I've got a 780cfm on my 289... 800 on a 351 should be fine.

As the other said, you might run into driveability issues... and you might not, it just depends on the tune of the carb. You will most likely loose some mileage though, because most of the time the Holleys are rich on the idle and transition circuit, which is what you will be running on most of the time with an 800 on a mostly stock 351. I think they calibrate them rich because most engines will DRIVE just fine rich, no hesitation or surging... they'll just get crap for economy... but if they're lean, you can run into all sorts of driveability issues.

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'86 Bronco, 460, E4OD; '85 Ranger, 350hp 289, T5, 12.9@110.5
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