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grimm862
02-05-2007, 12:07 PM
I did a search on this and didnt get much info. I read that its hard because of the break booster. But what else is there to know. I would really like to do this to the eta.

Turbo-Brown
02-05-2007, 01:14 PM
Why use carbs when throttle bodies do the same job so much better?

I've seen a couple of manifolds for the M20 which take DCOE style bodies/carbs.

One type pointed the inlets straight at the brake booster like you've mentioned, the other pointed them straight up at the underside of the bonnet which isn't really ideal either.

There's plenty of room if you have the TBs mounted on a gently curving manifold though (needs compact TBs though) which would let you mount a plenum which can be fed with fresh and importantly filtered air.

grimm862
02-05-2007, 01:29 PM
carbs get rid of the electronics for the fuel and idle. ANd i have problems with that. It would be real nice and not to many people do it. So it will be different.

Is there any links or write ups or anything?

eurotrashe30
02-05-2007, 02:04 PM
i imagine that side drafts would give a better throttle response than our single throttle body. plus no electronics would be nice.

dp2275
02-05-2007, 02:48 PM
sidedrafts are the shit for oldschool rides. only downfall is if you plan on driving winter and summer, think again unless youve become a pro at jetting and adjusting them :wink:

i had a sidedraft manifold for my 16v gti, and i know there is a company that makes similar ones for the m20(not sure who), but ive seen used ones go for $400 so it wont be cheap.

you should look at cost before doing this also....priced a set of DCOE's lately? 400-900 for a set(3) of USED carbs in ok condition. not cheap! you also have to synchronize them unless you find a trio of matched units ($$$). if you are willing to spend the money, ill be the first to tell you to do it :D mad style points!


EDIT: forgot to mention...if you go sidedrafts, you better pick up a hot cam and do some headwork too, otherwise you wont see the full potential of them :twisted:

grimm862
02-05-2007, 03:03 PM
sidedrafts are the shit for oldschool rides. only downfall is if you plan on driving winter and summer, think again unless youve become a pro at jetting and adjusting them :wink:

i had a sidedraft manifold for my 16v gti, and i know there is a company that makes similar ones for the m20(not sure who), but ive seen used ones go for $400 so it wont be cheap.

you should look at cost before doing this also....priced a set of DCOE's lately? 400-900 for a set(3) of USED carbs in ok condition. not cheap! you also have to synchronize them unless you find a trio of matched units ($$$). if you are willing to spend the money, ill be the first to tell you to do it :D mad style points!


EDIT: forgot to mention...if you go sidedrafts, you better pick up a hot cam and do some headwork too, otherwise you wont see the full potential of them :twisted:
The weather down here is not an issue.

But all of that other stuff you said may be.

Theres no cheaper way i could go about this?

ID really like to do this. So i think im going to keep looking into possible setups.

THis is why id really like a old vw bug. or a carbed bmw =P~

dp2275
02-05-2007, 03:30 PM
i really doubt youll be able to find a trio of carbs for under 400 that dont need a buttload of work. on top of the carbs, you still need the manifold and velocity stacks or filters. both of which can be expensive.

if you really have your heart set on this method, id pick up the peices one at a time to lessen the blow to your wallet. im pretty sure i saw jon volk sniffin around a sidedraft manifold that was for sale on another board, so maybe PM him and see what he knows 8-[

backtrail69
02-05-2007, 03:51 PM
I have a single 45dcoe on a cross flow intake on my 2002. It works great, but you have to tune it all the time to keep up with the weather changes. It starts RIGHT up faster than a EFI car when its tuned right. Throttle response is amazing.

grimm862
02-05-2007, 03:59 PM
you guys live up north temps dont vary much at all down here. Its hot as fuck in the summer EVERYDAY, and is warm in the winter. There is no way i could make a custom manifold and run only like 2 carbs?

backtrail69
02-05-2007, 04:39 PM
you guys live up north temps dont vary much at all down here. Its hot as fuck in the summer EVERYDAY, and is warm in the winter. There is no way i could make a custom manifold and run only like 2 carbs?

