QuestionHi;
I have 1080 TRIUMPH TR7 Conv. with dual STROMBERG CD175 Carburetors.
Carburetors were rebuild long a go ! but newer ran good , since.
Now car runs on two cylinders ! is this a usually a problem with carburetors ? cozz I heard that one Carb. run 2 cy. and other Carb. run the other 2 cy.Is it ? that one Carb. work with Cy.# 1 & #4 looking at the engine front to back , and the other Carb. work with ; 2nd & 3rd. cy.
This is NOT the firing order ! that I refer to , it is the position of cy. by looking the engine.
Front to back , cy.; 1, 2, 3, 4,.
Cy. 2 & 3 are firing ! and 1,& 4,. are NOT.
Can you please ! try to help . ?
Tony
AnswerHi Tony,
Any time I would receive cars with running problems I need to run tests and I worked out a procedure that needed to be followed. There are only three things needed for an engine to run and they are Compression, Fire and Fuel with conditions on each. The tests must be done in the correct order too.
Symptoms can give you a lead but For the most part using symptoms to diagnose is a waste of time and can often lead you down a wrong road. Testing is 100% sure method to diagnose a problem providing you do it in the correct sequence.
Compression First and always first. A compression gauge is not expensive and will be useful on any gasoline engine. Pull all the plugs and spin the engine over at least 5 revolutions with the throttle wide open. You should see from 125 to 170 PSI on all cylinders with little difference between cylinders.
Fire (Ignition) is always second. We had a scope at the dealerships I worked in which made the ignition test a matter of seconds but it can be done at home with very few tools.
Pull #1 spark plug and attach the plug wire back on the plug and lay it on a metal part of the engine where you can watch it. Put your thumb over the plug hole and have someone spin the starter while you watch the spark plug.
When the piston comes up on compression it will blow your thumb off of the plug hole with a "Pop" sound and the spark plug will spark with a thick blue spark (thick as a pencil lead) (not in bright sun light). The spark will make a "Click" sound. It will seem as though the "Pop" is causing the ""Click". If however, you get a "Pop-Click" or a "Click-Pop" the timing is probably off and may not start. If the spark it thin as a hair and colored yellow or orange it is a weak and that too may cause it not to start.
Fuel is always last. This is easy to test with a spray can of starting fluid. If an engine fails to start and will on starting fluid, you have a fuel problem for sure. If an engine runs poorly and will not rev up but will when starting fluid is sprayed into the intake, you for sure have a fuel problem.
There is also a shortcut on "Fire and Fuel" tests by spraying starting fluid into a intake of an engine that will not start. If it starts it is fuel problem and if it don't start it is a Fire problem.
In your case with #1 and 4 not firing you will find that you have either a compression problem or a ignition problem. So run the tests as I outlined and let me know what the test results were and I will give you the sequence of tests to follow the results.
The carburetors feed #1 and #2 for the front carb and #3 and #4 for the rear carb.
Let me know,
Howard
