Quirks of Mikuni/Solex's and Webers

[sillycar chick]

Was doing some research on the DCOE webers, and came across a very informative site. Its dcoe.net. If you follow the links to "tuning/guides" and then at the top of the contents "Selection and tuning of Weber DCOE carburettors" you will find a very informative article about selecting sizes of venturis, jets and emulsion tubes etc to suit the size engine you have. Well worth the read.

Afireman1, check out the site above i previously mentioned, its a very informative guide about how to set up your webers AND basic jetting sizes

Rodger and Billzilla thanks for the info I will have a tinker around on the weekend and see what is going on I am having fuel-cutting-out and spluttering issues at the moment but it may be fuel pump related

[Esteban]

Yes please I agree, Mods can we dedicate a Solex/Weber/Dellorto thread?

Did this ever happen? :-)

[Billzilla]

Damn fickle Webers hey Billzilla

Sometimes makes us wonder why we just don't use those complicated programable thingies that everyone else has problems with

Regards

Rodger

BTW, a quote from my very first post in this thread ->

The other nasty thing the Webers have that the Mikuni's don't is a very poor throttle return spring -In the Webers it's a short little spring tucked away behind a plate at the back of the carby. The first thing you do for just about any application is take that spring out and throw it away, as they have a very common tendency to break and sometimes jam the throttle open. External springs were the way to go for all Webers of that type. I can't remember how the Mikuni's worked, but I think it was a better arrangement.

See?
I no forget!

[sillycar chick]

I am having more problems (the last problem was found to be the new air filters )
My hyrbid with the 45 webers is making a high pitched noise, sounds almost like a belt related noise, but its not (have started without belt and noise is still there). It sounds like its coming from the webers or manifold but i havent had time to have a decent look because uni is flat out at the moment Also noticed an intake manifold stud (from the head) is missing, have never noticed it before so dont know if its a new thing or not

Any light-shedding would be much appreciated

[jeffro ra28]

i dare say your missing stud from the intake is your vacum leak that is causing the high pitched noise.

[sillycar chick]

Yes me thinks that was it, just scouting around for ideas since I dont know if its always been like that since i bought the car

[Starfire]

I have two sets of Solex carbies here - one from a 2TG and one from an 18RG. I am building up a fairly decent 2TG with a 3T crank and 89mm pistons, which will take it out to 2L with 11:1 compression or so.

Knowing that any wayI go about it, I'll have to have them set up and tuned properly, which set of carbies would be a better starting point for my 2TG? I know that the 2TG ones fit without modification and the linkages are fine, and the 18RG units appear to have extra 'emissions garbage' on them, which is never good from a performance standpoint, but the 18RG is already a 2L, so I would assume that the tune should be in the ball park for my engine...

Which way should I go? or should I just sell the lot of them and buy some weber 45s?

Cheers,
Terry

[Rodger]

Gees why go 45 Webers? All they will give you is top end air volume and probably only improve your combo above 7000rpm. Then you would have to chase linkages.

Anyway my bias aside.

Use the pair of Solexes off the 2T-G (S5 type) as they have the inner sleeve which can be an option to remove to get more top end air volume but maintain good low end air speed.

All jets except the Pump Jets are interchangable between both types. Compare the two sets of jets and use the bigger numbered Pilot, Air and Main Jets. This will be the easiest and best starting point.

The Outer Venturis (chokes) are not interchangable so start with what is in the 2T-G set they are either #28 (too small), #30 (a bit small), or #32 (about right). All will however be safe and should provide good drivability.

Then we can sort out a better combo once you have run on the dyno. Probably go up in Air Jet and inner Venturi size and may tweak the fixed Pilot Air size.

Regards

Rodger

[Starfire]

As usual Rodger comes through with the goods. +rep

I'm sure I'll be chasing some parts from you in the near future. Given the quality of the linkage set you made up for Jordan's 4AGE, I'm sure you can help me out!

