Adjusting for weather

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by rb0804, Oct 14, 2017.

  1. rb0804

    rb0804 Member

    Aug 7, 2010
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    how do you guys adjust for weather? Put the info in the Davenport software and change the main jet, change the pump loop, or do it with a timer? Do you also change the barrel valve so you have the same fuel flow every time at stage or do you "let it ride" and it is what it is with the main jet change? What happens if the weather gets real good and the Davenport says put in a blank? Will the car start idle and stage like normal?
  2. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Mar 10, 2004
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    Lots of questions. Do not do it with a timer. The pump loop is an extension of the main jet. It is parallel so what I like to do is keep the mainjet within a certain size range let’s say 70-100 so the percent of fuel change remains close tothe same with a jet change. I do this by adjusting the pump loop jet size until the program puts the main jet where I want it. This is easy to do in the Jetsize software. As far as the barrel valve leakdown I let it ride. The idle has nothing to do with the run but can pollute the oil if too rich. So if the oil is ok then leave it alone. If Jetsize wants a blank the you really don’t know where you are so adjust or blank off the pump loop until you get a main jet size in the program. The main jet size has no effect on idle but can change your stage.
    noslin likes this.

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