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Tuning help Holley Sniper

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Hey guys, was looking to get some base line info. 

What would be ideal for idle timing and AFR at idle, cruise and WOT. Looking for timing specs for all 3 also.

I'm using the full hyperspark ignition which adjusts timing and I confirmed I have 15° after setting the static to such. I believe after that all I have to do is disable static timing. Pretty sure it still wants an initial timing number to attempt to maintain though. 

So with that what are some good target numbers based on my engine.

408c. 10:1 cam is 224/232 @.050. Hyperspark ignition. I have no vacuum numbers to go off of. 



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I don't have EFI, all carbs, but the numbers should be the same. Scroll to the bottom of this article for general numbers. https://www.enginelabs.com/news/video-understanding-your-wideband-o2-sensor/

Depending how much overlap the cam has may make idle reading unreliable. Make sure the engine is at operating temps before you take any readings. Generally speaking, if you get the cruise reading right the idle will right or close to it. When you do a WOT pass start in high gear (1:1) roll into it slowly to minimize "accelerator pump" enrichment. My current numbers for 408C, 4V, BIG cam, 750 DP, are; Idle in drive @ 1050 RPM 14.0, light throttle, level cruise 14.8, WOT 13.2. Good luck with the tuning. Chuck

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This is from the sniper manual. I have the MSD Atomic and its pretty much a self learning device. Each engine will act a little different. Make small adjustments and keep records of changes. If I remember correctly the higher the number the leaner it gets.



Idle Air/Fuel Ratio – Typically between 13.5 and 15.0. Engines with larger cams may need a richer setting for smoothest idle.

Cruise Air/Fuel Ratio – Typically between 13.5 and 15.5. Engines with larger cams may need a richer setting for smoothest operation.

Wide Open Throttle Air/Fuel Ratio (WOT) – Typically between 12.0 and 13.0. Running richer may reduce power. Running leaner may reduce power or cause potential engine damage.

NOTE: The Target Air/Fuel setting between IDLE, CRUISE, and WOT is blended together automatically. Consequently, the air/fuel you see on the MONITOR screen, may not be exactly what you set for the settings. Changing these settings raises or lowers the “curve” of that specific area.

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73'Mach 1, Tnfastbk and c9zx offer sound advise, I would only add that Holley states that one should start their tune with the spark advance feature turned off and work off of your existing distributor advance curves.

also get your IAC really dialed in , If you don't have air conditioning shut the ac kick feature OFF. it will help you dial in the IAC easier.-

when you have your air/fuel FULLY dialed in and your learn tables are are almost ZERO then would be the time to let the sniper handle your ignition advance.

I have installed a few of these systems on friends cars and found that there are 3 different levels of tuning, if you allow the system to only self learn, you will probably be disappointed.

Don't tune by numbers, tune by what YOUR engine likes and what it does NOT like.


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Before going to EFI you probably had a mechanic curve on the dizzy. If that was working good build a timing table from those settings.

Drive around and take some datalogs. Listen to the engine, and combined with info from datalog etc tune the engine.

Don´t forget to look at the spark plugs, even with EFI its a good check.

For knowing your limit you have to pass it ::thumb::


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