While attending this years Nationals at Novi and driving to the Milford Proving Grounds we encountered an issue with our 67 Coupe. When cold the car runs perfectly but after 10 miles or so and up to full operating temperature the engine no longer wants to hold an idle and will stall out. This is evident soon as you begin to decelerate as the engine stumbles and if you don't blip the throttle it dies.
As we were driving the approach to the Milford grounds I found the car becoming increasingly balky and dropping down gears and keeping the revs up kept it somewhat happy. When we entered the grounds the caravan slowed to a near crawl this was the kiss of death as the car just wouldn't run and as we pulled onto the "black lake" she died out. After about 20 minutes it fired up again and we were able to get a spot in last row of the line but again when we were about to caravan out it wasn't co-operating and refused to hold an idle. We flat bedded it back to the trailer.
My initial thoughts were that we were encountering fuel perculation however when trying to start the engine it would give a lean pop from the centre carb. One of the GM guys indicated that he felt my fuel pump may not be producing the correct pressure which he indicated 435's want not less than 9-1/2 lbs . This seems like a lot and my numbers correct stock pump delivers 6 PSI per my gauge when tested today. This was with engine warmed to 200 degrees on the dash gauge and 189 degrees per my Raytech on the upper rad hose.
I'm running a 50/50 mix of 101 Av-Gas and 91 Octane Shell unleaded fuel.
I've taken the carbs off, checked and replaced all three fuel filters, checked float levels etc etc. All seems fine.
Can any of you please verify the pump pressure requirement and can the pump I have be modified to deliver the necessary pressure ? If so who does this work.
Any other suggestions would be appreciated. I want to drive and enjoy the car !
As we were driving the approach to the Milford grounds I found the car becoming increasingly balky and dropping down gears and keeping the revs up kept it somewhat happy. When we entered the grounds the caravan slowed to a near crawl this was the kiss of death as the car just wouldn't run and as we pulled onto the "black lake" she died out. After about 20 minutes it fired up again and we were able to get a spot in last row of the line but again when we were about to caravan out it wasn't co-operating and refused to hold an idle. We flat bedded it back to the trailer.
My initial thoughts were that we were encountering fuel perculation however when trying to start the engine it would give a lean pop from the centre carb. One of the GM guys indicated that he felt my fuel pump may not be producing the correct pressure which he indicated 435's want not less than 9-1/2 lbs . This seems like a lot and my numbers correct stock pump delivers 6 PSI per my gauge when tested today. This was with engine warmed to 200 degrees on the dash gauge and 189 degrees per my Raytech on the upper rad hose.
I'm running a 50/50 mix of 101 Av-Gas and 91 Octane Shell unleaded fuel.
I've taken the carbs off, checked and replaced all three fuel filters, checked float levels etc etc. All seems fine.
Can any of you please verify the pump pressure requirement and can the pump I have be modified to deliver the necessary pressure ? If so who does this work.
Any other suggestions would be appreciated. I want to drive and enjoy the car !

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