45 dcoe help!

[TheDriver216]

Well i installed a weber 45 dcoe from a forum member.. everything is hooked up.. problem is when i start it it it runs fine with the choke on.. 2k rpm steady no problems.. now when after i let it warm up and close the choke it accelerates up to about 3.5k rpm then comes crashing down and dies.. any ideas?.. i was told it ran before it was pulled off. new to weber carbs.. i havnt advanced my timing yet either ..

[djjjr42]

For starters you need to find out what size idle and main fuel jets, air correctors, and venturis you have in there. Do you have a pressure regulator installed? And an aftermarket fuel pump? I've got the same carb installed on one of my FB's so I know a pretty good bit about them. The Sterling I just won is for another FB project.

[TheDriver216]

well i got it running pretty decent right now.. after doing some online reading.. the idle jets might be too small for the fact of how far i had to turn the mix screws out to get it to idle.. i have an aftermarket pump(cheapy mr. gasket till i buy another good one) a mr gasket FPR set at 4...my timing is 24L 16T at full spark advance. and its pretty accurate since i have a timing light that has a setting for 2 cycle and the digital spark advance.. ill pull it apart as soon as i can to see what i have in there or email who i got it from. it was bought brand new from racing beat about 5 yrs ago but i dont know if he changed anything inside.. im just happy its running pretty good right now.. runs like hell after 4k rpm.. get a bit of popping during deceleration but that can be i need a new exhaust.. any more input would be great

[djjjr42]

Those mixture screws should just be used for fine tuning. Make sure you have the idle screw set properly. For the jets it is easy peasy to find out their sizes. Just twist brass tab off that circular piece on top, and the 4 jets are right underneath there. All you need is a flat head to pull them out. The mains (big ones) pull into 4 pieces, have emulsion tubes in the middle, fuel jet on bottom and air corrector up top. They slide into the top piece that's threaded. The idles are just 2 piece with the jet on the bottom. You should easily spot the stamped markings on each piece to see what sizes you've got. I'd recommend giving them a thorough cleaning, especially if the carb sat for a while. For the venturis you may be able to peek in through the barrels and see them stamped on the edge, but they are behind the aux venturis (where the fuel comes in). I had a lot of fun pulling mine apart when I first got it, and rebuilt it with a new gasket set (pretty cheap). Just be careful with the screws on the top plate, and remember you are working with aluminum, so don't over torque anything.

Runs like hell after 4k rpm... as in like shit or like a bat out of hell? Unless you and the guy live in the same climate and at the same altitude, you're probably going to have to change some jets to make it run right. Luckily they aren't that expensive. Venturis and emulsion tubes are a little more pricey though. Keep in mind that every engine is different so what may work for someone else may not necessarily work for you. I am using a wideband sensor and gauge, that helped me out a ton with tuning. It's hard to really tune by ear, feel, or otherwise.

What type of exhaust are you running? I use a full RB system with mine. If you're on a stock exhaust you aren't going to gain much power from that carb alone, because the stock system is really restrictive.

[tom93r1]

wide band makes things 1000% easier. Its possible without but you never really know for certain where you are with things and it takes much more trial and error.


To rebuild the Weber is very easy. Its about 6 o-rings and 2 gaskets or close to that. I have done mine a couple times and can completely disassemble the carb and put it back together in well under an hour. Like djjjr42 said, be very careful not to strip anything out.

One thing worth checking that could possibly lead to some popping, pull the filter off and look down the barrel of the carb. If you see any fuel dripping the float is probably adjusted too high.

[djjjr42]

+1 on the wide band comment. Also this may go without mentioning, but re-check everything connected to the carb. Vacuum leaks can cause all kinds of problems, so check your brake booster line for any cracking or excessive wear, and make sure that your connections from the carb to the manifold and the manifold to the engine are properly torqued.
What kind of manifold do you have? I know you said the carb came from RB, and if the mani did too I guess it's a 2 piece? I have a 1 piece wraparound, but there is also one from Lake Cities or something that is really short, in which basically the carb is beside the engine rather than over the top of it. Is your vacuum advance from the distributor hooked up, or do you have it open? Also (and this has nothing to do with the carb's performance) but do you have the oil lines from the OMP hooked up to the mani? I don't mean to offend if you already know that this is critical to the engine (unless you're using premix). I'd just rather be safe than sorry when giving advice!

[TheDriver216]

Exhaust= Rotary engineering header/presilencer(2-1 collector) then it looks stock midpipe to a magnaflow muffler.

Omp is hooked up and running.. make a custom rod out of a 5gallon bucket handle. at full throttle the omp is all teh way open (i can see the pumping through the lines) i plan on switching to premix

Vacuum leaks.. i hooked everything up and sprayed teh shit outta it with carb cleaner and nothing happened so i feel im safe there.