You could, but there would be really no point it would be like..ALMOST ITBS.

Turbo-Brown
02-05-2007, 04:57 PM
There is absolutely NO WAY to run four chokes on a six cylinder eninge! You'd end up with probably the outer two cylinders running properly and the middle four with all sorts of problems.

Seriously, TBs are just so much better in every way than carbs. With carbs you've pretty much always got some form of compromise with your fuelling. Apparently people used to blame their cams for shite idling and low speed running whereas the problems were actually caused by the carbs.

With TBs, you can have exactly the right amount of fuel for any given speed/load combination, plus you get razor sharp throttle response, plus you get decent fuel economy, plus you can tame all but the wildest cams for road use, plus you can get through emissions, plus you can use FI with them easily.

There are no advantages to carbs over TBs.

grimm862
02-05-2007, 05:04 PM
There is absolutely NO WAY to run four chokes on a six cylinder eninge! You'd end up with probably the outer two cylinders running properly and the middle four with all sorts of problems.

Seriously, TBs are just so much better in every way than carbs. With carbs you've pretty much always got some form of compromise with your fuelling. Apparently people used to blame their cams for shite idling and low speed running whereas the problems were actually caused by the carbs.

With TBs, you can have exactly the right amount of fuel for any given speed/load combination, plus you get razor sharp throttle response, plus you get decent fuel economy, plus you can tame all but the wildest cams for road use, plus you can get through emissions, plus you can use FI with them easily.

There are no advantages to carbs over TBs.
Well i think for the less electrically inclined they are better then electronic fuel injection. Im decent with electronics however.

Im just tired of my shady ass eta wiring harness thats fucked beyond repair. I got coolant sensors that arnt soposed to be there ( i think) ANd i really dont know what to do with it. I wish someone could help me with this shit.

Turbo-Brown
02-05-2007, 05:32 PM
You can make up a new loom in a day for an aftermarket ECU as long as you can follow a simple wiring diagram, buy an MS, junk the original ECU and it's loom and that's that sorted.

Setting up carbs is an art form in it's self and it's dying out for good reason.

You map an engine by trial and error. Tap in a little too much fuel, tap out a tiny bit, great! Got it right! Move on to the next site.

With carbs you have to disassemble the bloody things to change the crude mechanical bits inside, then restart the engine, get back to the engine speed / load in question and see what effect your change has made. Move on to high load fueling and find it's running lean. Swap out a jet or something, try again. That's not too bad, but now it's running rough in the mid-range and there's not much you can do about it.

Work on your progression, not getting the right fueling on a light throttle? OK, either file a little bit off the butterfly if the fueling's not quite right or if it's really dire, drill a new progression hole. Oh piss, too far with the filing or hole in the wrong place. That's one knackered and potentially expensive component.

I can see why people would think carbs to be the easy option, but to set them up isn't easy and to set them up properly so that you get a clean pull across the entire gambit of engine speed and throttle opening is apparently nigh-on impossible.

With TBs, all that goes away!

Obviously it's not my choice, but from what I've seen, TBs make so much more sense than carbs!

Out of interest, do you need to run a cat where you live? If so you don't stand much chance of it living long with carbs :(

grimm862
02-05-2007, 09:44 PM
No tests to pass down here thats one nice thing.

smooth
02-06-2007, 04:44 AM
Turbo-Brown sounds like he's had to deal with carbs before...as have I.
Used to build mopar in the early days and I agree with every single thing he wrote.

I can't think of a single thing nicer about carbs over TB's other than polished chrome :D

funny how that works, we used to dream of ways to fit electronics to our early v8's. hmm, do away with electronics? I'm guessing you never had to gap your points!

it's bearable with a hemi, but after my datsun with a weber carb (fun as hell to toy with, I'll admit) I vowed to only go FI. hence the bim...

Turbo-Brown
02-06-2007, 09:42 AM
Yeah I've had a purely mechanical engine (except for the spark). Pair of carbs and a clockwork dizzy.

