Need Engine Timing Clarification (Holley Sniper) (1 Viewer)

[midknightc3]

Trying to get things straight in my head, but with the necessary information in many different threads I quickly get my lysdexic brain turned around. Some back story, my engine has been rebuilt once (that I know of), and a head job after that. This means (I'm pretty certain) the head has been shaved twice. She's fully de-smogged with a Holley Sniper 2000, JT Outfitters header, and re-curved large cap dizzy. As I accelerate, she looses significant power. This makes me think something is happening with the timing advance as I accelerate. Now for my confusion:

#1 - I can't rotate the dizzy past 13* BTDC. It hits a hard stop and that's the end of that. Is this normal, or am I off by a tooth? If I'm off by a tooth, which way do I need to rotate the dizzy gears to fix this? Looking down from the top of the dizzy, clockwise or counterclockwise?

#2 - If it won't rotate past 13* BTDC, does this also mean the vacuum advance hits a stop and can't advance any further? Seems to me this would explain the increasing loss of power as RPM's increase?

#3 - I'm after 13* because I live at 5,500', which I figure is full actuation of the old HAC, = 13* (I don't have an HAC, just trying to match the timing, Sniper matches the AFR). With the Holley Sniper, does this hold true?

#4 - Watching the timing light, as the RPM's increase, the light is firing closer to the TDC marking, not farther away, is this how it's supposed to work? I definitely thought it was supposed to go the other direction...

Sorry for the list of question in one post, but trying to consolidate my confusion into once place.

Thanks!
Clark

 

[fjc-man]

The outer chamber on the vacuum advance unit is actuated by the HAC unit which if functional is good for 6 degrees of advance. The inner chamber when actuated by throttle position vacuum is good for 16 degrees of advance. The centrifugal advance (mechanical) is good for approximately 10 - 12 degrees of advance.

 

[Pighead]

The dizzy hold-down limits it's rotation. I H8 that. You have to remove the hold-down bolt, pull the dizzy up an inch or so so that you can turn the rotor. Move your rotor Counterclockwise to advance timing.

Edit: no, wait. The normal direction of rotation is clockwise right? So moving the rotor clockwise advances timing...

 

[midknightc3]

Counter clockwise increases the timing advance. I can only rotate mine to exactly 13*, but I have only loosened the hold down, not removed it. I'll remove it this weekend and see what happens. That said, I don't think I need more than 13* as my base (maybe less?), but would this same stop also stop the RPM/vacuum related advance? I have a single port vac advance and have re-sprung the dizzy to match the desmog.

 

[Pighead]

Turning the body of the dizzy Counterclockwise advances timing. Therefore, turning the rotor clockwise does the same.
I am running a bit more than 13*BTDC and like it.
I got a single diaphragm advance unit and have been fiddling with springs too. What springs did you use?

 

[midknightc3]

The thread I followed said to use the silver springs for both, so that's what I used.

Builds - The Rushing Turdle

Looks really good! I'd be worried about the extra leverage that the rack has on the mounting brackets since the weight won't be directly on top of them. I'm not an engineer, but I would think your weight capacity will decrease because of that.

forum.ih8mud.com

Seems to work pretty well. One caveat with my thoughts on performance that I realized recently, I'v never drove or even rode in another 60, so I have absolutely nothing to compare to.

Clark

 

[BlackCat]

If you can’t get it past 13 you’re probably a tooth off. What are your AFR’s when it loses power? Mine used to randomly fall on its face while learning, I’m ashamed to admit it but I had the wrong model sniper programmed in when i did my initial setup. It ran, but it did some weird shiznit.

 

[fjc-man]

Turning the body of the dizzy Counterclockwise advances timing. Therefore, turning the rotor clockwise does the same.
I am running a bit more than 13*BTDC and like it.
I got a single diaphragm advance unit and have been fiddling with springs too. What springs did you use?

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Pighead, how many degrees of advance is the single diaphragm unit good for? Is it threaded / adjustable?

 

[Pighead]

Pighead, how many degrees of advance is the single diaphragm unit good for? Is it threaded / adjustable?

Dunno how many degrees. Got it from @4Cruisers , he sent a graph with it which i can't read. It is threaded with 2 locking nuts and seems adjustable.

 

[4Cruisers]

Pighead, how many degrees of advance is the single diaphragm unit good for? Is it threaded / adjustable?

I set the advancer to limit the advance to ~10 distributor degrees (~3.8mm maximum travel of the actuator rod).

 

[midknightc3]

@BlackCat My AFR's are usually right around mid 13%, doesn't even seem to change even when I loose power. I will definitely go back and check my programing, putting in the wrong model sound like exactly the sort of thing I might do when setting things up, and weird shiznit kinda matches my thoughts on what happens...