Setting Timing on a Modified 52 Panhead

[jbucking]

I have a 52 Panhead that was modified by the prior owner with a S&S Carb, S&S cases, etc, etc. I do not know what internal modifications (cams) have been made. The distributor is a later automatic advance unit. When I set the timing using the timing light using the timing mark and the "observation hole" I get a lot of backfiring at higher rpms especially from the front cylinder. I then retarded the timing a bit by just turning the distributor clockwise and the back firing goes away, but I realize if I retard the ignition too much that the motor will likely over heat, etc and lead to other complications.

Is setting the timing "by ear" the way to go, or am I missing something ? Any guidance will be appreciated. Thanks !

[fourthgear]

The front cyl. timing mark should be in the middle of the timing hole when timing an auto adv. unit, with a strobe type timing light or static timing, should make sure you have the right timing mark.

[jbucking]

To the best of my knowledge the 52 pan only has a front cylinder timing mark, and no rear cylinder timing mark (it showed up on later models). If it has both then that could be the issue. Should it have just one front cylinder timing mark, or does it have front and rear marks ? How would you tell the front and rear marks apart if it has both ? Thanks, John

[pandit]

No.
Flywheel is not marked for rear cylinder timing until Engine No. 61FLH 7987.

[fourthgear]

The referance to the front timing mark was just generic , you never know what fly wheel type or year or modifacations to them some one has . (You did say a modified motor)

Are you setting the timing( with a strobe type timing light ) @ idle or @ 1500 rpm's as to make sure the advancing system is fully advanced ? Are you sure the advancing system is advancing the point lobe ? Condenser OK ?

I use the static methed of timing with point type ign. systems. I use a strobe type timing light for elctronic ign. systems , but it will work for a point type .