Triumph Repair: 1975 TR5 conks out after it heats up, fuel pressure gauge, compression stroke

Question
QUESTION: Hi, My TR6 1975 conks out after it heats up.  It runs beautifully when I first start it, and then after about 5 minutes its starts to conk out.  I replaced the rotar, which broke when I was checking to see if that might be the problem, but that didn't do anything.  Any ideas

ANSWER: Hi Ashok,
You say it is a TR-5 and a TR-6. Which is it? TR-5 is fuel injected and a TR-6 is carbureted.
Just having a car "conk out" narrows the possible faults to about one thousand. You will have to do some testing to narrow it down a little more.
All engines only require three basic items to run. Compression, fire and fuel with conditions on each.

1. compression-- You need to run a compression test to be sure the engine itself is OK and can run. You need to see 125 to 180 PSI on all cylinders and only a small amount of difference between cylinders.

2. Fire --- The spark should be a thick blue spark and be at the correct time. A rough quick test is to pull a spark plug and connect the plug to it's plug wire and lay it on a metal part of the engine. Put your thumb over the plug hole and have someone spin the starter while you watch the plug spark. When the cylinder is on the compression stroke it will push your thumb off of the plug hole and make a "Pop" noise and the spark plug will make a "Click" sound. If the two are in order like "Pop-Click" or "Click-Pop" then the timing is probably so far off that it will not start. When the timing is close enough to start, it will seem that the "Pop" sound is causing the spark "Click". This is an old mechanic's quick test when an engine does not start. If it seems to be off a little, you need to use a timing light and set it correctly.

3. Fuel --- You need a combustible fuel available to each combustion chamber. First you need a fuel supply to the carburetors (or injection system) To test this you need a fuel pressure gauge connected to a "T" in the fuel line close to the carbs (or injection system)

Let me know what you find and we will go to the next step to narrow the problem closer.
Howard

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

QUESTION: Thanks for your speedy reply. It's a TR6 (TR% was a typo).  Unfortunately, I don't have the tools for most of your suggestions.  Are there any simpler steps I could take before I take it to my mechanic.  As I said, in the morning the car runs fine for about 5-10 minutes until it heats up -- so that seems to indicate that the problem is heat related and that the (engine and fuel are fine).  I also, by the way, replaced the gas filter.

Answer
You will spend much more money throwing money at the problem than the few tools necessary to do the tests. You can probably even find the tools at Wall Mart, they are not expensive tools and the same tests are appropriate for any car.
Your symptoms do not put the problem in a small area. If you had brought me the car in a shop, I would have to run the same tests. I learned a long time ago to run tests to find a problem. I even learned to block out of my mind what I thought it might be so as not to lead me down a wrong road. Many mechanics fix cars by throwing parts at it until it is fixed. If you have deep pockets just keep putting parts on until you fix it. Or test the car and only replace the bad part.
Howard