740 carb review also known as DFT DFTA weber

[joedrum]

Okay I am going to switch gears a bit and talk manifold. My belief here as it pertains to oldwings and their smaller displacement than this carb is made to supply. On the stock carb set up, the carbs are close to the intake runner inside each carb it narrows down to 1"ID where the atomizing takes place. It is also really very close to intake valve. Only a 180 degree sweep from combustion chamber. But it's not right on top of the head. When a carb gets too close it is in the a lot turbulence from the stroke of the piston volume. It really makes it tough for the carb to make consistent fuel charge from the all the trauma the carb right in the middle of it. Same is true when to far away. Except the carb suffers from not enough effect on it to atomize consistent fuel charge. So there is a sweet spot where the carb is in perfect tune with motor. Is this adjustable ??? Yes it is. It's like jetting the carb right to get it to work good. With the "oldwing motor and the idea of one central located carb as compared to stock set up is about 2 easy and maybe three times further away from piston.

It is not good to think this don't matter but it does the farther away from piston you go the less and less suction you get. More coming.

 

[joedrum]

Some pics of manifolds ...

This is mine. It doesn't have the pvc collars anymore. But right where pvc was there are 1" sleeve chokes downs at the type4 outlets to speed the air speed up to compensate for the longer runners to have same pull on the carb as if it was closer. From there it opens back up to 1 1/4" to the piston. This worked good on my bike.

This is a pic of the bought pieces in the rubber hose set up. This pic is of westgl set up. I believe this set up has chokes like mine and is basically the cheapest way to get this setup in operation. This set up seemed to please westgl a lot. Like me he has tried to improve on this and is having trouble making something better than our first set ups. I was really impressed with westgl work as he made the best of the conditions he has which is huge compared to most of us. Nice work.

Now here's a set up Dan's come up with on his bike and is really the stir right now. As for runner size it's 1"ID from type 4 to the heads. It's also getting huge power at high rpm. Pretty much debunking the high rpm myth that most thought it would suffer. Dan has also got heat at the type 4 from coolant source. This has been big boost to it in running smoother and with quicker warm ups. The issues left for Dan to deal with from here seem small. Just dialing in carb to its fullest I'd say.
More examples coming :mrgreen:

 

[joedrum]

This is one of the best ideas that came along. This is the bathroom grab rail runners on type 4 plenum. It"s not that hard and quite slick. He has no choke in his and says it runs good and lots of torque.

I couldn't find a good pic of jungo set up. His pics are videos his system is another one with rather full size runners just a bit smaller than 1 1/4". I like the simplicity in his metal runners and bends.

Pic of jungo runner making.

This is a pic of westgl build his first one. It doese have chokes in it. Nice work. So these are all good examples that are running and influenced here. As they were built.

 

[dan filipi]

Heat has a profound effect on the carburetor and how it's adjusted so I think it should be mentioned in this thread.

Gas simply sprayed into the plenum will not vaporize.
What is needed is a vacuum in a flow of air.
A vacuum like exists under the throttle plate, lowers the boiling point of the gas liquid.
By lowering the boiling point, only then can the raw gas introduced into the manifold vaporize. Vaporized gasoline is what burns. Raw gasoline is more wasted than burned.

When heat is added, the raw fuel is vaporized much sooner and faster. Just like on warm days the first start of a cold engine is easier than on cold days because there is more heat available from the air being drawn in.
Heat together with vacuum is what vaporizes the fuel.

The flow design of the vw plenum is directed such that heating the floor of it will drastically increase vaporization of the fuel.

How does this all play into the carb?
Well like magic, the jetting can now be made leaner.
A leaner fuel to air mixture means better fuel economy.

The Weber 32/32dft is of superior design for jetting through all its rpm ranges and throttle openings from idle to redline.
With this jetting ease, we can customize the jetting to the entire manifold.
Without heating the plenum, I believe there is no way to achieve mpg comparable to the stock carbs of 40-45 mpg.
Runner types and air speed come into play here also but the Weber gives us options, and does so well.

 

[joedrum]

Yes Dan and I have spent lots time talking about heat. And I'd say he's totally right if conditions are like winter so to speak. It's not good time to try and jet the carb without heat. Now in perfect conditions in a controlled environment yes or if that's what mother nature is doing anyways. I know I had days here where it was wasn't what I call warm but the air was so dry. Hooch ran flawless. So a lot of things figure in here.

Sheesh looks really rather easy build dan did here seems the parts are just right.

In this pic you can see the older type 4 has the threaded hole in the bottom. The newer ones don't.

90% of whole deal.

