Timing Issue
October 6th, 2017, 04:53 PM
#1
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Thread Starter
Join Date: May 2010
Posts: 87
Timing Issue
1965 442, all stock 400 - newly rebuilt - except using msd ready to run distributor (no box).
With the vacuum advance plugged, set the initial timing to 10°. I have two timing lights, one old "Sun" inductive model, and a new digital pep boys model. Both read the same at idle.
When I rev the engine to check total timing (say 3200 RPM), the timing mark does not move much with the pep boys model, maybe a few degrees, and is very steady. This is with the advance on the light set to zero. If I set the advance to 34°, the timing mark moves down, but once again, revving the engine does not move the timing mark towards the zero, it stays put.
With the old Sun model, the timing mark slowly advances, then starts jumping around all over the place. Very erratic.
The MSD has adjustable springs, so I currently have the light silver and light blue spring. The only lighter combination is two light silver springs.
I also tried the light silver and the heavy silver, with same results.
What the heck is going on here? Are the timing lights not working properly, or is there something wrong with the MSD centrifugal advance? The weights seem to move freely (not hung up).
When I drive the car it is very peppy, can chirp the tires each shift (and its automatic).
When I plug the advance back in, it takes the initial from 10 to 20 degrees, so the advance is working (it is hooked to manifold vacuum since that is all there is on the stock carb from 65).
Any thoughts would be appreciated.
With the vacuum advance plugged, set the initial timing to 10°. I have two timing lights, one old "Sun" inductive model, and a new digital pep boys model. Both read the same at idle.
When I rev the engine to check total timing (say 3200 RPM), the timing mark does not move much with the pep boys model, maybe a few degrees, and is very steady. This is with the advance on the light set to zero. If I set the advance to 34°, the timing mark moves down, but once again, revving the engine does not move the timing mark towards the zero, it stays put.
With the old Sun model, the timing mark slowly advances, then starts jumping around all over the place. Very erratic.
The MSD has adjustable springs, so I currently have the light silver and light blue spring. The only lighter combination is two light silver springs.
I also tried the light silver and the heavy silver, with same results.
What the heck is going on here? Are the timing lights not working properly, or is there something wrong with the MSD centrifugal advance? The weights seem to move freely (not hung up).
When I drive the car it is very peppy, can chirp the tires each shift (and its automatic).
When I plug the advance back in, it takes the initial from 10 to 20 degrees, so the advance is working (it is hooked to manifold vacuum since that is all there is on the stock carb from 65).
Any thoughts would be appreciated.
October 6th, 2017, 07:11 PM
#2
72 Olds CS
Join Date: Jun 2011
Posts: 6,657
The vac advance is separate from the mech advance.
the sun light sounds like its not working correctly.
It also seems like your not getting any mech advance. w the pep light set to 34 the mark will go way down (maybe not visible) as you rev it should move closer to 0. I would try the 2 lightest springs and see what you get.
w my HEI i found the aftermarket moroso kit lightest springs would allow mech advance at idle so i had to use 1 light 1 mid spring this didnt advance at idle but to be 'all in' required 4k ish rpms I would hope MSD would provide springs that dont advance at idle so maybe your just in need of lighter springs.
Do you know what the max vac and mech advance are advertised at ?
the sun light sounds like its not working correctly.
It also seems like your not getting any mech advance. w the pep light set to 34 the mark will go way down (maybe not visible) as you rev it should move closer to 0. I would try the 2 lightest springs and see what you get.
w my HEI i found the aftermarket moroso kit lightest springs would allow mech advance at idle so i had to use 1 light 1 mid spring this didnt advance at idle but to be 'all in' required 4k ish rpms I would hope MSD would provide springs that dont advance at idle so maybe your just in need of lighter springs.
Do you know what the max vac and mech advance are advertised at ?
October 7th, 2017, 04:43 PM
#4
Registered User
Thread Starter
Join Date: May 2010
Posts: 87
Timing Issue Solved
Okay, so solved the timing issue I described above.
Turned out the weight mechanism in the distributor had a bad weld in the center (high spot), which was rubbing against the rotor and preventing the timing from functioning properly. It only did this when the rotor was tightened down, so I never noticed it. When I had checked the spring action previously it was either with the rotor off or the rotor on but not tightened all the way. It was only that last bit of tightening that caused it to rub.
I filed down the bad weld and boom, the weight mechanism no longer rubbed and was able to advance normally.
I guess you can't expect a $400 distributor to be built properly.
SO after 3-4 days of scratching my head, with two other mechanics looking at it, and numerous phone calls to MSD, problem solved. And found it by accident really.
I was ready to go out and buy yet another timing light as everyone was saying the timing light must be bad. Well, my digital pep boys timing light seems to work just fine when the distributor is actually working.
Turned out the weight mechanism in the distributor had a bad weld in the center (high spot), which was rubbing against the rotor and preventing the timing from functioning properly. It only did this when the rotor was tightened down, so I never noticed it. When I had checked the spring action previously it was either with the rotor off or the rotor on but not tightened all the way. It was only that last bit of tightening that caused it to rub.
I filed down the bad weld and boom, the weight mechanism no longer rubbed and was able to advance normally.
I guess you can't expect a $400 distributor to be built properly.
SO after 3-4 days of scratching my head, with two other mechanics looking at it, and numerous phone calls to MSD, problem solved. And found it by accident really.
I was ready to go out and buy yet another timing light as everyone was saying the timing light must be bad. Well, my digital pep boys timing light seems to work just fine when the distributor is actually working.
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