I have a ZZ502 crate motor with only about 150 miles on it. It has a Holley 850 and Hooker Headers with a Flowmaster exhaust. The headers have three normal primary tubes and one that is a two piece that wraps around the frame.
The motor starts fine and runs great with only two small problems. First, the engine backfires occassionally (once every minute or two) when idling. The backfire is only out of the right side of the exhaust and seems to happen more often once the engine is warm. This also happens sometimes while driving, but only at low RPM with the trottle shut. Second, the engine sometimes (maybe 1 out of 5 times it's driven) diesels for a few seconds after the ignition is turned off.
The spark plugs and exhaust gaskets are new, and I have verified that the header bolts are all tight. I have checked the timing and it is at 8 degrees at idle.
I am thinking that these symptoms might be due to a small exhaust leak and/or carbon deposits on the valves, but I am looking for some other options before I start taking things apart.
The motor starts fine and runs great with only two small problems. First, the engine backfires occassionally (once every minute or two) when idling. The backfire is only out of the right side of the exhaust and seems to happen more often once the engine is warm. This also happens sometimes while driving, but only at low RPM with the trottle shut. Second, the engine sometimes (maybe 1 out of 5 times it's driven) diesels for a few seconds after the ignition is turned off.
The spark plugs and exhaust gaskets are new, and I have verified that the header bolts are all tight. I have checked the timing and it is at 8 degrees at idle.
I am thinking that these symptoms might be due to a small exhaust leak and/or carbon deposits on the valves, but I am looking for some other options before I start taking things apart.