Hello Nofrills. I have a '65 230S W111 with identical carburettors as your W114 & I've taken mine off several times now using an ordinary 12/13mm open ended spanner after I've removed the valve cover. It's very tedious work & you just have to be patient when unscrewing the nuts with your fingers once you've loosened them. I never even considered loosening the manifolds to get access to the flange nuts. Screwing them back on again is a bit of a pain, but once again, patience & smallish fingers helps here.