Timing retarding 2* after installing crank trigger
 

I'm running a 7AL-3 Black Ignition' Just installed a sbf used crank trigger..... Set the sensor with one of the magnets, locked on 30* and turned the dist to #1 ... Fired right up. Looks rock solid till I rev the engine, then it retards 2 degrees.... I have tried everything with no luck... The sensor wires match the wires going to the 7AL-3 , but reversed them and timing advanced 20 * so switched back... Crank trigger wheel is on right side' with arrow on outside turning clockwise... Sensor is about 50 airgap from trigger wheel..
Things I tried below...
Tried another but used sensor
Tried another crank trigger wheel
Tried a used digital 7
Just tried a new out of the box digital 7
Have 0 chips in retards not using and ran gnds also
Ran gnds from aluminum heads to frame
Using flaming river self powered regular timing light ' but tried 3 others
Put light on # 6 cyl and still same thing
Even though I have heavy gnd's and hot at rear and front of car, ran 10 gauge + & - from 7AL3 to batt
Intsalled a new I had laying around , shielded cable from sensor to ign box...
Timing was off 2* on balancer when I first built the motor' went back yesterday with a dial indicator in #1 cyl and made sure it was still the same...
MSD has went out of their way trying to help me but said they didn't know what else to try..
Anyone here ever have this problem ?? thanks

Re: Timing retarding 2* after installing crank trigger
 

"Set with one magnet"? Did you center it or use leading edge? On magnet old Moroso that was method. Putting at starting pt w loose timing belt? Did you use other style timing light too?

Re: Timing retarding 2* after installing crank trigger
 

I centered it with one of the magnets and locked it down on 30*
Then pointed the rotor toward #1
I did have to moved the sensor a few times to get it dead on 30....
Then when u go back and check it, the censor and magnet is not centered with each other.... MSD said that was normal.... When it fires its dead on 30* still as can be till you rev it up and then it retards 2*

Re: Timing retarding 2* after installing crank trigger
 

Just shot a video clip, you can see what its doing...Starts retarding around the 12 sec mark a few times when I rev it


https://www.youtube.com/watch?v=ONZNCOceZ4Y

Re: Timing retarding 2* after installing crank trigger
 

you using a timing chain or a gear drive? FED 387

Re: Timing retarding 2* after installing crank trigger
 

Chain

Re: Timing retarding 2* after installing crank trigger
 

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
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Re: Timing retarding 2* after installing crank trigger
 

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

Re: Timing retarding 2* after installing crank trigger
 

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?

Re: Timing retarding 2* after installing crank trigger
 

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...

Re: Timing retarding 2* after installing crank trigger
 

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...

Re: Timing retarding 2* after installing crank trigger
 

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

Re: Timing retarding 2* after installing crank trigger
 

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

Re: Timing retarding 2* after installing crank trigger
 

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.

Re: Timing retarding 2* after installing crank trigger
 

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.

Re: Timing retarding 2* after installing crank trigger
 

Your observations are correct, but your conclusions are incorrect. The spark (ie. coil) is being signaled by the crank trigger but the spark generated by the coil is being delivered by the distributor, and the timing light is being triggered by the spark in the wire, not the crank trigger. While the change is small, there is a change. The reason you don't see change with the light is that the spark is jumping the gap to the terminal and with the speed of electricity, and the width of the tab on the rotor you are not going to detect that with the flash of the timing light. But, since the spark is being delivered to the terminal in the cap via the tab on the rotor...if it gets there sooner or later...the timing IS changing.....what you are doing is moving it from the center of terminal slightly, yes it is still firing the light the same, because the spark is still jumping the gap. If you were to move the rotor phasing to the edge of the conductive plane, then try moving the distributor you would find that you start killing the cylinder....the spark would now be getting there to late and the gap is too large for it to jump. Granted, this is extreme, but it will show you that moving the distributor will affect timing. If you were to use a scope rather than a timing light to look at the signals in real time, you would see the timing change as well.