Engine Backfire when hot
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Mountain Pass
Joined: Nov 2018
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Engine Backfire when hot
I have a 1973 Ranchero Q code engine 351. It is the original engine as I have installed a new timing chain and gears and could see the 4 bolt rod for number one cylinder. It has the Edelbrock carb installed and a pressure regulator for the fuel line set at 4 psi to prevent the carb from overflowing the bowls. When cold I get 50 psi oil pressure on a gauge which was checked by a shop and was accurate. As you run then car and it gets warm, around 180 to 190 on the water temp I get only 15 to 20 psi at 1000 rpm and 25 to 30 at 2000 rpm on the oil pressure gauge. A new problem which started this last weekend was it started to backfire thru the muffler. It only happened when I was trying to accelerate from a stop but the last one was very loud and blew out the side of the muffler which was pretty rusty anyway. Does this sound like a fueling issue to you or some other issue with the motor. It has 175,000 miles on it and runs great when cold. Les
Cargo Master
Joined: Sep 2005
Posts: 2,954
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to blow your muffler you have to have too much unburned fuel in that side of the engine,(assuming dual exhaust). Pull the plugs and do a compression test, look for rich plugs, check the wires. Blame the carb last.
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Mountain Pass
Joined: Nov 2018
Posts: 115
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Quick Update to this, It appears that the points replacement unit inside the distributor was cutting out when hot. I have replaced with points and the problem has gone away but i still need to tune the engine tp determine is it was the only problem.
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