Timing retarding 2* after installing crank trigger

[1968 SS]

Normal operation of MSD 7AL-3 ignition box to retard timming up to 4*
Set timming at 3,000 RPM as per MSD instructions.

Brian
.

[FED 387]

Most chain driven cams will retard when you rev the engine and then let the RPM's come back down its the play/slack in the chain doing it---just like what yours is doing--- suggestion---- rev the engine to say 4000 RPM -5000 RPM hold the rpm steady then hold the timing light on the balancer mark move your distributor or pick up on the crank trigger whatever you do to set the timing to the desired timing -- tighten down your pick up or distributor---then recheck the timing again at say 4000 see if it stays where you set it or if it moves- revving and then letting the RPM go up and down allows the chain to advance and retard the timing as the chain loosens and tightens--- make sense??? FED 387

[pmrphil]

The timing chain has nothing to do with timing when using a crank trigger, only affects the position of the rotor. I just adjusted for it so it was correct at RPM. Sure does make you wonder, huh?

[colormebad]

I just noticed the crank trigger bracket is Vibrating pretty good when I rev the engine to a certain rpm, which is causing the timing mark not to be rock steady as it should .... Now I wonder if that is also where the 2* retard is coming from... Just ordered a bracket , so I can mount it to the motor instead of the motor plate.... This was a used bracket that someone used on the driver side, and had cut one side off some... The bracket I made to mount the bracket that came with the kit to the motor' Is and looks strong, I don't see how its doing what I see with my eyes.... I still hope its not a problem with the balancer...The bracket that mounts to the stock location timing pointer , will be here later I hope...

[FED 387]

SORRY -- missed that part about the trigger was just looking at the pointer and timing mark---FED 387 You are correct

[Ron Finney]

The statement that the distributor has nothing to do with the timing when using a crank trigger is ridiculous. How do you think the spark gets to the plug wires??? oh yeah, that is also where the timing light gets it trigger..... It is correct that the point of the crank trigger is to get an accurate timing signal by taking the timing chain variation out of the equation. However, that is only the pickup side of the equation. Unless you are using DIS, the distributor is still in the equation and it is driven by the timing chain which does have slack and does stretch. Every chain driven engine will have 1-2 degrees of slack which will retard the timing...if it gets much more than 3-4 then time for a new chain. That is why MSD is telling you to time the motor at 3000 or more, you have the slack out of the chain at that point. Your vibrating bracket doesn't sound good either, but I think you are trying to fix normal operation if you are looking at timing in an unloaded (idle) to loaded (high RPM) comparison.

[pmrphil]

Originally Posted by Ron Finney

The statement that the distributor has nothing to do with the timing when using a crank trigger is ridiculous. How do you think the spark gets to the plug wires??? oh yeah, that is also where the timing light gets it trigger..... It is correct that the point of the crank trigger is to get an accurate timing signal by taking the timing chain variation out of the equation. However, that is only the pickup side of the equation. Unless you are using DIS, the distributor is still in the equation and it is driven by the timing chain which does have slack and does stretch. Every chain driven engine will have 1-2 degrees of slack which will retard the timing...if it gets much more than 3-4 then time for a new chain. That is why MSD is telling you to time the motor at 3000 or more, you have the slack out of the chain at that point. Your vibrating bracket doesn't sound good either, but I think you are trying to fix normal operation if you are looking at timing in an unloaded (idle) to loaded (high RPM) comparison.

Try checking your timing and then rotate the distributor a bit (either direction) and you will see that timing doesn't change (if you're using a crank trigger) the only thing that changes is the position of the rotor in relation to the plug wire tower in the cap. It has no effect on timing events until you turn the dist so far that the spark is transferred to an adjacent tower. The spark is signalled by the trigger, not the dist.

[colormebad]

Originally Posted by pmrphil

The timing chain has nothing to do with timing when using a crank trigger, only affects the position of the rotor. I just adjusted for it so it was correct at RPM. Sure does make you wonder, huh?

That's what 2 MSD techs told me... Its hard for me to 100% believe but I will find out one way or another... Its down to this bracket needing to be bolted to the motor instead of the motor plate, and with a new bracket, or the balancer...

[colormebad]

Originally Posted by 1968 SS

Normal operation of MSD 7AL-3 ignition box to retard timming up to 4*
Set timming at 3,000 RPM as per MSD instructions.

Brian
.

Tech just told me a few days ago, set it where I want it and it should not retard .... Did the same thing with a brand new digital 7