Well I have a decision to make and I'm pretty lost. In the very near future I am purchasing my carb setup and I want something that gives me the flexibilty to keep up with mild to moderate upgrades. So far I've narrowed this down to either dual 40mm DCOEs or R1s.

Currently my engine is an A15 with an H89 head, no porting or milling yet and the stock cam. Prior to start up I plan to unshroud the valves, install dual valve springs (and the required retainers), light weight pushrods, replace all of the other valvetrain parts and regrind the cam to make power to 7000rpms. I'll also run new extractors and a 2" exhaust to prepare for future modifications. All I'm looking for is a carb setup that can handle all of this and possible more down the road.

R1s are the cheaper option, so can R1 carbs flow as much as 40mm DCOEs?
I have seen R1s referenced for boost, is this easily achieved with DCOEs?
How difficult would you say tuning either setup is if you have a wideband O2 and basic understanding of carburetors?

I'm sorry if these questions seem dumb, but I am still doing research and I want to make this choice once and not regret it later. If you have any personal experience with either or both setups please feel free to share. Thanks

-Jacob

40mm should flow the same as all but the only way a weber 40mm can allow the same air as the 40mm bike carbs is by having nothing in the way like chokes.

The bike carbs are also shorter where the air runs through them while the webers are straight for almost double the length.

Bike carbs like the R1s are very popular worldwide and most carbie savvy folk will be able to tune them or get them right to your needs. However best have all the other things ready installed before you tune them or they like most performance carbs will need to tuned again.

also chat/PM to the youtube peeps that have samples up, Phillipines are crazy on them or find a carby place or motorbike mechanic that knows his stuff

Another choice for wild to mild is Weber dgv. Racers turning 8000 rpm and 160hp. The dcoes or r1s can be smoother at part throttle and definitely look cooler.

I like the weber dgv on my 620, but the a-series looks much better with sidedrafts. My car will never be a racer. I just want it quick and pretty for shows and fun to drive for joy rides. The sidedrafts sound so much better too.

Right now I'm imagining what bike carbs would sound like screaming to 9000rpms. I might scare away all the honda 250 guys :P

So far the huge plus I see is the ability of the R1s to handle mild boost easily. I only plan to run 5-7psi on a supercharger but this will be way down the road. However, if I can make an investment in my carbs now that will handle the boost and only need a different tune, that saves me money over all.

Dcoe handles a low 10 lbs boost easily too.

I did not know that. Thats why I'm asking all of thise because I really don't know what either setup can handle.

So far I have R1 pros as lighter, better flowing, easy to boost reference, and due to my location, easier to find a tuner (lots of bike shops), and overall price is about $400 cheaper unless I make my own manifold. The biggest con is there is a lot less info out there for our engines compared to DCOEs.

40mm DCOEs: Very reputable, plenty of parts and good tuning guides/material out there, can handle 10psi (does this require a box or different seals?), and brand new carbs. The biggest cons are finding a manifold for a decent price, cost of the entire setup compared to R1s, and lack of local tuners.

I will be going the r1 carb route my self i have just put in a cam and ported then head and the port are alot bigger than the stock manifold holes and they cant be ported to the same size as their just to thin to port that far

so im planning to get a flange cut to match the port size and make my manifold from stainless steel most likely as i dont have a tig to weld alloy

i got a few quotes for the r1 carbs from bike wreckers they all want close to $300 which is quite abit but still alot cheaper than dual dcoes i think

I dont think it takes to much to tune r1 carbs there jets are interchangeable with dgv webers just changing the main jets to like a 1.60mm gets it in the ball park then its fine tuning

theres good info on this forum http://community.ratsun.net/topic/7862-r1-carbs-lots-of-pics/

R1 carbs are halve the price of italian webers and 60-70 percent of italian dellortos which also have limited parts availability for tuning as they are no longer supported last I heard form our carb specialist place "canterbury carburettors" - some places still have parts for them but do you really want to go quad carbs then turbo them? its quite a challenge.

If you get them from the states you get them cheaper but then postage adds to them.

I bought some 48mm carbs for $300 landed and are lighter shorter than 48mm webers, allowing more room in my bay but no way on earth would I run boost through a carb or four of the buggers. Too many issues with tuning, different weather/temps, diff fuel quality at different pumps, diff atmospheric/altitude conditions etc.

A simple SU or Stromberg carb before your supercharger with a little h20 is much easier- go straight to supercharging and single carb dont bother with NA and dont expect 9000rpm unless you have deep pockets and careful planning.
Boost does not need big rpm especially supercharging.

Yeah I wouldn't be running boost theough them, I'd be more inclined to go with a weber manifold and an efi kit that fits the manifold then run boost through that setup.

For the low amount of boost I'm planning efi isn't really needed. Not shooting for anything super fast :P