Are you starving for fuel? It seems like if you are not getting enough fuel you would run until fuel bowls empty.
Have fuel & spark but it still shuts down
My 1600cc flat 4 with dual Solex carbs, dual port heads, headers and a centrifugal distributor shuts down after about 12 minutes of running. After about 15 minutes of not running it will start and run fine for about another 12 minutes. Could there be an icing problem inside the intake manifold with no exhaust warming jackets as stock?
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Not a fuel or spark problem.
If the float bowls are not staying full it may do that.
I will check out those carbs. Thanks.
A possibility I would look at first would be the metal fuel line entering the front shroud which might be too close to the #3 exhaust causing the fuel to boil in the gas line, starving the pump. Make sure the metal line and any other flexible lines do not get too hot or touch any part of the engine heads or case.
If the engine is starving for gas after 12 minutes idling, it should starve after a minute or so of driving, if it is a fuel delivery problem. If you can drive it for 12 minutes then it stops, it might be a vacuum forming in the fuel tank because the vent line is blocked. This would probably only happen if the fuel tank is fairly full and the gas cap is sealing correctly. In this case the fuel pump cannot overcome the vacuum in the tank. Remember the fuel pump only creates about 3psi of pressure to the carb so it is not very powerful. After 15 minutes, the vacuum is probably gone and so will allow the pump to draw fuel again.
There is also a minor chance the coil is overheating and shorting internally. Runs for a short time then shorts. Cools off and is able to start again. Condenser might do the same if really old but would a 1/2% chance of this happening. This is not the first place I would look but if you cannot seem to get the problem fixed after significant time spent on the fuel system, I would look here.
I have had several squarebacks in the late 70s and 80s. Really liked them. My wife had a 69 I built with a 1776cc engine, 286 degree cam, merged headers, centrifugal distributor and dual 40mm DCNF Webers. Performed really well over hills, even with four people, as the power really came on after 3K RPMs. Love those flat 4s.
If the engine is starving for gas after 12 minutes idling, it should starve after a minute or so of driving, if it is a fuel delivery problem. If you can drive it for 12 minutes then it stops, it might be a vacuum forming in the fuel tank because the vent line is blocked. This would probably only happen if the fuel tank is fairly full and the gas cap is sealing correctly. In this case the fuel pump cannot overcome the vacuum in the tank. Remember the fuel pump only creates about 3psi of pressure to the carb so it is not very powerful. After 15 minutes, the vacuum is probably gone and so will allow the pump to draw fuel again.
There is also a minor chance the coil is overheating and shorting internally. Runs for a short time then shorts. Cools off and is able to start again. Condenser might do the same if really old but would a 1/2% chance of this happening. This is not the first place I would look but if you cannot seem to get the problem fixed after significant time spent on the fuel system, I would look here.
I have had several squarebacks in the late 70s and 80s. Really liked them. My wife had a 69 I built with a 1776cc engine, 286 degree cam, merged headers, centrifugal distributor and dual 40mm DCNF Webers. Performed really well over hills, even with four people, as the power really came on after 3K RPMs. Love those flat 4s.
A possibility I would look at first would be the metal fuel line entering the front shroud which might be too close to the #3 exhaust causing the fuel to boil in the gas line, starving the pump. Make sure the metal line and any other flexible lines do not get too hot or touch any part of the engine heads or case.
If the engine is starving for gas after 12 minutes idling, it should starve after a minute or so of driving, if it is a fuel delivery problem. If you can drive it for 12 minutes then it stops, it might be a vacuum forming in the fuel tank because the vent line is blocked. This would probably only happen if the fuel tank is fairly full and the gas cap is sealing correctly. In this case the fuel pump cannot overcome the vacuum in the tank. Remember the fuel pump only creates about 3psi of pressure to the carb so it is not very powerful. After 15 minutes, the vacuum is probably gone and so will allow the pump to draw fuel again.
There is also a minor chance the coil is overheating and shorting internally. Runs for a short time then shorts. Cools off and is able to start again. Condenser might do the same if really old but would a 1/2% chance of this happening. This is not the first place I would look but if you cannot seem to get the problem fixed after significant time spent on the fuel system, I would look here.
I have had several squarebacks in the late 70s and 80s. Really liked them. My wife had a 69 I built with a 1776cc engine, 286 degree cam, merged headers, centrifugal distributor and dual 40mm DCNF Webers. Performed really well over hills, even with four people, as the power really came on after 3K RPMs. Love those flat 4s.
I agree with 67 bug on both opinionsA possibility I would look at first would be the metal fuel line entering the front shroud which might be too close to the #3 exhaust causing the fuel to boil in the gas line, starving the pump. Make sure the metal line and any other flexible lines do not get too hot or touch any part of the engine heads or case.
If the engine is starving for gas after 12 minutes idling, it should starve after a minute or so of driving, if it is a fuel delivery problem. If you can drive it for 12 minutes then it stops, it might be a vacuum forming in the fuel tank because the vent line is blocked. This would probably only happen if the fuel tank is fairly full and the gas cap is sealing correctly. In this case the fuel pump cannot overcome the vacuum in the tank. Remember the fuel pump only creates about 3psi of pressure to the carb so it is not very powerful. After 15 minutes, the vacuum is probably gone and so will allow the pump to draw fuel again.
There is also a minor chance the coil is overheating and shorting internally. Runs for a short time then shorts. Cools off and is able to start again. Condenser might do the same if really old but would a 1/2% chance of this happening. This is not the first place I would look but if you cannot seem to get the problem fixed after significant time spent on the fuel system, I would look here.
I have had several squarebacks in the late 70s and 80s. Really liked them. My wife had a 69 I built with a 1776cc engine, 286 degree cam, merged headers, centrifugal distributor and dual 40mm DCNF Webers. Performed really well over hills, even with four people, as the power really came on after 3K RPMs. Love those flat 4s.
It could be anything, coil, carbs fuel supply etc. Quite a common fault on points operated distributors is condensor failure. A new set of points and condensor would be my first replacement.
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