posted October 08, 2003 01:36 PM
Changed motors for the end of the year specials, 355 to a 377, and developed a popping sound out of the header(s). It is a new motor and the valve springs were checked for pressure during installation.
Started out thinking it was ignition, so we changed plugs, plugwires, battery, had distributor checked and freshened, etc. and the motor still pops. Also, put new power valves and needle & seats in carb.
The only thing that affected the noise, was jets. When we jetted down, the popping got better, but you could tell the motor wasn't as fast on the straights. When we jetted up, the popping got worse, but the motor was faster.
Overall, the motor pops intermittently all the way around the track, but gets really bad at the end of the straight above 7000 rpm, and actually makes the power drop off.
Asking for ideas from you guys here on the forum. Thinking it could be a fuel volume/delivery problem. We run a belt drive vane pump, and our fuel lines were two seasons old, and could be developing a collapsed line as well?