[SuziBlu]

Does anyone know of a dyno man who is a weber specalist in SA ?

I have my DCOE webers on, makes her go like a shower of shit, serious power upgrade over the 38/38, got everything in place, just need someone who knows webers, doesn't have to be dyno.

[Marko_SJ]

SuziBlu wrote:

Does anyone know of a dyno man who is a weber specalist in SA ?

I have my DCOE webers on, makes her go like a shower of shit, serious power upgrade over the 38/38, got everything in place, just need someone who knows webers, doesn't have to be dyno.

Have you had a go at it? how in depth are DCOE's?

Sorry I can't help.

[SuziBlu]

Yea, had them on a month or so now, I have them running as good as I can, they make my toy go like a bat out of hell, but, the idle circut needs work, maybe jets, maybe emulsion tube, not sure.
I think the chokes are to small, my engine is reasonably modified and so by rights should be considered to be bigger than a 1.6l, chokes for a 1.6 are around 32mm, mine are 30mm, not much in it, but but everything I read tells me I need 34mm chokes

All signs say she is running too rich at low revs, ie, very black plugs, but symptoms say she is running lean, out of my realm.

at 1,500 rpm she will handle 5th well, but a slight throttle increase and she stumbles bad, put the foot in an off she goes, so im stumped.

[JrZook]

SuziBlu wrote:

All signs say she is running too rich at low revs, ie, very black plugs, but symptoms say she is running lean, out of my realm.

Do yourself a favor a buy/install a wideband O2 sensor/gauge into your exhaust. They usually sell for around $200-250ish. They are a nice little tuning tool.

[Marko_SJ]

SuziBlu wrote:

Yea, had them on a month or so now, I have them running as good as I can, they make my toy go like a bat out of hell, but, the idle circut needs work, maybe jets, maybe emulsion tube, not sure.
I think the chokes are to small, my engine is reasonably modified and so by rights should be considered to be bigger than a 1.6l, chokes for a 1.6 are around 32mm, mine are 30mm, not much in it, but but everything I read tells me I need 34mm chokes

All signs say she is running too rich at low revs, ie, very black plugs, but symptoms say she is running lean, out of my realm.

at 1,500 rpm she will handle 5th well, but a slight throttle increase and she stumbles bad, put the foot in an off she goes, so im stumped.

Again, no experience with DCOEs just generic carb experience.

Jrzook has said what I was going to say

This link here: http://cnx.org/contents/a0a6da11-6437-4 ... _of_Weber_

is telling me that your idle jets are probably the culprit.

Quote:

Idle jets (Figure and Figure) cause a lot of confusion; although their name suggests that they govern the idle mixture, this is not true. The idle mixture is actually metered by the idle volume screws (56 in Figure) mounted on top of each barrel. The function of the idle jet is to control the progression between closed throttle and the main jet circuit. As such it is important to smooth progression between closed throttle and acceleration and for part throttle driving. If this circuit is too weak then the engine will stutter or nosedive when opening the throttle, too rich and the engine will hunt and surge especially when hot.

I'd experiment with different idle jet sizes first if small throttle openings are the problem.

[TEKNO]

SuziBlu wrote:

Does anyone know of a dyno man who is a weber specalist in SA ?

I have my DCOE webers on, makes her go like a shower of shit, serious power upgrade over the 38/38, got everything in place, just need someone who knows webers, doesn't have to be dyno.

G,day Suziblu,you could try Classic Performance at Hackham...they did my 1.8 conversion and they did an awesome job. They also have a Dyno if you should require it mate. Ashley runs the place and he really knows his stuff so he may know how to tune carbys???? They have some impressive cars come through that place
Phone 8384 2899
Good luck

[SuziBlu]

Thanks Tekno.

[JrZook]

Be interesting to see what numbers it pulls

[SuziBlu]

Jr, from the seat of my pants, and I know that is not good, it is a serious upgrade to the 38/38s I had on previous.
I talked to Tighe a lot, he asked lots of questions of my toy, weight, ignition, carbs, head work, tyre size, gearing, driving style, what im after etc,

This was how he came up with the cam, I put the big carbs on, gave it an initial tune, took it for a run, an thought, omfg this is lethal, far above the 38s, tuned it up an down hill, doing times, same run, top speed reached etc. by the speedo, 130ks and floor it, you can feel her pull away.

I have taken the tuning as far as I can, and now its time to get someone who really knows webers onto her.

What power she has, no idea, but basically what she is set up for, as requested from cam, potter along, foot flat WOT and launch. 1st is basically useless, 2nd is very gentle with throttle or wheel spin (33" mickey tompson baja claws at 4psi)

From 1,500rpm in 5th all the way is fine, 3rd, 2,000 an floor it in the sand is near instant wheel spin and away like a bat out of hell, im very happy.

[Gwagensteve]

JrZook wrote:

Do yourself a favor a buy/install a wideband O2 sensor/gauge into your exhaust. They usually sell for around $200-250ish. They are a nice little tuning tool.

[SuziBlu]

Guys, looked in ebay for a 02 sensor, anything from reasonably cheap to quite expensive, whats good or bad.