I like the set up. It's obvious to tell. This is not a big deal. Just a big helping of do it yourself. In conversations with Dan this system has huge volume and heats rather fast. Dan didn't take long getting this done.

There are other ways to heat and they have been talked about. But this is a working example.

 

[joedrum]

there has been a new recent development of the benefits of the transition plate from one barrel carb to two barrel carb ...when used atop the type 4 plenum. You need a plate to transition the type4 intake to a single carb mount ...that centers the fuel charge after it leaves the carb between the runner outlets ... it also raises the carb about a little less than 2" ...the actual transition piece is 1 5/8" tall ... it also tapers down from 2 barrel oval to single barrel circle ... effectively making this a choke down in the 1 5/8" height it has or condensing plenum....I have two of the transition pieces here with me as I am working on two bikes with 1200s in them and singles added ...they are nicely made for the money....

this system when added to bike that was doing very well ... got better ...this was proof that it was a benefit ....

 

[joedrum]

okay lately we have been talking how to get the best from weber carb....on dans bike we have made some great moves ...first the transition plate adapter and effective choke down also raises the carb up some .. giving the carb a better strait pull down out of carb before having to make the 90 degree turn in the plenum ... this is the best place to have extra volume as the carb works better and quicker this way...then we started going for maxium jetting talk ... and after a bit dan mention the weber book starting point for the carb to be dial ....this was 200 air primary ... 180 air secondary ...we got the primary jetting 200air---135 gas ... we havnt gone to secondary yet ... but it seems dan getting good results from the test rides he done ...

it is my belief that adding as much air as you can to the weber and gas jet the biggest you can with no ill effects will get the best atomization you can get with the weber.... it seems to be playing out this way also so far ... we are trying hard to really figure this weber single deal to upmost best :mrgreen:

 

[joedrum]

the band x member and self proclaim single carb guru ...who was booted off the forum for disruptive spoiled brat mouth child like comments on stuff he had no knowledge of ...has not learned a thing ...

dan our forum leader here sent him a pm trying to this child acting man to relax ...I told dan ,,,this child of a man would answer with some shitty mouth answer and he did ...

just what part of this manifold is yours ...lets see you make the plenum no...you make the runners no ..they came with the kit you bought ...

did you make the carb ...is your last name weber no ... did tom make the carb no ... dose all the empty claims of your trashy demeaning tech blab give you a monopoly on all single rights ...LOL no

is there anything in weber info that would back your claim about this carb not being touched going from a car to motorcycle motor ...of course not... webers are made so they can be fine tuned

people with common sense im sure are questioning you ... your BS tech mouth makes absolutely no sense ..but I will start now posting that no one call you ever about single carbs ... as this would please me too.... cause I get tired of responding to your complete worthless BS that spews out of your mouth ....

I must congratulate you as the number 2 reason why single carb mods have been so unsuccessful over the last decade ....

I like what west posted at ngw aitch has been removed when he went after cyborg .. and said no one has the right to stop or discount someone else project and how thet do it if you don't want to see it don't look ...sheesh I thought for sure this fit you cm85 better than than cyborg bigtime

hmmm ....trash talking sucks .. you and your gang of fools are so far back I dont even care ...only a complete fool would tout no carb tuming in the most tunable carbs made on the planet bar none you complete fool ....

personally I think tom is more upset with your BS not people from here and you know it ... your mouth has been a problem as soon as you were born its pretty easy math ... you like numbers blocks hammers a square heads pounded through round holes ...

I never and I mean never considered your BS tech on my single setup ... in fact im a caveman tech guy ...and I enjoy beating papered brained fools....and sure don't do that by listening or following such stupid thinking

 

[joedrum]

well seeing how this thread is about learning the weber carb ... it is getting a lot of attention from people on another forum who think that its a crime to adjust a dft carb bought from this special supplier ....like he thinks he owns the rights to a design he bought from a vw supplier ... sheesh

anyway if you guys buy a carb from tom don't ask question at Saunders, the answers are going to be here ...if you want carb info cause these people don't want your question are bothered by you I guess

we do things here because this is the thrifty forum and unsponsored and is dedicated to helping the small people get there bikes going on the least amount of funds

this obviously rubs these people wrong .... its just foolish as can be to tout not adjusting the most adjustable carb out there ....sheesh this is what I wanted something that could be dial in cause it design is capable ... I am sure the weber people would laugh at such nonsense

I am sure if your idea of running good is low enough ...then what they are pushing is ok ... I don't do these mods for ok ,,, I do them to be better than before ... dose it always work no ... dose it always fail no .. I think my bike and the recorded record on this forum proves that I am very determine to get where I want a project to be ...

so I advise just not messing with the people who have not even opened the carb up and treat them as expert opinion there just discounters ..ive never heard one piece of good advice from people who think like that ....
...they sure don't influence the determined but they sure are going after other people by discounting people who do what weber suggest to do period ...best day to everyone :mrgreen:

 

[Omega Man]

:0fftopic: Thanks Joe, now back to the carbs and manifold.