Runs like hell after 4k= holy shit that pulls nicely.. only lots of popping on decel.

No Vacuum advance- im running my timing at full advance 4k rpm is where i set my timing 24L 16T.. as suggested by others.

Manifold= one piece wrap around

Guy i bought the carb from lives 30 min away so climate on carb tuning is not an issue..

Wideband is next purchase on the list.. well that and an ignition box.

Insulting my intelligence--its cool need to cover all bases.. ill pull the jets out tomarrow and see where im at.. its seems to be running super rich..

[TheDriver216]

well here is what i have in there..
Air Corrector-- 175
E-tube-- F11
Fuel jet--180
Idle jet--50
Venturi-- 40mm
Acceleator pump jet-- 85 F9


After reading some stuff from Rotary shack robert on the other forum.. for a stock port i should change the e tube to an f7 and use smaller venturis..

ok what are you opinions?

oh and my exhaust backfire seems to be due to exhaust leak when i rev the engine i can seem exhaust gas/smoke come from by the header gasket..and witht his carb i seem to be getting more smoke out the exhaust then when i had the nikki on there

[djjjr42]

Nice omp rod, I used a coat hanger!

Ok, well you will still need to tune and change jets based on the season for optimum performance and to get the most out of the carb, denser cold air needs more fuel.

Robert knows his stuff. I will add that any recommendations as fas as specific sizes will just get you in the ballpark. Keep in mind that if you change the venturis, you will also have to change the jets. Different size venturis will yield different performance characteristics. The 36's will give you more low end grunt, but you will lose out on higher RPM power, in fact it will take pretty much forever to go from 6k to 7k rpm, lol. You wouldn't need to go lower than 36, for sure. On the opposite end of the spectrum, going without any venturis (making it a true 45), you will lose low end torque big time, but it will scream like a banshee in the upper RPM's. You'd think it's going to stall out between shifts though, it's pretty rough! So for me, I got a set each of 36, 38, and 40, and a bunch of different main jets and air correctors. I also got 3 different sets of idle jets. I will try to get out in the garage in the next couple of days to see exactly what I have, I can't recall off the top of my head. But in essence you can tune the car to run with different size venturis, it's all about your personal preferences for performance and drivability. Is it your DD or just a car for fun?
The DCOE flows more air than the stock Nikki, so if you take more in, more is coming out. How optimum the air / fuel mixture burns is what the tuning is for. The engine is basically a glorified air pump, so once you've opened up the exhaust, the stock carb becomes a restriction on how much air you can pull in.
What color is the smoke? Black smoke means its running too rich. It will also reek of fuel.
I don't know what your budget is, but if you want to start out cheaply I would just order some main jets and air correctors from ebay, Pierce manifolds is on there. Get a few sizes of each, some smaller and some larger than what you've already got.

[TheDriver216]

and my accelerator pump jet i think i posted wrong.. the one under the plate(next to the ap rod) is an 85-f9.(what is this one called) but the one on the outside of the by the barrel is a 65... and im getting all of my instructions from here http://www.teglerizer.com/dcoe/weber_service_manual.pdf

the vehicle is my daily but i can adjust my driving style i rarely cruise at anything less then 3.5k rpm .. im thinking of sticking with the 40mm venturi... im gonna order large idle jets.. smaller 2 sets of smaller AC jets, maybe get the f9 e tube and my main jets should be from my reading of other people.. i know its gonna depend on what i want but i need to start somehwere.. i like teh way it pulls after 4k i just want lean it up on the lower end a little.. i can smell it lol.. and a small flat spot around 2.5-3k pm.. what causes that? the smoke isnt black and its not the oh shit burning oil blue.. and im not losing coolant.. after wam up it really only happens when i get on it polly from running rich down low.. well any more input is greatly appreciated

[TheDriver216]

well i ordered some 38 venturis a few jets here and there around what i have already a f16 etube(as robert suggested leaner on bottom richer up top).. so they should be here by monday and ill start playing to get it better

[djjjr42]

Cool. The flat spot is caused by transitioning from the idle circuit to the main. You should be able to tune that out though. If you're sure that you're rich down low, you need smaller idle jets not bigger ones. However iirc I think my 3 sets of idles are 55,60,and 65 and you said you've got 50. Like I said without a wide band it's really pretty much a lot of trial and error. There is an old-school method of reading your spark plugs, but the procedure is like drive 60mph, immediately pull over and pull the plugs out, lol. Another tip, make sure you keep a log of the different combinations and your observations of each.
Oh yeah, I haven't seen that guide before, cool that you found it.

