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Re: Jetting Twin Dellorto's DRLA in A15

Subject: Re: Jetting Twin Dellorto's DRLA in A15
by ddgonzal on 2017/2/17 22:25:17

That's the easy part. For ballpark correct A/F ratio:
* main jet is 4x venturi size = 132
* air jet is main jet + 50 = 182

Now for the hard part: transitions ... when the throttle changes, how much fuel it requires it differs with different engines and camshafts. These seem like a good starting point:
* Emulsion Tube: 7772.6
* Idle Jet: 40; air bleed: 7850.1

To be "safe" means make sure the A/F ratio never goes lean (lean = above 14.7:1). That means starting rich, later when you tune the carburetor you'll lean it down to best performance. Best full-throttle power: 12.5:1 ratio. Best cruise: 14:1. Best economy @ level cruise: around 15:1