~O~

 

[dan filipi]

My advise for anyone buying a Weber DFT is to put it on and try it.
You might find it runs real well but if not, Joe and I know how to straighten it out.

 

[wbishop]

Thank you guys for sharing all the great info and offering the help! I'm putting Langdon's 32dft on my bike this week and am hoping to get it going with little adjustment but it's reassuring to know there's a great group of folks here willing to help!

 

[joedrum]

sheesh i had forgotten how good a thread this is :shock:

 

[joedrum]

it has been about a year since the last meaningful update on this thread ....personally ive learn a lot in this year ...

there is nothing off topic about people that post beliefs that are totally baseless and simply wrong ....

in this year of one man being me that ignores what others say ... and simply only get answers through the actions that i do and observe myself ...as my signiture says ...hot air dose not run a oldwing ....there is lots of hot air in the topic of putting a car carb on a oldwing4 ...pro and against ...only someone like me who listens to no ones blab is this area can find the truth as with any issue ...if your not in the arena you cant possibly win or loose ...

people who want to believe honda made the best set up and cant possibly be bested have that right ...people who believe the car carb is perfect out the box because weber cant be bested have that right also...

personally i dont believe any of that ..this is not a discount its a warning to be careful with the info out there

there is also the belief that all carburators are some kind of stone aged device and only fuel injection ran by a computer is the only good mix for fuel

the people that believe all the things above simply need to quit reading this thread and move on ...there is simply nothing after this you will agree with ... i care not to debate hot air

CV carbs can simply not compete with the basic stone age design strait carbs ...adding mores things to the mix to make a carb atomize gas simply makes them slow reactors ....this 100% the reason stock oldwings stumble and have no power in low rpm ....this the whole reason why long time oldwing riders push the fact oldwings need to above 3000 rpm always to run good ....low rpm just will not allow cv carbs to do the job ....and they labor ping and knock to any stress at low rpm

strait carbs that dont use vacuum in operation dont have this problem ..enter the dft car carb ....2 stage carb progressive carb at that ....meaning it is two carbs in one ... i wont touch on this a lot cause it takes just one sentence ... a 2 stage progressive carb in a high rpm motor set up covers the entire rpm capability of the oldwing motor has better than a one barrel strait carb .... most fail to see the 2 stage carbs also controls the air flow through rpm range ... cut air flow in low rpm and adds air flow in higher rpm ...usually double or more.....again ones who want to believe one barrel can do this have the right too .... the next post will all be about dft carb on oldwing and how to match it up in joedrums opinion with working motors on video for ones to see the results ....

 

[joedrum]

ive learned a lot about the dft carb in my work with it ... it mostly all learn in results as they came by trying things ....the dft carb was made for economy cars of a bit more cubic inch size and much lower rpm range ...jetting and the size of the different circuits in the carb and also the progression of the carbs in the linkage is all setup for this economy carb package ..weber also had to satisfy epa deals also ....

it is not a strait carb in the purest form ....things like the power valve witch is not adjustable ...need to be remove from having influence on the its operation ....the auto choke is another thing i dont have set up either as in the most open position blocks some air flow ...me personally want the highest of performance wont stand for that ...and the simple throttle lock on a bike performs warm up without airflow decrease....and is my way of doing it ....

the weber idle circuit is not only idle it is off idle too ...when it comes to the dft carb ...to me the is the biggest mismatch to the oldwing motor ....and is where i do my biggest mod to the carb to match the oldwing performance capable motor ...

the mod is an air mod to the carb ...in the idle circuit of this economy carb there is simply way too much gas provided for the somewhat small oldwing motor and it will run rich ...the mod i made quite some time ago ..i thought might just be for my modded oldwing 1200 motor...and may not apply to other oldwing stock motor ......ive come to the conclusion this is not so ....idle is idle no matter whats going with motor capabilities stock or modded like hooch ..... i will try to find pics of the mod i did for next post

 

[joedrum]

i have simlply not taken a picture of this mod ... ive got to get in some wood ...and i think i can take a pic of this mod from the top side as all carbs with this mod are mounted on motors ...

