If you are going to do it the 'going out of tune' part of the problem will be down to one thing - the quality/strength/alignment of the linkages. If there is _any_ flex in them at all, you will be in the barbed wire canoe without a paddle etc. It's important enough that I'd _seriously_ rather put a 2 barrel holley on there (for argument's sake) than quad carbs without great linkages.

Now for the really shady part - some of the commercially available linkages are also some of the flimsiest. You'd generally want to talk to circuit racers and see what they run, as driveability/consistency coming out of a corner is what wins or loses the race for the most part.

One carb per cylinder definitely has the best throttle response of all, and the widest powerband (and theoretically has slightly less peak power than a big single carb with a large enough plenum - and on that front, I don't believe there is any off the shelf manifold for an a-series with such a plenum and adequately sized/shaped runners, so the multi-carbs really are 'it' as far as performance goes)

You may find, that by the time you get a set of motorbike carbs dialled in with the right needle/jet and other circuits (if they have them, not all do much beyond that) you will have spent a decent chunk of money and time, and the 'tried and true' twin webers would have been the same price. Weber bits are still fairly easy to come by, but for quad bike carbs if you have to experiment with needles, it's 4 at a time, and you'll likely not get it right the first (or even the 3rd or 4th) time. It can get expensive really quick.

At one point in time (roughly 40 years ago) the 'go' for all out minis (sorry for mentioning the enemy!) was an 8 port head with 4 motorbike carbs (amals). they definitely had an edge on a racetrack, but below the cam's sweet spot rpm range, they were far less driveable, stunk of seeping fuel (that was practically impossible to stop due to 'standoff' where you get a fog of fuel puffed back and out the intake trumpets at certain rpms).

I'm certainly not against this in theory, but you'd _really_ want to chose whatever bike carbs meet the criteria - a. enough flow b. tunability of all circuits with relative ease and c. cheap and widely available tuning parts to make the job doable at all, and you'd _definitely_ want to invest in a wideband ego sensor and spend the time logging it. GEtting peak power on a dyno is all fine and dandy, but getting the driveability right across the entire rpm spread can take some considerable time, and is frankly best done on the road, as you can never simulate it all on a dyno (and it would cost more than efi (i.e. parts costs to start with efi, which then allows you to trim the fuel electronically, no more parts to source and install) to do it on a dyno)

This may sound like I'm anti- carb - I'll state for the record nothing I own has or likely will be efi for the forseeable future - I'm 'into' carbs, but have to be honest about what you are facing.

Having said all that, if you knuckle down and see it through to successful completion, you'll have a great result, and probably one of the best sounding a-series out there.

Yeh man cheers for the info want to learn as much as i can. I do want the car quite driveable as well and dont want to muck around to too much extent in making up custom parts etc. have found a mechanic to assist in the build so will discuss with him in what he thinks etc. but any info is greatly appreciated

cheers

There is alot of work ivolved in making them work properly. You will need to make a manifold,cable system wich is critical for even throttle opening. The fuel set up is very hard to get right because motorbike carbs are gravity fed so you will need to feed fuel out the main tank into another tank simalar to a surge trank you see on efi set ups. But that will have to gravity feed the bike carbs. I have heard that they work very well in off road set ups ie buggy racing. You will probably need 4 carbs off a 350cc dirt bike. Makuni are good but very expensive for new ones. I use twin 40mm webers & would recomend them to any one because when in good condition they are very tunable. People will bag them out but go to any historic race meet & look at what guys there use & that will give you some ideas on what carburation to use.
I hope this info helps

Coops

hey i will be hopefully building an a14 soon to put in my 120y. i have read a bit about putting quad motorbike carbs on and like the idea. what would be best to use on a A14 and are they a pain to keep in tune etc. what are peoples ideas an thoughts on this setup?

any help is greatly appreciated

cheers