It was rubbish! Couldn't be relied upon to start if the weather was even slightly unfavorable! :lol:

Hadrian
02-09-2007, 01:56 AM
Here's a picture of my tripple Dellorto DHLA 40 setup:

http://i80.photobucket.com/albums/j185/hadrianvcox/dellorto.jpg

peerless
02-09-2007, 02:33 AM
Yeah I've had a purely mechanical engine (except for the spark). Pair of carbs and a clockwork dizzy.

It was rubbish! Couldn't be relied upon to start if the weather was even slightly unfavorable! :lol:

Hmm I ran my 289 mustang with a Holley 650cfm carb, 4 corner idle, and no choke. Fire it up in the morning and bring the rpm up to about 1200 for a minute or 2, give it a good rev and I was on my way regardless of weather temperatures. I do admit I became good with the holley carbs, but once I found my setup I was golden. Plugs where alway's clean, consistant, and never fouled. I lived in the desert at the time so I would have to jet a wee bit fatter then here at sea level. If I came down the hill for longer then a day I could swap out jets in a parking lot in about 10 minutes. That was with a 292 duration cam with about .536" lift. Yes it hauled ass :)

Not argueing one way or the other, but carbs can be tuned to a happy medium. Fuel injection does deliver more efficient fuel control as evidenced by cleaner emmissions and increased fuel economy.

I say replace your wiring harness and see where that gets you as opposed to trying to swap in carbs and have a tuning nightmare if your not familair with tuning multiple carbs, which is not easy at all.

Flip_Side_the_Pint
02-09-2007, 04:39 AM
carbs scare the shit out of me. My dads Porsche has 6 carbs and hes always messing with them tinkering with whatever it is you do with them. He rags on me for my MS and EFI and I rag on him for his carbs. But I admit 280 N/A hp sounds amazing through those 6 44mm carbs.

heres a funny picture of him tuning them. I love the look on his face!

http://img.photobucket.com/albums/v704/FSTP/DCP_13-1.jpg

klrskies
02-09-2008, 10:37 AM
I ran Dellorto's on I/R manifolds on my GTI and the initial set up was brutal....much to understand with all the tunable circuits. After it was set up though, the only issue I had was keeping them synchronized. I ran year round, useing the cold start enrichment in winter for a few minutes at start up.

BMW03
02-09-2008, 11:35 AM
very interesting thread, posing points for both sides.

whodwho
02-09-2008, 12:08 PM
carbs scare the shit out of me. My dads Porsche has 6 carbs...

Technically only two triple throats but still a pain to adjust. I always loved the challenge of dialing them in, very rewarding when you could idle/rev without one popping.

klrskies
02-09-2008, 12:43 PM
I guess I like the fact that carbs are not electronic. I know Fuel injection is better from a performance stand point but I'm more comfortable with mechanical stuff than electronic...

Think how uncluttered and simple the engine bay becomes with carbs and a distributor. I guess it's a generation thing...those that grew up on mechanical stuff probably appreciate it a bit more.

whodwho
02-09-2008, 01:27 PM
...I know Fuel injection is better from a performance stand point...

I wouldn't totally agree with this, depending on which aspect of performance you are looking at. I think a dialed in set of properly sized carbs would have an edge on a modified stock EFI (stock/extruded manifold) in HP but EFI on overall drivability.

For carbs you need to have somebody tune them or buy a large selection of jets, emulsion tubes, venturies, etc. I had a turbo 2L aircooled VW with a 45 DCOE side draught and ended up with alot of extra parts for it.

You can't beat the flexibility and ease of tuning an EFI


MS Rules!!!

