I am working on a 77 Custom Deluxe 30 w/ HEI ignition. It has a backfire through the carb. Happens when I crack the throttle, and is worse when the truck is on the road. Does not like over about 1600 RPM. Replaced the fuel filter w/o a difference. Put a timing light to it and found the timing mark to be "jumping around" at idle. I have checked the RV forumns and the thought is to replace spark plug wires, next cap, next rotor. Also, possibly replace timing set. Any thoughts???? Anyone know what initial timing is for this engine???

Also, engine has tick that seems to come from right side. Put a screwdriver to engine and found the noise more pronounced at where #4 and #6 intake meets head. What's the story with a flapper valve possibly creating this noise?? Man, I hate to think I have VALVE trouble. If so, what is the best way to isolate it.

Sorry a truck dude is on this forumn. But, I have run out of ideas on where to look. Thanks in advance for your help.