Autolite 2100 ideal venturi size for built 289?

Hi guys, I’m debating my options to replace the leaky reman carb on my engine. It’s my original 1968 C-code 289-2v (actually ended up being a 302 block with 289 heads) which has been fully rebuilt - bored .030" over, balanced, decked, slightly upgraded cam, valve job, etc. Still rocking the stock 2V intake and heads.

Being that it’s a bit healthier than stock, it seems to me like it could handle more CFM than the stock 1.08 venturi carb would provide. The way I see it, these are my options (starting with stock):

1.08 Venturi(287 CFM) 289 Windsor, 302 Windsor
1.14 Venturi(300 CFM) 289 Windsor, 312 Y Block, 332, 352, 360 FE
1.21 Venturi(351 CFM) 351 Windsor
1.23 Venturi(356 CFM) 352, 360, 390 FE, 383 MEL

Would 1.23 be too much? There is a good core one here that I could rebuild and test out. Was also thinking that 1.14 might be a good middle ground, but don’t know if I’d be selling myself short.

Opinions welcome!

.98 = 190cfm
1.01 = 245
1.02 = 240
1.08 = 287
1.14 = 300
1.21 = 351
1.23 = 356
1.33 = 424

The 1.23 should be fine for a 289 with a little extra pep. There are plenty of people that are running a 600 4 barrel on a 289 or 302.

There probably won’t be a difference that you feel in seat of the pants. But, it might be a little quicker in the 1/4 mile.

Many years ago, my brother and I replaced the stock 2100 on the 302 in his mid-'80s pickup with a larger 2100 from a 1970-ish 351. Engine was stock except single exhaust was converted to duals, and timing was bumped a few degrees. It didn’t turn the truck into a hotrod or anything, but there was a modest, but noticeable, improvement in power when passing or merging onto the highway. He also noted less of a tendency for the transmission to drop out of high gear when climbing hills or pulling a trailer. No driveability problems and mileage wasn’t noticeably affected. I wouldn’t hesitate to use the biggest 2100 I could get my hands on (or even a 500 cfm Holley 2-barrel) with your setup.

Thanks for the input! I went ahead and dismantled / cleaned / rebuilt the 1.23 carb (which is an original '68 piece with the Autolite tag) and slapped it on the car last night. Initial impression: kitty like! Seems to run smoother than it did with the leaky reman 1.08, and more responsive - no hesitation. Just need to lower the idle and make sure the mixture is right. I think this was a good choice. :laughing:

Yeah dude, use the biggest ones you can find. Pay attention to the jetting now though. Read your plugs and whatnot.