Topic: 1967 428PI Ignition Problem

[kkupec02]

New problem with my 428PI. I recently put in a rebuilt date coded distributor with points and condenser replacing my after market electronic ignition. I also put in a rebuilt correct ignition coil. I don't think it has been even 100 miles since it was done. I went to a cars and coffee about 50 miles away 3 weeks ago. The car ran fine on the way there. On the way home, the car started running horribly and backfiring from the front carburetor. It got worse as we nursed it home. At idle in the garage, it is a rhythmic front carburetor pop every 2 seconds or so. I replaced all plugs and plug wires, reconnected the old ignition coil, changed the points and condenser and checked for vacuum leaks all to no avail. Any ideas as I am running out?

[midlife]

Sounds somewhat like timing went off; have you checked that?  Could be the condenser is bad.

[Bob Gaines]

New problem with my 428PI. I recently put in a rebuilt date coded distributor with points and condenser replacing my after market electronic ignition. I also put in a rebuilt correct ignition coil. I don't think it has been even 100 miles since it was done. I went to a cars and coffee about 50 miles away 3 weeks ago. The car ran fine on the way there. On the way home, the car started running horribly and backfiring from the front carburetor. It got worse as we nursed it home. At idle in the garage, it is a rhythmic front carburetor pop every 2 seconds or so. I replaced all plugs and plug wires, reconnected the old ignition coil, changed the points and condenser and checked for vacuum leaks all to no avail. Any ideas as I am running out?

Check the float level . They may have gotten stuck. His were stuck way low. I would start with giving the adjusting screw on top of each bowl a good wrap with a screwdriver handle to maybe knock it/them loose. I had a friend with somewhat similar symptoms on his 67 GT500 and that was his problem. You may have to take needle and seats out to inspect and clean before installing and setting the float level.

[rockhouse66]

I would put my money on the distributor gear roll pin sheared.  Allowed gear to spin out of place before the remnants of the pin jammed it in a new location.

[lightwtjet]

rockhouse66 (Jim) is an expert at rebuilding/restoring distributors and air pumps. Good luck.

[kkupec02]

Thanks all. This gives me a couple of new things to check out.

[Bob Gaines]

Thanks all. This gives me a couple of new things to check out.

Yes there are any number of possible culprits that can cause similar symptoms. If it were me I would do the easy checks first like checking the site hole on the carb bowl and check the timing with a timing light.

[kkupec02]

I checked all of the "easy" stuff. Then pulled the valve covers and lo and behold, I found a broken push rod. The engine was rebuilt only 900 miles ago by Cobra Automotive. Hopefully they can help me out with some type of warranty or break on the new rebuild.