everyone seems to choose the side draught carbs dcoe style. are the down draught carbs much different? I have been toying with the idea of using carbs for a while and looking at some of the down draught carbs on the net, they are a different solution on the 8v engine. will they fit?
if you can get/make a manifold, however the mixture needs to make a 90 degree turn so not ideal, find them on maestro gti thingies, some aircooled porsches and tuned beetles, weber versions are IDA instead of dcoe rebuild guide however for all the benefit the carbs would offer, megasquirt would be easier i reckon
...and alfasuds and earlier Alfa 33's On a boxer engine you don't get the 90 degree bend, so a better design for them.
there are two main downdraugtht weber carbs i thought,... the IDA and the DCNF. both totally different carbs but essentially both work pretty much the same as the DCOE's I think. However, I thought the MG meastro's used the DCNF type not the IDA/IDF type. not sure completely sure though! (used to know all this stuff once upon a time!) however, to answer your question, i think the best type depends on your engine layout. generally on a boxer they are better because they form a nice direct straight inlet, however, with an inline 4 dcoe's are usually best for this same reason. its not quite so straight forward with the vw 8v though because its not a x flow. the dcoe gives the best inlet geometry but the down draughts have the advantage of a better cooler air supply (because of the exhaust), so its difficult to say. unfortunately I have not tried either so im no expert (although i am drunk)
downdrafts would need a custom manifold making, but dcoes would do better with a crossflow head. $$$$ either way
