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Author Topic:   Popping out Headers/Miss?
Iowamod20
Member
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?

Thanks.

Mud Boy
Member
posted October 08, 2003 03:51 PM
i had the same problem last week check to see if all cylenders are firing mine turned out to be a loose jet was loading up the one side and it had a dead cylender i changed plugs and tightened the jet back up and the pop corn machine sounded alot better. if you don'r have pyrometer just fire it up and let it run for a few minute then squirt some water on each header pipe and see if any takes alot longer to boil the water off that would be the dead one. another thing to look for is on the plugs mine leaned the other side way out so i was fuel fouled on one bank and toast white on the other.


outlawstock17
Member
posted October 08, 2003 07:35 PM
i tend to agree with 17j. it sounds like a carburetion problem. maybe you could borrow a buddy's carb and see if you have the same problem...


Speed Racer X
Member
posted October 09, 2003 10:13 PM

We fought a simular problem for the last few races of the season. It went away when we finally changed the dristributor.

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