Madhatter
02-09-2008, 09:32 PM
the other manifold you were talking about earlier, pointing towards the bonnet, thats because its for downdraft carbs, not sides.

yahweh
02-09-2008, 10:46 PM
Here's a picture of my tripple Dellorto DHLA 40 setup:

http://i80.photobucket.com/albums/j185/hadrianvcox/dellorto.jpg


that manifold is really long. Did you make them longer for low end torque?

klrskies
02-09-2008, 10:50 PM
I've seen pictures of the triple downdraft setup, but it didn't have air cleaners in place at the time, so I don't know about hood clearance... I would think it easier to clear the brake booster with them however. Forcing the mixture to make that 90 degree bend into the head can't be as good as a sidedraft's straight shot for flow. How difficult is it to relocate the booster, or use a smaller booster with more clearance when useing sidedrafts?

yahweh
02-09-2008, 11:11 PM
Ive been debating rather to do a side draft set up or down draft. I know a guy with a set of weber side drafts dcoe 45's? i think and manafold. pm me if interested. I doubt if im going to buy them.. but may. i got a eta car with a 323 head and going to get a 304 ish schrick cam. These carbs wont be worth messing with unless you run a hot cam with a high comp pistons.

superj
02-10-2008, 12:02 AM
just get an intake from an e21 320-6 or e21 323 that was carbed and then mod the intake to accept a large 2 barrel or a 4 barrel.

i have almost collected all the stuff to run a weber 32/36 on my e21 with an m10 because i like the carbs too. i come from air cooled vws and mid 60s mustangs so i am more comfortable with them also. i can move to weber 38 which gives a major power improvement over the 32/36 but the gas mileage difference is more then i want right now. later on in life, i plan on running dual 40mm delortoes or dual 40 mm webers because getting the parts for m10 motors is very very easy on ebay.

i agree on how much i loved my carbs on my older cars. i, like peerless, never had any issues in warm or cold weather and i swapped carbs on my vws all the time because i used to love to collect and rebuild them. i would go to the junkyard and search through cars till i found something interesting and then throw it on after i rebuilt it.

i also got alot better gas mileage and throttle response on my 79 gmc stepside when i rebuilt my factory quadrajet carb after doing some smoothing of the venturis and reshaping then i was ever able to get with a holly or rochester after market carb.

yes, if you get dual or triple carbs, buy syncronizers because everytime you move one idle or adjustment screw then you are going to have to resync.

klrskies
02-10-2008, 05:30 AM
I converted a Honda to a webber 32/36 and it it was amazing how well it ran once jetted. I really like those carbs. The idle was rock solid, it transitioned well, and only required the mains to be opened up about .008 and it ran like a champ. Boy did it howl when I ran up the rpm's with the second barrel open with an open element air filter! Redline (Webber distributor) used to make a kit for the mercedes straight 6 that used two synchronized 32/36's on split manifolds that was intresting. I've never seen one like it for a BMW 6 though...would provide plenty of capacity I believe on a mildly cammed application. An I/R manifold with sidedrafts would be the ticket for cammed engines though. I'd like it once it was dialed in. I used to live in Tucson, AZ and enjoyed modifying Air cooled VW's there. A large VW aftermarket retailer there named "Chirco" was in Tucson, and maintained a good stock of webber carb componets. They let customers swap jets and air corretions out of used stock for a fee of $1.00 per componet, which made dialing in pretty inexpensive. I ran Dellorto's too, and found them to be more easily tuned, but they've been out of business for a while now. I believe "C.B. Performance" in California, another VW store, still has a stock of parts for them however. Very modern design compared to webbers.

bottlecape30
02-11-2008, 01:01 AM
I used to like working with carbs over EFI for a long time. Now that i have played with MS though and learned it a little, i have to say it is way better then a carb.

To the OP a few feet of wire and a handfull of sensors is going to be way cheaper then going to carbs to fix your problems. And with carbs you will end up with a whole new set of problems. I bet most mechanics today don't even know how to tune a carb, there all used to replacing an ecu box.

winstontj
02-11-2008, 11:03 AM
I did a search on this and didnt get much info. I read that its hard because of the break booster. But what else is there to know. I would really like to do this to the eta.
IMO bad idea to put 3x carbs on an eta motor. Eta motors are low revving, low compression motors and for the most part you will regret it because the most common carburetor you will be able to find is a Weber 40mm DCOE which you'd need to choke down into the low 30's just to make it work on an eta. Also the brake booster - Check out my project blog. I'm doing a booster delete currently. If you have a spare pedal box I could easily make up a second one but I think that most manifolds will work if you swap out to an e21 booster (like the one I'm deleting) as it is slightly smaller I have heard. http://www.e30tech.com/forum/showthread.php?t=47920 (Look at the last page) As for the manifolds... Send me a PM if you are interested. I ordered two manifolds from Rowland in South Africa. They are on the way to the states now and I'll be willing to sell one when I know the final cost to me including shipping. They are fairly short, keep the TB's level but are known to have problems with the brake booster.

carbs get rid of the electronics for the fuel and idle. ANd i have problems with that. It would be real nice and not to many people do it. So it will be different.

