More questions.. About timing this time

Propane, Butane, LPG, GPL, C3H8, C4H10
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Joined: Sat Jan 15, 2011 5:21 pm
Location: Fsj BC

More questions.. About timing this time

Post by dent » Tue Apr 19, 2011 11:24 pm

I'm running a computer programmable distributed with boost retard function on my turbo small block, the problem is the vacuum signal for the distributed is usually taken off an impco 425 on the port before the throttle plate. Since there is going to be some restriction (and hence a pressure differential) due to the throttle plate I've been taking distributer vacuum/boost signal from after the throttle in order to have a more accurate boost reading. The problem Is when I shift hard the distributer almost instantly swings from retarding the timing under boost to full vacuum advance, causing a "hiccup". By minimizing the timing difference between the two i have been able to minimize the problem but it us still an issue. Anyone have experience with this? I would just like to arm myself with a bit of theory and insight from those with more experience before I continue recklessly experimenting with my project. Am I better off using the 425 "ign" port and adjusting the boost retard map to the slightly higher pre throttle plate boost pressures?

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