Anybody use Performer 289 and Autolite 4100 ?

You'll need a thick gasket as the 4100s don't like to seal to alum. intakes without a little help, but that should do it. 4100s are great carbs

Oh, and Pony Carbs is a bunch of incompent morons, IMO. Many horror stories about crap left inside from their rebuilds. I've heard it said that their timing by ear method is a way to mask imperfections in their rebuilds and after what I've seen and heard over the past few years, I'm inclined to belive it. Not that timing by ear is that great of a thing to be doing anyway...

Better luck with Pony Carbs

I bought a rebuilt 600cfm 4100 from Pony carbs, and with no adjustments other than slightly upping the idle, I bolted it onto my mildly warmed over 351W which at the time had a performer 351W intake, Duraspark dist, 1 5/8" headers, a Tremec 5 speed, and 3.70s with a trac lock in my 9" and drove from Southern Maryland up to Washington D.C. and down across the eastern half of the U.S. to Dallas, Texas with not a single problem. On the freeway I got 23 mpg cruising at 70mph!! In town it dropped significantly to around 15 or 16mpg, but it started like a modern EFI car. The only shortcomings I believe the 4100 has are 1) biggest size available is 600 (would love it in a 750 for my 408 stroker) and 2) it doesn't like dirt at all. If you keep a clean filter you can avoid that problem.

As far as timing by ear goes, if you have a mild performance or stock rebuild, I can set the timing by ear and get good performance and mileage, because there is a range of about 4 or 5 degrees that doesn't seem to make much difference in performance or mileage, so it can work just fine. If you've invested in big heads, radical cam, high rise intake, stroker kit etc. there can be a noticeable improvement with only a few degrees difference.