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Old 04-17-2024, 03:57 PM
darbikrash darbikrash is offline
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Join Date: Oct 2012
Location: So. California
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For the wiring, I started with Holley mini-harness P/N 558-431 and cutoff the 3 pin cam sync connector, replacing it with a 10 pin connector to plug directly into the dual sync. The provided crank trigger connector is plug and play for the Hall effect sensor (P/N 554-118), and the third 10 pin connector plugs right into the Holly main harness. So pretty simple. This mini-harness is about $80, so much cheaper to make your own if you're so inclined.

After initial static timing adjustment by moving the crank trigger bracket, the dynamic timing deviation from idle to 3500 rpm was about 3 degrees, I'll have to check the laptop to see what this was for inductive delay, but not much. I have typically not seen much deviation with crank mounted triggers as you are directly reading the crank, different story on the dual sync - especially if the timing chain is worn. Every engine is different though.

ATI provides magnets on the balancer shell however many and wherever you want. I specified 4 magnets with a 50 degree reference angle, so the first magnet is at 50 degree BTDC. You just align the balancer (and magnet) to 50 deg BTDC on the timing cover "zero" mark, and the 2nd magnet at 90 degrees clockwise is where the sensor is mounted.

This is pretty straightforward, the next step is setting the cam sync to accommodate your reference angle (whatever you choose). If you have a dual sync, whatever you do, do not use the reference angle and just set the balancer there and light up the cam sensor LED. The formula for setting the (dual sync) is [Ref angle]+[90 degrees(pulse angle for V8)]+[Pulse Angle/2]= Crank position in degrees.

If you have a remote crank trigger and use the dual sync, and try and follow the Holley instructions (for dual sync) the engine will not run.

In my case with a 50 degree reference angle, the balancer must be set at 185 degrees BTDC to calibrate the cam sensor LED.

__________________
1964 Catalina 2+2 4sp, 421 Tri-power
1965 GTO, Roadster Shop chassis, 461, Old Faithful cam, KRE heads 305 CFM,
Holley EFI, DIS ignition.
1969 GTO 467, Edelbrock 325 CFM, Terminator EFI
1969 Firebird Convertible
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