hey just wondering when you switch to a cv carb.and install the crane hi-4 ignition is it a good idea to put the voes unit on it?i noticed in the crane instructions that they recommend it when installing the crane hi-4 ignition.and if so where do you hook up the vacuum line for it?

 

There is, or should be a vacumn port on the top of the intake manifold. It is not 100% nessacary to hook up a voes. I couldn't tell the difference with or without one.

 

ok thanks al.ill try it without it and see how it goes.worse case if it doesnt run good ill put one and try that as i have one right here

 

Never really noticed a difference running a VOES on a shovelhead , unless you'v gone big inches and are detail freak try without you'll be ok . You need a good vacuum gauge and adyno to set one those correctly anyway .

 

I found the VOES to be very useful on my 1980 FX. I installed a Dyna 2000 ignition and the instructions mentioned the VOES, but I had no idea what it was. Looked into it, but couldn't use it.....no vacuum ports. However, I did install a micro switch to activate full timing advance of the Dyna 2000. This was useful for checking timing at idle and for fuel economy. Later I installed a Thunderheader exhaust. But in order to get the motor to run right, I needed to install a CV carb. Once the jetting was set correctly, I decided to install a VOES using the vacuum port on the carb. This allowed me to run in the "economy mode" (full advance) when I wanted, but, when I twisted the throttle hard, the VOES dropped the full advance timing out, and reverted the Dyna 2000 back to the preset timing curve I initially set up. The advantage to all of this is, no more pinging, the timing advance dropped back to a less aggressive ramp up which resulted in a lot more low end torque.

 

When running a HI-4, There is a dip switch for OEM ignition advance curve and Race curve. On race curve, the ignition jumps to full advance off of idle. Using the proper fuel (93 octane), at full advance, and the motor properly timed, there should not be any "pinging" on a street motor with comp ratio's up to 10:1, no matter the size, up to 100".
"Properly timed" is a key issue. Many people center slot the backplate and call it good. Doing this will cause the ignition to be up to 10 degrees off, one way or the other.
On the HI-4, the instructions say to bring the front cylinder up to TDC and adjust the backplate till the red light comes on. This is a static time, and still could be 5 degrees off. This proceedure is just to get the bike started so you can fine tune it. No matter what ignition you run, they have to be fine tuned, with or without VOES, though OEM points are a lot more forgiving.
I've attached a picture of my drag strip queen with a HI-4. 80 cid, 9.75:1 ratio. I know the brake pedal is in the way a little, but you can see the HI-4 is nowhere near center-slot.

 

I agree, I installed a VOES on my '82 with the HI-4 and it was more of a pain in the *** than it was worth, it's in the bottom of my tool box now.

 

I unequivocally can say that my '78-1/2 ran better after I installed the VOES. I had to drill a hole in my intake manifold and press in a little brass nipple to connect the vacuum hose to the VOES. My bike stopped detonating coming off of red lights and it made for a more "streetable" ride. That was in 2000, recently my HI-4 burnt out (running on one cylinder) like the guys predicted in April of 2000...so I recently installed a donated HI-4E (external not in the cone). I run a S&S shorty E carb, with a 24 tooth front drive sprocket...so the lack of detonation coming from a stop, to me, made a huge difference.

Good luck with your decision.