General engine tech -- Drag Racing to Circle Track
Alan Roehrich wrote:You'll find that this can happen with electronic ignition systems, especially magnetic triggered systems.
Recently noticed this on a big block that had a 7AL-2 and an MSD distributor. We figured swapping to a crank trigger would solve it. It did not. The timing still dropped back, and still varied slightly.
What I ended up doing was repairing and rerouting the magnetic trigger cable. After that, the timing did not move.
I suggest using a shielded cable, routing it carefully to keep it away from anything that might upset the signal, and even grounding the shield on both ends.
- Posts: 195
- Joined: Sun Feb 26, 2012 4:07 pm
It's a magnetic trail related issue, Gm and ford distributors have it as well as msd's, the only way you won't see it is if you use a hall sensor. The good efi boxes allow you to correct/setup for spark delivery lag time, msd knows about it and the majority of their newer boxes corrected for it for a while, not sure if they still do, it's a bigger problem on a distributor due to reluctor spacing than it is on crank trigger, gap changes the value as well.
- Posts: 671
- Joined: Wed Apr 21, 2010 3:35 am
Return to Engine Tech
Who is online
Users browsing this forum: A-Sedan, ap72, Barry_R, Belgian1979, blykins, cuslog, EngineNut, Google [Bot], greywolf, hoffman900, jmarkaudio, kirkwoodken, lorax, MadBill, Mr 408, Ramblerboy, toolmakeron, Vintrcr, wallbrett, wyrmrider and 21 guests