The 350 TBI flows 500 CFM @ 3" HG (the old 2 bbl rating). I think the throttle bores are 1 5/8" to 1 3/4" each - but I don't have one here to measure. The 454 ones are 2".
51 GMC 4.2 turbo Can't solved today's problems using the same technology/thinking that created them