Im told, once you have your webers set up properly, never touch, do i need a indash monitor, or get one that I shove up the exhaust, and get printouts of data, tune that way. ?

I can get a data printout off a mate, not a cost issue, but a value point.

[Gwagensteve]

If you're convinced you won't ever need to touch it again then just get a temporary one up the exhaust, so long as you have enough straight pipe to get the probe deep enough into the tailpipe.

It seems that people with carbs are always playing with them though, so maybe a permanent install is preferable, and will eliminate any issues with ambient air mixing in the tailpipe.

[SuziBlu]

lol Steve, the second part is me to a T, never happy, permanent it is.

Do you have thoughts on different brands, is one better than the other, do you get what you pay for, or are they all pretty much the same ?

[Gwagensteve]

It's really all about the sensor- which I think is generally a Bosch unit. Display is really just preference.
Make sure it's definitely wideband though.

[SuziBlu]

ahh cool.

Teach me a bit, wideband, why, what is it, more gas types or what ?

[Gwagensteve]

Narrow band just tells you rich or lean. Wide band provides the actual ratio.

[SuziBlu]

cool, wide band it is.

[JrZook]

I'm currently using an AEM wideband unit
http://www.ebay.com/itm/NEW-AEM-30-4110 ... 1571397731
Works quite well! I would weld the o2 bung in where all your primary headers merge to get the most accurate reading. Can always take the sensor out and put a blanking plug in there afterwards.

[SuziBlu]

Was thinking about this yesterday, how will this help with multiple carbs, stupid but, wouldnt you want 4 bungs, one in each primary so as to get individual readings, i throat per cylinder, each throat seperatly tunable, so, wouldnt 4 holes, 1 in each primary be best ?

[Gwagensteve]

In short you're overthinking it. You'll drive yourself mad with tiny inconsistencies. Surely all four carbs have the same jets/vacuum/fuel pressure?

[SuziBlu]

True Steve, but fine tuning ?

I drive myself mad with this machine now lol.

Im working with Weber to fine tune it now, top end seems fine, bottom end is a worry, runs so rich at idle you can see black smoke at the exhaust, but pops back thru the carbs like too lean.

Im only getting about 75% throttle, its a pisser, how do I increase my throttle cable travel ?

[Gwagensteve]

You can't work out how to increase throttle cable travel but your asking about fine tuning a quad throttle body carby based on lambda readings on each cylinder? You're definitely overthinking it. If you had significantly different A/F across the cylinders you have a major problem. All carbs should be jetted the same and see basically the same conditions. Differneces should be only due to temperature changes and they're going to change constantly.

If you want to drive yourself mad go right ahead and buy four bungs.

The irony is strong though- EFI cars use lambda to trim fuelling all the time

[JrZook]

Gwagensteve wrote:

You're definitely overthinking it. If you had significantly different A/F across the cylinders you have a major problem. All carbs should be jetted the same and see basically the same conditions. Differneces should be only due to temperature changes and they're going to change constantly.

If you want to drive yourself mad go right ahead and buy four bungs.

This!

Do not worry about ultra fine tuning individual cylinders or you will drive yourself mad! Place the bung where the pipes merge to get the average AFR reading over all cylinders. This is what 99.9% of EFI cars do. Keep all the jets/emulsion tubes etc the same over all the carbs while tuning and you will be fine.

[neofitou]

SuziBlu wrote:

True Steve, but fine tuning ?
Im only getting about 75% throttle, its a pisser, how do I increase my throttle cable travel ?

Maybe should be able to work this out if your mucking around with carbs....?

Reduce the diameter of the throttle cable wheel or the length of the throttle linkage arm (whichever applies) so the same amount of cable throw turns the throttle more.

[SuziBlu]

Steve, can't see any relationship between working out how to get 4" of travel out of a cable that only has 3" of travel, and tuning a car.

Neo, thats a maybe, but short travel throttle over very rough country makes for nasty throttle on/off all the time.

[Gwagensteve]

I can. One is simple problem solving. The other requires an understanding of the relationship between a number of variables. In surprised you've gone to the point of discussing your problem with Weber without gaining full throttle travel before you start.

Just sayin'

[SuziBlu]

They know, throttle opening to stop, has nothing to do with idle, I thought you would have known that.

[Gwagensteve]

I couldn't care less about carbies, but it doesn't matter for my point to be valid. So you're rich under idle and who knows what in the mid range and you can't get the last 25% of throttle travel so who knows what's going to happen there.

[SuziBlu]

She pulls to 6,000rpm well, gets there fast, plugs are a lovely golden brown while playing, so 2 of the 3 circuts are pretty much spot on as I see it. its just idle that is running rich.

I would suggest that the last 25% percent of butterfly opening, by the way it gets to 6,000rpm so easily, but not beyond, is not a real issue, but one I would like to try and sort out.

[neofitou]

So increase the travel of the accelerator pedal.. That's the only thing you can do to get more travel from the accelerator pedal. Bend it out so it sits higher and move the stopper. I think that would be shit, but it's the only way you are going to get what you are asking.