smokinnjokin
Well-Known Member
Gentlemen,
Had this problem on a thread long ago, figured I would just start fresh and lay out everything.
1967 satellite 2-door; 727 with 3.23 sure grip and 360.
Cam is comp xe 262; Edelbrock 500cfm carb and performer rpm manifold. Full tti headers and 2.5 exhaust system.
Motor is a freshly rebuilt (by a 3rd party machine shop), low compression 360 with pertronix and halifaxhops recurved oem distributor.
Runs beautifully, starts right up, plugs are spotless and the car pulls hard. Been driving for about 6 months now and trying to solve the issue:
The timing jumps back and forth by about a 5 degree sweep. At idle, it is very noticeable; its very hard to get an accurate reading because it Varies constantly between 2 reading about 5 degrees apart. Note: it does not 'wander' gradually between timing marks, but rapidly jumps back and forth. The issue is consistent across the rev range, but is most noticeable at idle with the flashes slowed down. Because of this variation in timing, I have to keep the timing pulled back to 13/33 to avoid detonation (remember, this is an auto with no mid-throttle lockdown on the trans linkage) even though the motor really wants to run beautifully at 16/36. Based on what the light is showing, actual timing is varying by a solid 5 degrees so at full throttle.
Here's the troubleshooting I have done. Sent the distributor back to Ray to check over and spin on his machine. New cap, rotor, wires. Everything checks out, no change. Changed the distributor intermediate shaft, fearing slop. No change. Ignition system seems solid. Again, great idle, clean running and fires right up no drama.
So that leaves me suspecting the timing chain or gear; it does not appear they used a tensioner because there is some delay when turning over by hand for the distributor rotor to turn. What I don't understand is that if there was somehow excessive slop in the chain, why would the timing jump cleanly back and forth... wouldn't it wander around gradually as the chain flexed under load?
What should I check next here, I am scratching my head.
Had this problem on a thread long ago, figured I would just start fresh and lay out everything.
1967 satellite 2-door; 727 with 3.23 sure grip and 360.
Cam is comp xe 262; Edelbrock 500cfm carb and performer rpm manifold. Full tti headers and 2.5 exhaust system.
Motor is a freshly rebuilt (by a 3rd party machine shop), low compression 360 with pertronix and halifaxhops recurved oem distributor.
Runs beautifully, starts right up, plugs are spotless and the car pulls hard. Been driving for about 6 months now and trying to solve the issue:
The timing jumps back and forth by about a 5 degree sweep. At idle, it is very noticeable; its very hard to get an accurate reading because it Varies constantly between 2 reading about 5 degrees apart. Note: it does not 'wander' gradually between timing marks, but rapidly jumps back and forth. The issue is consistent across the rev range, but is most noticeable at idle with the flashes slowed down. Because of this variation in timing, I have to keep the timing pulled back to 13/33 to avoid detonation (remember, this is an auto with no mid-throttle lockdown on the trans linkage) even though the motor really wants to run beautifully at 16/36. Based on what the light is showing, actual timing is varying by a solid 5 degrees so at full throttle.
Here's the troubleshooting I have done. Sent the distributor back to Ray to check over and spin on his machine. New cap, rotor, wires. Everything checks out, no change. Changed the distributor intermediate shaft, fearing slop. No change. Ignition system seems solid. Again, great idle, clean running and fires right up no drama.
So that leaves me suspecting the timing chain or gear; it does not appear they used a tensioner because there is some delay when turning over by hand for the distributor rotor to turn. What I don't understand is that if there was somehow excessive slop in the chain, why would the timing jump cleanly back and forth... wouldn't it wander around gradually as the chain flexed under load?
What should I check next here, I am scratching my head.