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RB34 big cam idle issues.

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A while since my last post, built an RB34 stroker motor and went for the JUN 11mm lift 288 degree cams spec.

Now the cam is not big in my old Alfa 3.0 engine builds, in the 3.4 liter RB engine its massive !

Really battling to get good, consistent  idle and some meaningful vacuum .

I'm currently playing with cam LSA and LCA`s and with big timing figures(45deg) I can achieve a reasonable idle but its not consistent.

Main input is MAP based.

Any ideas from the big cam blokes here ??


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One possible solution here is to do a setup like this:

Equation Load Source = 'Load=BAP/MAP Xover'

Fuel table 1 load (Y) axis = 'TP(Main)'

4D Fuel table (on all the time) load axis = 'MGP'


You would have the load axis of the 4D table start just below atmospheric pressure (0 kPa MGP), have this first row set to zero. When the engine is idling it would be using values from the main fuel table, which is based on TP(Main), so should be pretty stable.


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