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Thread: Stock 427 BBC start fuel settings.

  1. #1

    Default Stock 427 BBC start fuel settings.

    Hello. Anyone running Holley EFI Sniper on a stock 427 BBC? Having some hot starting issues and stumbling/stalling after some seconds when started cold and not working the throttle. What would be typical ballpark settings for Cranking Fuel, After Start Fuel and Coolant Enrichment as a reference?

  2. #2

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    These are things you have to experiment with and try for yourself. No one can give you exact numbers. They all vary from combo to combo.I have a large cube small block and this is what worked for me. Now when you have hard time starting try holding throttle partly open while cranking, if this helps you can do one of two things. 1 Reduce cranking fuel and or fuel prime. 2 increase IAC startup position for the temps you have trouble. Typically these two things get your starting consistency dialed.

  3. #3

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    @Stale67ss: Cranking Fuel should be roughly the same as hot idle fuel. Pro tip for Sniper tuning is to sort out the hot idle first. Get the engine up to temp at a steady idle. Work on the Target AFR and timing until you have a nice stable hot idle. Adjust the throttle blades to get the IAC setting correct. Datalog your hot idle so you have a record of the sensor readings. Pay careful attention to things like the MAP, IAC, Fuel Flow, RPM, etc., so you know where on the maps everything is.

    Once you have hot idle dialed in then you can work on hot starts. Once you get hot start dialed in you can work on cold start. Then work on off idle, then cruise and then WOT. Last thing to work on is usually the AE stuff. Most of the time you don't need to make any AE adjustments once all the base tables are dialed in.

  4. #4

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    Good tips there! Andrew
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  5. #5
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    http://forums.holley.com/showthread....7913#post77913 (Related Cranking/Startup Tuning Post)
    https://forums.holley.com/showthread...894#post219894 (Good Startup Tuning Advice Post)
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  6. #6

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    Quote Originally Posted by Stale67ss View Post
    Hello. Anyone running Holley EFI Sniper on a stock 427 BBC? Having some hot starting issues and stumbling/stalling after some seconds when started cold and not working the throttle. What would be typical ballpark settings for Cranking Fuel, After Start Fuel and Coolant Enrichment as a reference?
    A ballpark setting for Cranking Fuel would be 7 lbs/hr. But that's just a guess from experience. The correct answer is to use the hot idle number once you have a nice stable hot idle.

  7. #7

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    Thanks for the tips and links. In general, the tables where way too rich. So leaning out Cranking Fuel, After Start and Coolant Temp Enrichment solved all the issues.

  8. #8

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    Yes, Holley programs the Sniper rich just like they used to calibrate their carbs. They love the smell of raw gas in the morning.
    The Sniper tables get super rich if you pick the race cam. I've tuned a lot of race engines, but I've never used the race cam setting since it's way too rich for even a full race engine.

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