[Turdinator]

I have two sets of Solex carbies here - one from a 2TG and one from an 18RG. I am building up a fairly decent 2TG with a 3T crank and 89mm pistons, which will take it out to 2L with 11:1 compression or so.

Knowing that any wayI go about it, I'll have to have them set up and tuned properly, which set of carbies would be a better starting point for my 2TG? I know that the 2TG ones fit without modification and the linkages are fine, and the 18RG units appear to have extra 'emissions garbage' on them, which is never good from a performance standpoint, but the 18RG is already a 2L, so I would assume that the tune should be in the ball park for my engine...

Which way should I go? or should I just sell the lot of them and buy some weber 45s?

Cheers,
Terry

I don't want to contradict Rodger as the man definitely knows his stuff but these are my thoughts based on my own experience with hybrids.

Are you sticking with the standard cams? If your going to some wilder ones (i assume you are based on you comp ratio) I'd recommend going to larger than 32mm choke if you can. I would have thought at least 34mm maybe even 36mm.

I have 36mm in my hybrid and the car is still very easy to drive and its only stroked not bored. Shelldrake ran 34mm in his old hybrid with a similar setup to mine and it was a piece of cake to drive but felt restricted above 5500rpm. I have 284deg cams and shelldrake ran 302int and 290ex (from memory.)

But i guess it comes down to driving style. I enjoy the strong mid and high from the 36mms and just drive a little gently below 2000rpm. The 34mms were fine from idle.

[Rodger]

No contradictions here Turdinator. I agree with what you are saying. It will come down to Starfire's cam choice.

Stock cams run out of puff at around 5200rpm and the smaller #32 outer Venturis are a good match to that.

Regards

Rodger

[joey]

Having some trouble with the solexs on my new engine now (2tg, with big cams and lightned flywheel) It idles fine and from about 4000rpm onwards it purrs like a kitten, but from 0-4000rpm it stutter very badly. i got my carbie guy to look at it and he says it is running rich even though he has put some smaller jets in, which is causing it to flood around that mid-range, i agree aswell because after only minuites of running the engine with some new spark plugs i pulled them out again and they are all black. Now he reccomends sourcing some smaller jets as this is most likely the problem and he is going to give me a list of what sizes he needs when i pick up the car this afteroon so he can have a play around with it and get it running nicely..... anyone have any ideas as to what the problem might be if not the jets which were fine on my 3t and never had a problem with? Im quite annoyed as i just want to get it runing right so i can cruise and enjoy my new engine!
Cheers, Joeyu

[mike1980ra40]

check the idle mixture screws, mine did the same thing. tips of the screws might have rounded off, or, even broken off in the worst case.

[joey]

He said the idle screws were too large and put them down a couple of sizes, seemed to do the trick as it idles nicely now, so shouldnt be the idle screws.

Update:
Picked up the car before and was having a good chat to him. He believes the carbies are getting too much fuel and they can't handle it so i have to go down in jet sizes or either the engine cannot handle that much fuel thinking its something mechanical. When cold he just said to start it up but when it's warm i should take of the accelerator pump link arm as it seems to help with the stuttering a fair bit, and i must admit that it does. The engine doesn't seem do have that much power either, it seems just to have have a smidgen more than what my 3t had, before i gave it in to him when it was running rough it seemed to have that bit more power up top aswell
The jets that are in the carbies now:
Main Jet = 130 (the reading is taken from the bottom of the jet correct?)
Main air jet = 150
Pilot jet = 55
Pump jet = ? (not sure how to get it out without fcking it up)
He wants me to get some:
- smaller than 40 pump jets
- smaller than 130 main jets
- bigger than 150 main air jets
So he can have a muck around with the different sizes and drill them out if need be to try and stop the stuttering.

My question is that the jetting i have in there curerently is quite close to the typical toyota jetting, so would the cams or electronic fuel pump and regulator possibly be making it pump too much fuel and not being able to burn it? Just throwing an idea out there. Also would going smaller with the jetting reduce the performace?
Cheers, Joey

[mike1980ra40]

Is there a really loud and noticeable hissing sound when engine is idling?