Triumph Repair: 80 spit runs and short time and quits, fuel fire, fresh oil

Question
Hi,

I bought an '80 Spit two years ago that was previously used as a parts car. The previous owner told me that it sat unused for 8 years.
I replaced all of the parts that were missing. With the aid of a mechanic, we were able to get it running again.
Recently, I have noticed that it will run really great for a while until the motor gets warmed up. Sometimes I can drive it for 10 minutes and it with suddenly die on me. consequently, I have to wait a while before it will start up again. Unfortunately, the car has to be cranked several times before it will start again.

I have done the following:
1.) cleaned the fuel lines (curiously found no fuel filter)
2.) checked to see if the fuel pump is working.(replaced)
3.) changed the coil.
4.) changed the spark plugs, cap, and wires. (not the rotor)
5.) changed the solenoid.
6.) replaced the ignition switch
7.) partial rebuld on the carb.
8.) checked the compresion, wet  and dry.
9.) fresh oil change
10.) replaced the brakes
11.) replaced the slave cylinder.
12.) needs an alternator though

It's really strange. I have been able to drive it short periods of time. It shift fine, has plenty of power, but for some reason when the engine gets hot enough, it cuts out and stops. I read an article about the vaccum advance, and vapor lock possibly being a problem for some Spits. Honestly, I know very little about distrubuters. I am surprised that I have done what I have on this car.
In short, I have tried to follow the model of testing to see if the car has fuel, fire, and air. It only appears to have all three. I have noticed however that it doesn't have the CEI Amplifier. It ran without it on several occasions. I am kind of tired of pushing this little car around the block. I really think that it is supposed to be doing the work, not me!

Thanks for your time, and knowledge.

Answer
Hi Daniel,
I have had many cars brought to me with similar stories and you need to do what I have to do on such a car. You are correct that Compression, Fire and Fuel is what is needed to run an engine. When an engine quits, one or more of these three is missing. So you must monitor as much as you can "At the time of failure". That seems hard to do driving down the road but it is not hard to do.
It is less likely that compression is going away because usually when compression goes away it don't come back. So at first we can rule that out and say we must be loosing Fire or Fuel. All you need to run the proper tests are a timing light and a fuel pressure gauge with a "T" fitting and a little extra hose.

Connect the timing light to the coil wire (not a plug wire) and run the wires out from under the hood and tape the trigger down and place the light under a wiper arm so you can see the flash of the light while driving. (if it is a bright sunny day tape a piece of card board over the end of the light to shade it but still see the light from the drivers seat.) Now take the "T" fitting and put it in the fuel line at the carburetor so the carb and the long hose to the gauge all receive fuel pressure. (Be sure to use hose clamps at all connections) place the gauge under the other wiper so you can see it too.

Now drive the car until you have a failure and quickly look at the light and gauge while the engine is still coasting down to see if you have lost fuel pressure (should be 1.5 to 3 PSI)(no more, no less) or the flash of the light has flickered. (a coil will flash so fast it will almost look like a steady light but any small failure will show as a flicker)

These test will show that you have primary ignition and most of the secondary ignition and it will show that the carb is receiving fuel at the time of failure. These are tests of "End result" Replacing a part is not a test of end result. You need to know 100% if fuel is being supplied to the carb at the exact time of failure and is a spark being supplied to the distributor cap at the time of failure. The cap, rotor, wires and plugs do not normally give the symptom you have. A carburetor can but you need to know if it is being well supplied at the time of failure.

let me know of the results of the tests.
Howard