 

[joedrum]

the pic didnt work ... so i will have to mod the carb i have to do ...and take pic then ... the mod is a hole in the throttle plate of the primary barrel ... the hole i finally ended up with was quite big and is 9/64" hole ...this brings air to the over rich idle circuit as it apply to the small oldwing motor ...this also really changes how to look at dialing in a dft carb in the info weber puts out as how to ...it changes the whole concept of the carb .....

my theory in carb tuning is ...you have to to get a carb to perform at it weakest point ...that being idle and just off idle the best ...if you dont it will struggle to get going ... this mod actually seperates the idle and the off idle response in the combine circuit of the dft ... you can actually with this mod control the idle speed on the dft with the mix crew only and throttle plates completely close over the idle transition holes along throttle plate line up ...weber info is a mix of the 2 ...mix screw setting and idle speed speed screw on linkage ...
it also takes some of the dialing info by weber off the table ..as it apply to idle jet size ..and trying to stay within 2 turns on mix screw from close position and also 2 turns on idle speed control after it comes in contact with linkage .....

on the jyd build i am doing now the 50 jet seems rather close ...my method of tuning is to get mix screw to idle bike...this is usually more than 2 turns out .......then see how it responds to off idle throttle romp .......

 

[joedrum]

okay now we get to other things ...my theory on primary barrel tuning ....and this is ... the more air you bring into main jet tube in the primary barrel the better the gas charge atomizing will be ...this is really important ..cause if you dont get out of the blocks good you already lost the race ...and taking off is the where the weakest moment is ...stock carb racks have proved this dang near 40yrs now of stumbling out of the blocks trying to get going ....so in the stock set up in the dft economy carb deal the secondary and primary air bleeds are way off actually backwards in my view ...220 air bleed in secondary ...160 in primary ...

first for me is switching these air bleeds 220 in primary and 160 in secondary ....

ok after this is done bike is idling good from mix screw and 220 air bleed is in time to check off idle response ... most likely it will bog ....the theory of working to the 220 air is the trump card here and dosnt change ... so you increase the main gas jet in primary till it get to where the bog off idle disappears ... this seems to around 120 gas jet on the hooched out 1200 motors probably about the same on stock bikes too we are very low in rpm and not much air flow for there be to much difference...once you get good primary action not perfect action just good personally i like to dial in the carb with airbox off ...so i can look into see if there is any raw gas present ...if there is something not right..... atomize gas should be all you see ....but in this condition perfect is not what you want that comes a little later ...you do want it to be close ..having a bit to much air is not a bad thing so slight bogging in repeated revs is not bad thing...as when the airbox gets put on air will be cut some and instantly improve this .....

 

[joedrum]

next is the secondary .....it seems like for the 32-32 dft carb the 60 idle jet in the secondary is fine ... on the 32-34 dft in hooch it is 80 idle let ...but anyway 32-32 seems to be 60 is good ..i certainly cant see anything smaller working good but one never knows and it pretty hard to really test this good except on ride tests where cruising at speed and slight secondary opening is where you are at ...or if you go top performace mode for carb like me you have modified the carb progressive linkage to come in earlier to mod it to a more performance carb as oppose to economy carb .....hooch and jyd are both done this way and come in about 1/2 throttle position instead of the 2/3 position of stock dft ....

anyway with the 160 air bleed in the secondary as oppose to the 220 ...you have increased the gas feed to the secondary already and you dont necessarily need a big air bleed here with the oldwing motor as the higher rpm has really bought in the air big time and gas flow is the biggest thing on the table to get the secondary working good the jyd biuild at this moment is at 140 gas jet along with the 160 air bleed ... this is night and day difference from the stock set up of 95 gas jet and 220 air bleed huge difference ...

actually if you cant get good secondary in no load condition you will have no chance under load ...... so you want to work here good in no load position .... rev hard big time when secondary kicks in

as before you want air box off and while kicking in secondary you want to be able to look into carb and check for raw gas ...this is the spot that this will happen the most in the dialing in ...if you pass this test here you are getting really close in dialing in ...

 

[joedrum]

if things are looking good ... up to this point ...it is time to put the the airbox on and run it again no load ...now you can really fine tune the idle and off idle really good in its final set up mode on the jyd build i actually ran the mix screw in a bit as air box install richens things a bit and also just a touch of fast idle that seemed to add to the off idle response touch meaning just that ..i barely moved the throttle plate from the fully closed position .....

is it perfectly dialed in ..id say no but it will just be tweaking things from here ...and if there is another jet move somewhere you will know it. a lot now and where to ride the bike under load to figure them out .... the next post will more about the mods made to the carb and pics wont be today i am done for now :thanks: