703MGB
Senior Member
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May 29th a beautiful sunny day in Montreal. Kids are in the pool. There is a British meet in Montreal in a park on the lake so I decided to go there to take a peek just after lunch.
Stick the MG in 4th gear at 80 miles + an hour on highway 40. Engine revving happy at 4700 rpm.
Then loud mechanical sound followed by a loud bang. Engine went totally wrong. Can’t even leave the highway I had to stop on the right shoulder. Waited 15 minutes for the police and tow truck to show up. When you drive at 65 we usually think it is slow but when you are stopped on the shoulder in an MG let me tell you that cars and trucks passing at 65 look and fell very fast.
Got home in the tow truck only thinking about this new engine that will be required.
Once home I opened the hood, removed the valve cover to see that the exhaust valve on cylinder one has its pushrod off the rocker. I then removed spark plug one to insert a magnet in order to determine the level of destruction. No results, no metal, no holes.
Ok what’s wrong? I repositioned the pushrod back in place and adjusted clearance. Fired up the engine to a very nice rumble at 800 rpm. YES YES by engine is saved!!!!!
Further analysis revealed that pushrod number 1 is bent. Why is it bent you may ask. Well my exhaust valves are stellite and are heavier then the regular ones. My valve springs are the single model. What is happening is when the engine is not hot enough it suffers from valve float and at 4700 rpm one pushrod just went out of it’s socket.
Next step will be a new set of pushrod and a change to double springs on the valves.
A bad day that ended not so bad.
Stick the MG in 4th gear at 80 miles + an hour on highway 40. Engine revving happy at 4700 rpm.
Then loud mechanical sound followed by a loud bang. Engine went totally wrong. Can’t even leave the highway I had to stop on the right shoulder. Waited 15 minutes for the police and tow truck to show up. When you drive at 65 we usually think it is slow but when you are stopped on the shoulder in an MG let me tell you that cars and trucks passing at 65 look and fell very fast.
Got home in the tow truck only thinking about this new engine that will be required.
Once home I opened the hood, removed the valve cover to see that the exhaust valve on cylinder one has its pushrod off the rocker. I then removed spark plug one to insert a magnet in order to determine the level of destruction. No results, no metal, no holes.
Ok what’s wrong? I repositioned the pushrod back in place and adjusted clearance. Fired up the engine to a very nice rumble at 800 rpm. YES YES by engine is saved!!!!!
Further analysis revealed that pushrod number 1 is bent. Why is it bent you may ask. Well my exhaust valves are stellite and are heavier then the regular ones. My valve springs are the single model. What is happening is when the engine is not hot enough it suffers from valve float and at 4700 rpm one pushrod just went out of it’s socket.
Next step will be a new set of pushrod and a change to double springs on the valves.
A bad day that ended not so bad.