[TheDriver216]

well a small update.. went and put in a 60f9 idle jet seemd to work great.. the 50 i had in there wasnt marked with an f number and looked twice the size of the 60f9... put in a smaller main jet to lean it out all the way through (went from 180 to a 175) and it made a hell of alot difference it seems to be a lil more ballsy i can chirp 2nd again lol so i think it was too rich... drove it hard down the freeway and came home checked the plugs and they are a nice mocha color.. not gonna mess with the air correctors till i get a wideband.. all in all im happy with what i did... i havnt change my venturies from the 40's to the 38's yet.. i do want a lil more down low but it seems like a pain to change them and i didnt have time today.. from 2.5-4k rpm its a lil weak but after that it screams.. and there is a tad less back firing i still have a small exhaust leak at teh header to block tightened it down and got rid of some of it ( time for a new gasket)

and while i was at it checked my compression and both rotors had a nice 100-115 3 even pulses.. woot woot plenty of life left at 116k mile

[djjjr42]

I'm glad you see a difference. It goes to show what a small change can do. As far as changing the venturis, it's actually not that bad. Just loosen the 4 screws underneath (a pair for each barrel) that are connected with a little metal strap for each pair. Then reach in and pull out the aux venturies, and then the main venturis are behind them. Make sure when you replace them that you've got the little dimples lined up with the holes. After you get those screws out and pull the aux venturis you will see what I'm talking about. Also be careful when putting them back in, if you over tighten the screws you can crack off a piece of the barrel body. Don't ask me how I know! I also suggest using a bit of teflon tape on the threads when you put them back in, and keep the metal straps that link each pair, on. Keep in mind that when you change the venturis, whatever jet combo you're currently running will not be optimal. So you may want to hold off until you can get a wideband. Or, you can do a lot of trial and error with different combos, and keep a log of your findings.
Regarding the plugs, you can't really get an accurate reading if you drove it hard and THEN came home and checked them. You'd actually have to pull off on the side of the road after running it hard to read them. Like I said that method is pretty impractical and a PITA.
I was supposed to tell you what jets I have, but I got sidetracked with another FB that came into my collection last Friday. The Sterling is going in that one! :)
I'm pretty sure my biggest airs are 205 and the biggest mains are 195. I think I have an assorted range of about 50 below each. And the DCOE is on a stockport 12A in an 83 GS with 45k original miles on it.

[TheDriver216]

well about driving it hard the freeway is oh 30 seconds from my house so it was a hard drive to and from the freeway absolutely no low speed lol... but it does feel alot better, the wideband i was looking at is http://store.summitracing.com/partdetail.asp?autofilter=1&part=EDL%2D6593&N=700+400065+302787+115&autoview=sku

but i also seen this and it has logging capabilities but im short a laptop at the momenthttp://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2DG2995&N=700+400304+115&autoview=sku
would the edlebrock one be sufficient for my needs since im really not running efi that would require a log?

[djjjr42]

The first one is just air/fuel, not wideband. As you see it only operates in a very narrow band, from like 12 to 15. I guess it might possibly work, but if you are really far off you won't know it, i.e. very lean it would only register 15, when you might really be at like 19 or something. The second one you listed is a wideband, and the same one I have, I believe. Innovate LC-1 with gauge. You would only need a laptop to do data logging. But while you're spending the cash you might as well get what you need and have more functionality, plus the gauge with the wideband would mount in a pillar pod. The pods are only like $25, and come in single or dual mount, and it actually replaces your entire pillar trim. I got a dual and have a Autometer D-PIC gauge in the second one.

[djjjr42]

This is the exact wideband/gauge combo I bought. I think the gauge is also available in red:
http://cgi.ebay.com/ebaymotors/Innovate-Wideband-LC-1-DB-Blue-Gauge-Kit-O2-3795-NEW_W0QQcmdZViewItemQQcategoryZ33557QQihZ001QQitem Z110245382869QQrdZ1QQsspagenameZWDVW

Here is the pillar pod:
http://www.gaugepods.com/mazda.html

[TheDriver216]

Most likely ill drop some cash on the second one in 2 weeks or so... im trying to plan a trip to germany for june right now.. thanx for all the info.. when i get to actual number ill be back for where to go..

[djmtsu]

Just thought I would post here since I have a 45 DCOE now. It is on an old school 13B 4 port (stock ports), road race header.

I know it came off a FB, but thats it. It has the 36 chokes. Hope I can get it running good once it is on.

[730RWHP12A]

glad i could help! in order for these carbs to work good the jetting has to be spot on...

