Triumph Repair: TR6 Idles Very Rough, rear axles, valve adjustment

Question
QUESTION: Howard, I'm restoring a 72 TR6 and thanks to your help I've got the brake system, clutch and rear axles all operating properly.

I'm moving to the engine next and it will not stay running without the choke pulled partially out(even after being fully warmed up). I tried the test where you slowly cover the air intake on the carb and the engine speeds up when I do this and then eventually stalls.  I noticed in one of your earlier notes that this likely means the carbs are set too lean. I checked the spark plugs and they are all black and carboned up. Thoughts...

As this car hasn't been driven in 10 years, I thought I should start with the electrical side of things by changing all spark plugs, the rotor, condenser, points,  distributor cap and do a wet and dry test on the cylinders. Depending on the results from the compression checks, the valves may need to be adjusted.

I wonder if I should do all of the latter before tackling the carbs but I'm not sure where to start first.

Any help would be appreciated.

Kim



ANSWER: Right, You can't do the carbs until the engine is correct, valve adjustment, compression test, clean plugs and timing set to specs.
After that is done you go to the carbs because the set up of the carbs is based on reactions of the engine and if the engine is not set up correctly you will get false response when trying to do the carbs.
Let me know when the engine is finished and I will walk you through the carbs.
Howard

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

QUESTION: Howard,

I reset the valve gap at .010 on all of the valves and then proceeded to check the compression(the gas pedal was full depressed during these tests).  Here are the results:

Cylinder  1   2   3   4   5   6

Dry       5   145 125 150 150 145

Wet       15  145 125 155 150 150

I double checked the valve settings on #1 and checked the compression again with the same results. I installed new spark plugs and the engine ran for about 30 minutes prior to setting the valves,etc. The spark plug for #1 was pretty much clean while #3 was carboned. The other spark plugs showed a light brown color on the tips.  Can I check anything else before digger deeper into the engine to determine the issue with #1.

I'd like to avoid rebuilding the entire engine as a number of the cylinders are still good at 145-150.  How can I check to see if it's the head or the piston or ???  Is it possible to replace the piston while the engine is still in the car?  The odometer reads 44,000 miles and I believe this is accurate given the condition of the car.   

Thanks for your help.

Kim

Answer
The true method to test what is wrong with #1 is to get a fitting from one of the mechanics tool trucks or a auto parts store that caters mainly to mechanics and repair shops. The fitting adapts an air hose to the spark plug hole. You set #1 on TDC and the car in 4th gear with the hand brake on hard or have someone hold the foot brake hard while you connect the air hose to the fitting. This pressurizes the combustion chamber with 100+ PSI of air. You then open the throttle and listen in the intake for a hissing noise. Then go to the tail pipe and listen close at the tail pipe. This checks for any valve leakage. Good valves make no noise at all. To test for a hole in the top of the piston or broken rings just open the oil filler cap on the valve cover and listen. There will be hissing there even on a new engine. You will need to listen to the hiss of one of the good cylinders to be able to recognize what is a normal ring hiss, but if you have broken rings or a burned hole in the piston it will be very evident. This same test is good for a blown head gasket too by just removing the coolant cap while pressure is applied to the plug hole. It will also be very evident as it will blow coolant all over.
This test requires the fitting and compressed air but it is a 100% positive test of everything in the combustion chamber.
Howard