Holley Dual Sync

To finish up the EFI install a Holley Dual Sync distributor was added.  Its pretty much plug and play with the Holley Sniper.

The wiring had been prepared when installing the sniper EFI.  Only had to remove coil input wire from the ignition coil.  Then connect coil driver in its place.

In order to align the Dual Sync distributor the crank needed to be rotated to 50 degrees before top dead centre (on compression stroke).  My harmonic balancer only had 3,6,9,12 degrees marked out. The balancer is 6.375″ diameter so to find 50 degrees used a simple equation to mark up some tape with appropriate positions. Also added 6 & 12 degrees to verify the size.  ( had marked up for 7″ & 8″ balancers as I didn’t know how big the balancer was )

Once the crank was positioned correctly set the distributor was dropped in.  All went smoothly until I tried to connect up the spark plug wires.

A bit of a discovery for me, the spark plug wires from the original setup didn’t fit on the new distributor, doh!  I didn’t know there were different types.  Original was stock style plug and the new one is HEI (high energy ignition).  So had to order new spark plug wires.

New spark plug wires; the set is really nice and has spark plug number on each wire which is handy.  Only had to cut the ignition coil wire to length and attach the correct connector.  Really like the new colour suits the engine.
I rotated the distributor so the number one spark plug position was at the rear.  This lines up better with the spark plug wires lengths.

Final setup was quite simple, set the Holley Sniper to link to the Holley Dual Sync.  Then set the timing to a static number.  I chose 12 degrees as there is a marker on the balancer at that point.  Initially, the timing was checked on the starter with the fuel pump disabled.   After that was confirmed to be ok the fuel pump was enabled and the engine started.  It started right away.

Next stage was to set the static timing with the engine running and verify the timing position on the balancer.  After that, the engine had to be revved up to verify that the timing stays in place at higher RPM.  The engine would retard a little with higher RPM. So had to increase the inductive delay in the settings to compensate.  With a few iterations got the inductive delay just right and it stayed on the 12 degrees static timing at any RPM.

It’s so much smoother now the new distributor.  I’m looking forward to some better weather so I can go out for a drive.

Audio Samples

Took an audio recording before and after the distributor install, click below to hear the difference.  Each recording starts with exhaust flaps closed, then open.

Before Holley Dual Sync install

After Holley Dual Sync install

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