1 3/4" carbs on 1800 B series

[paul]

Has anyone any experience of fitting 1 3/4" twin carbs to an 1800 B series? I have been told that this conversion is OK for the racing boys but it causes a lumpy tick-over, loss of bottom end grunt and high fuel consumption. Is this correct? Has anyone done this conversion an been happy/unhappy with the result?

[lil_red_roadster]

Re: 1 3/4" carbs on 1800 B series

Paul, I strongly recommend Peter Burgess's book, Power Tuning the MGB...amongst lots of interesting info (all empirically derived) are a range of 'power recipes' consisting of head mods, exhaust and various other changes. Any move to bigger carbs needs to be a part of a holistic approach to tuning, looking at the filters, cam choice, exhaust and manifolding, your overall objectives, not to mention what carbs to choose and so on. It's quite surprising how effective the standard carbs are when properly set up. On an otherwise standard engine larger SU's may well be more trouble than they are worth...

Personally I tried adding a pair of standard 1.5" SU to my SC roadster and found the slight gains were not really worth the added effort of trying to keep the damn things in tune...not to mention the hassle of chopping down the spacers just to fit thin and inefficient pancake filters!!

Still, sometimes the fun is in the effort... ;-)

[paul]

Re: 1 3/4" carbs on 1800 B series

Thanks for the feedback Jez. I am not so much interested in the increased performance but have acquired a brand new old stock set of carbs from an 1800s landcrab. My quandry is, do I make them secondhand by fitting them (losing the 'new' value)and be disapointed with the result or, sell them and invest in reconditioning a set of 1 1/2" carbs.