that is hard to start when warmed up.it starts right up cold.If I shut it off (temp 160) and start it right back up its ok if I shut it off and it sets for 5-10 min I have to crank it for 20-30 seconds and it will usualy start back up but sounds like it's flooded except I don't smell gas fumes.I've installed new plugs set at .025. checked the valve settings .010 and rebuilt the cargs CD-175's.there are no fuel or vaccume leaks, the vaccume advance is working and the chokes are ok.the car has an allison electronic ignition and the timing is set.the engine temp never goes above 180 and i've checked it with a mechanical guage also.the cylinder compression checks are good at 145 psi to 150 psi.the engine doesn't lack for power warm or cold and runs real good it's just hard to start when warm after it has set a few min.got any clues for me please.

ANSWER: Bob,

Do you need to use the choke when starting cold?   And have you tried to use the choke when having the problem starting warm?  Or not using it, if you have been?

One possibility is that the mixture is set a bit rich.  


Cheers,

Jim

---------- FOLLOW-UP ----------

QUESTION: Jim,
 If the weather is cold or I haven't started the car for a few days I must use a little choke.I have tried using the choke when it's warm and doesn't want to start, it makes it worse I feel. when I pulled the plugs they wern't carboned up and looked to be just about correct in color.could the fuel bypass valves on the carbs be a problem or do you think the fuel might be boiling off while it sets?if it was fuel boil off what can I do about it?
Thanks
Bob

Answer
Bob,

It could be the thermal compensators.   The Bentley manual has good troubleshooting information.

If you suspect it's fuel boiloff, then having a friend give the air filter opening a shot of starting ether will give a quick answer.  If the fuel is boiling off, then you can consider making and fitting a heatshield to the carb setup.


Cheers,

Jim