[djmtsu]

Alright, so what do you recommend for:

13B 4 port
FB electronic dizzy conversion
Road race header, silencer, catback

Carb is a Weber 45 DCOE with RB upper and lower intakes :)

Keep in mind this is also a Cosmo, not a 7 so she is pretty heavy. Also, would need to work well here in Middle Tennessee as well as the elevation of Deals Gap (not bad, from 877 to 1962ft)

[730RWHP12A]

65 f9 or 70 f9 idle jets

f11 e tubes
190 main fuel jets
180 air corrector jets
0 bypass accel pump jet

venturi size will depend on where you want your powerband to be

38-40mm venturis will be good for lots of midrange power,and good driveability. bigger venturies will give you more peak power but your mid range will suffer

[TheDriver216]

wow... brought it back... tis been 3 years almost running the 45 i love it... its still on a 12a... the 40mm chokes really come alive up high i never did get around to changing to the 38's because i loved where the power came on at... i have a s5 6 port that i plan on swapping in... Rob will those specs work out for a 6port as well? and will a 45dcoe be able to handle a streeported 6port with sleeves removed? or is stock about as much as it can handle?

[730RWHP12A]

wow... brought it back... tis been 3 years almost running the 45 i love it... its still on a 12a... the 40mm chokes really come alive up high i never did get around to changing to the 38's because i loved where the power came on at... i have a s5 6 port that i plan on swapping in... Rob will those specs work out for a 6port as well? and will a 45dcoe be able to handle a streeported 6port with sleeves removed? or is stock about as much as it can handle?

the 45 will work good on the 6 port and the jetting should be about the same..
on a ported 13B a 48mm gives you alot more power potential over the 45mm

[djmtsu]

Yeah I brought it back. Yay me!

I just want my shit to run right, and I am tired of sifting through all the BS on the 7club about carbs. I figured Rob had seen it all, and would know what set up to use.

Thanks guys. This weekend I am taking the carb apart to see what jets/tubes it has in it. Can you get those parts, and Weber rebuild kits??

[TheDriver216]

i get most of my parts from 2 places
http://www.carburetion.com/
http://www.webercarbsdirect.com/product_p/92.1047.05m.htm

[djmtsu]

Thanks man. I went ahead and ordered the rebuild kit and a new set of soft mounts.

Question..when I get into the carb, if it has the old brass floats, should I replace them with the plastic floats? I hear they are better.

It is a 45DCOE 152 if that makes a difference.

[Fidelity101]

65 f9 or 70 f9 idle jets

f11 e tubes
190 main fuel jets
180 air corrector jets
0 bypass accel pump jet

venturi size will depend on where you want your powerband to be

38-40mm venturis will be good for lots of midrange power,and good driveability. bigger venturies will give you more peak power but your mid range will suffer


my 13b street port has
205 fuel
200 air

44PHH mikuni side draft style.
very thirsty lol. But it also is 8 degrees outside. I think it has 40mm venturies...

[TheDriver216]

Thanks man. I went ahead and ordered the rebuild kit and a new set of soft mounts.

Question..when I get into the carb, if it has the old brass floats, should I replace them with the plastic floats? I hear they are better.

It is a 45DCOE 152 if that makes a difference.

Mine had plastic floats already, think the brass ones are in the ida's but it might also depend on how new it is.... its only 5 or so screws to pull the floats out.... ... and the only benefit i believe for plastic is for blow thru applications... Rob would have to confirm..

[djmtsu]

Well, I am hopefully get the chance to pull it apart this weekend, but I ideally want to wait until the rebuild kit gets here. I need to clean it externally as well. I doesn't look bad, just has some grime on it.

[fire85gslse]

Well, I am hopefully get the chance to pull it apart this weekend, but I ideally want to wait until the rebuild kit gets here. I need to clean it externally as well. I doesn't look bad, just has some grime on it.

I need to do the same with one of my dell 48's before Auto X season kicks in

[730RWHP12A]

Mine had plastic floats already, think the brass ones are in the ida's but it might also depend on how new it is.... its only 5 or so screws to pull the floats out.... ... and the only benefit i believe for plastic is for blow thru applications... Rob would have to confirm..


the brass floats lead me to believe its an older carb as all the new sidedrafts come with the solid phenolic floats. the brass floats work fine. the solid floats are only needed for boosted applications:p

[TheDriver216]

the brass floats lead me to believe its an older carb as all the new sidedrafts come with the solid phenolic floats. the brass floats work fine. the solid floats are only needed for boosted applications:p

thank you for the confirmation... :biggthumpup:

[TheDriver216]

Any updates on the rebuild? did you get the kit and were your floats plastic already?

[djmtsu]

Sorry guys. The rebuild kit came in last Monday, and I have been out of town for work ever since. I get back home Thursday night, I hope to tear into it this weekend!