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287 Pontiac engine shut down over 175 degree during traffic jam

Giorgio Ancona

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Hi everbody ,


my 1955 GMC 100 with the original 287 Pontiac engine and equipped with a two barrel Bendix WW 23-106B has running problems .


Over 170-175 degree water temp the engine stops running during traffic jam only , I got this problem this year and I renewed the ingniter plugs the ignitor leads and installed a new MSD Blaster 2 coil but nothing helps.


When I open the hood its very hot , could it be that the fuel has gas bubbles and therfore the engine stops?


What I found is a leak at the throttle lever of the carb but it is leaking when the engine is hot only.


Does anybody has an idea or does anyone knows this problem?




Carb leak.jpg

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  • 1 month later...

After changing the ignition coil to MSD2  and all spark plugs to AC Delco R45S I thought the problem is gone but sunday it happens again four times.

What I found out is that it happens during braking while driving down a hill (bridge) and when I did a hard right and immediately a left turn( in a roundabout traffic)  the engine goes off.

From my point of view it seems to be a fuel problem but  the fuel tank was 3/4 full and the fuel filter shows fuel inside.

The last time it happened it took very long cranking before the engine starts again.

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You can’t always trust an old metal fuel line.  Had a 60 Edsel that was constantly “vapor locking” (engine shut down) but turns out there was a cracked fuel line.  

perform a vacuum test on the fuel line. 
disconnect both ends (tank & pump) plug one end (hose and bolt) 

Attach hand vacuum pump at other. (Having the little catch can in the vacuum line is good) 


Then suck down a vacuum. No fuel should enter the catch can and it should HOLD a vacuum.  If fuel comes out then air is coming in.  If it won’t hold a vacuum then air is entering the line.  If air can enter a fuel line the fuel pump can’t draw it up.  

Reasons a fuel line won’t hold vacuum? Cracks and rusty pin holes.  I have never been successful finding these defects with a pressure check, but a vacuum check is extremely sensitive to these issues.  

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