Best Fuel Pump Advice for Newb...

7milesout said

The only strange thing is that now at WOT, I'm now seeing a steady 13.2 AFR. Before it was at 12.2 AFR, which is rich best torque. So, I'm going to go to my handy - dandy spreadsheet to determine the size needed for the secondary main to bring it back to 12.2. Can't see why a fuel pump would have any bearing on WOT AFR. Maybe it's got to do with the fuel, I don't know. But it needs more fuel at WOT for sure. 13.2 is safe, but optimal H.P. is achieved at 12.2 (at least that's what I've learned).

Click to expand...

It's possible the pumps have enough difference in the return spring the fuel level is now a little lower. Even so, that usually a fine trimming - nothing near a full AFR ratio - and would impact low throttle the same or maybe even more. Maybe something to do with whatever was wrong with the old pump. All speculation anyway.

As far as adjusting the main jets; if it needs richer, it needs richer on all four corners
if it was dialled in, with the prim/secondary jetting as you had it. If it was dialed in, I'd just go one size larger on all four and see if mph increases.
If it wasn't dialled in that close, then SOP would be 2 jets sizes up on either the primary or secondary and see if mph increases.
Then check the spark plugs to be sure WBO2 meter isn't misinterpreting what's going on.