Hey boys, I have unfortunately detonated another engine (being A15 turbo engine on 11psi) and its clearly an issue with the mechanical advance on the electronic dizzy as its not locked I'm not using vaccum advance at all and the initial static timing is 7 degrees but still pinging and has unfortunately done rings again

I need a hand on how to lock this dizzy I have not done it before I have half an idea to pull apart top part with trigger and rotor button then the mechanical advance is below knock out the pin and pull apart but unsure what to do with the weights and springs can I leave the springs on it and just do a quick spot weld on the advance and lock it then just set my static timing for around 16-20 degrees and run tests to confirm the timing is right with out it pinging or do I need to lock the weights and remove the springs and weld to certain point

I have also heard of using stainless wire and removing the springs and tying off the advance

All help would be great I cant be replacing rings and pistons again don't want to end up #OOPS#ing a block and beyond a hone fix

Yes, you can use vacuum advance, since by design it won't have any effect at heavy throttle

The mechanical advance is what is needs to be limited, yes leave the springs on it and just do a quick spot weld on the advance, that alone will lock the advance. Then when you install the distributor, wherever you set the timing to, it will not change

Loosekid,google CB Performance black box,I have a brand new one un used and locked dissy here that was installed but never used,if interested let me know.Cheers

Yes, that's a much better way to go, the Black Box makes a lot more HP for a street car than locking the advance. Locking it means it will only run optimal at high-RPM, full boost


For a no-cost method, better than locking is limiting the advance. Here is a Datsun distributor with the advance slots welded up to severely limit the amount of advance (nearly locked). You'll make more HP at various RPMs by giving the turbo engine a little advance, but not enough to kill it


Yes, that's JB-weld there. The advantage is you can grind the slots longer if you need more advance. I'd shoot for 23 degrees total to start with (instead of the stock 30-34 degrees). You can add more as you test it, either on a dyno or by using "detonation cans". Remember, the more advance, the more HP. But don't let it detonate

Quote:After a distributor mod like above:
* set your "initial timing" to the stock 7 degrees for easy starting and good off-idle performance
* start the engine, set the hand brake, put it in neutral and rev it to 4800 RPM. Check to see what the timing reads. 23 degrees should be safe for up to 15 lbs boost

Do a 2nd-gear high-RPM full boost run and a 3rd-gear full boost mid-RPM run -- if it doesn't ping/detonate, then advance the distributor (rotate it) to get a couple more degrees advance, then test again. Keep doing that until you hear pinging, then back off 1 degree. Check your timing. Put it back at 7 degrees and modify the slots until it will advance all the way to your boost-optimal timing.

The only downside is this doesn't handle varying boost levels (like highway cruising vs full-boost acceleration) but for that you'll need an ECU or programmable ignition controller like the Black Box or MSD 6AL-2