Is there any links or write ups or anything?
Not many people go back in time this way. Usually putting newer technology onto an older car works out best. How much experience do you have with carburetors? You mention you have issues with fuel and idle? Have you tried to get your eta running properly and tuned as is? What makes you think that putting tempermental carburetors (three of them at that) will make the situation better? Carbs are very tempermental, go in and out of tune easily, need syncronizing and you'll have three not two to deal with.

Theres no cheaper way i could go about this?
If you are looking for a cheap setup don't look to anything ITB. Plan on spending $2k for a proper carbureted 3x webber setup. Manifold, carbs, new fuel pump, mess with the motronic, o2 sensor, ignition, etc. You'll need a lower pressure fuel pump, adjustable FPR, you'll have to disconnect lots of wires... Usually if you have to consider price the answer is don't do it... if you have to ask - you probably can't afford.

A few other things to consider. Webers were made in Italy and Spain IIRC and most often in pairs. A common mistake is to go out and buy two sets of two (leaving you one extra) and throw three on an m20. Webers are all matched when they are made, matched at the same factory so you don't want to mix Italy carbs with Spanish carbs or you may run lean/rich on two cylinders. Also linkage fabrication will be interesting... unless you can weld/fabricate. You need to look for a set of three carbs that were made together from the same factory - try looking at some old 6-cyl datsun sites, Don't think Porsche will do it... Maybe you can find someone with an old Bavaria, etc.

Good luck and post up results!!!

grimm862
02-12-2008, 02:08 PM
wow, This thread is still alive too. I don't have the ol eta anymore. I now have a proper 325i. That actually runs good.

Really wished I coulda done more to my eta though.

whodwho
02-12-2008, 04:54 PM
Hmm, hadn't caught it was resurrected - one year later to the day...

klrskies
02-12-2008, 05:43 PM
I/R is always impressive....when done correctly. We have to be honest and accept that there's a considerable learning curve with I/R carbs. The carbs are so tuneable, and being so, require every circuit to be tuned to get good drivability. My sidedraft dellorto DHLA's were one of the most modern designed carbs and offered great performance. Not too many people are intrested in carbs anymore, with the introduction of stand alone engine management. Carbs are old tech, but the are a neat niche. It's probably us older guys that like carbs, as we grew up on them.

Hadrian
02-13-2008, 12:07 PM
IMO bad idea to put 3x carbs on an eta motor. Eta motors are low revving, low compression motors and for the most part you will regret it because the most common carburetor you will be able to find is a Weber 40mm DCOE which you'd need to choke down into the low 30's just to make it work on an eta.

That's a bad thing?

bataangpinoy
05-14-2008, 06:54 PM
sorry to revive this thread but what ever happened to mikuni carbs? there was a guys with a miata what had them and it looked bomb-ass.

klrskies
05-14-2008, 09:12 PM
sorry to revive this thread but what ever happened to mikuni carbs? there was a guys with a miata what had them and it looked bomb-ass. Webers are so well supported that they overwhelm everything else. I've messed with Webers and Dellorto's and Dellortos are a bit more modern design and a bit easier to tune, have nicer linkage and newer versions had actual seals on the throttle shafts. Unfortunately they went out of production years ago. I would bet the Mikuni is really nice too, but not very common. A person messing with a particular brand of carbs accumulates quite a few parts to tune with since virtually every circuit on the carb is adjustable. A big part of the webers attraction is availability of parts...Not that they're better, but economical and available.