243 replies to this topic

[Brian Pascoe]

Hi James, Well its taken some time,but I would like to thank you and Franck for all that you guys have done,much appreciated.Also the 3mm hole in the idle jet,if it was continued up into the idle jet holder would that be of any advantage. 

Brian 

[natcamp10]

Fantastic thread guys

[jd lj]

Hi James, Well its taken some time,but I would like to thank you and Franck for all that you guys have done,much appreciated.Also the 3mm hole in the idle jet,if it was continued up into the idle jet holder would that be of any advantage. 
Brian 

Hi Brian,
We're happy to help. I'm glad that our guidance has been helpful to you.

As for drilling the hole in the idle jet holders to 3mm I don't currently have an answer on that or know if that's been tested yet. I checked one yesterday and that hole measures around 2.5-2.6mm. Feel free to experiment with it and report back with the results :-). What we've done here so far is all relatively new and further enhancements may still be possible, although Keith has worked through everything very thoroughly, there's not going to be many stones left unturned.

You still potentially have further gains to be had by tweaking the idle jets as I described by adjusting the fuel or air bleed holes depending on your requirements.

Keep in mind that your 45dcoe13's only have two progression holes so your progression circuit will have a slightly shorter duration than if you had an additional hole further upstream. If you had a stronger manifold vacuum level then this may not be of concern. There'll be a point where some minor compromises need to be made, by this time if you weren't looking at the AFR reading you'd probably be happy with the tractability. The gauges can make us overly fussy sometimes.

Using ram tubes would also be beneficial.


Nathan,
Feel free to ask any questions as I'm sure some of this may be confusing when trying to take it all in in one go. Most of this thread is very different to what's ever been written about dcoe's in the pastto the best of my knowledge atleast, but this method is all scientifically tested. Before now tuning dcoe's has been thought about in a mechanic's mindset which no offence to anyone has lacked the scientific understanding that's been required to achieve what Keith has spent the last several years doing in his retirement.

James D

[jd lj]

So as I mentioned above that ram tubes would be beneficial. As I'm sure you have heard that ram tubes create the Bernoulli effect with the air speeding up as it enters the ram tubes due to the I.D (internal diameter) of the tubes being 45mm (on a 45dcoe) compared to the lip of the ram tubes being 65mm IIRC. However if you have ram tubes that just bolt onto the face of the carbs and don't slide into the throat and butt into the auxiliary venturis then once the air enters the carb throat after leaving the ram tubes then the air is now in a 48mm I.D area which means that it'll slow down slightly.

Now this next part is where this gets more important. The front tip of the auxiliary venturis is positioned in the area of the carb throat that measures 48mm I.D but if you have ram tubes that insert into the throat of the carbs then this same position now measures 45mm I.D and the air is at a faster speed when it enters the auxiliary venturis (AV's). The main circuit is activated when the air flowing through the centre of the AV's is travelling fast enough to create a vacuum on the emulsion tube well. The tail end of the centre of the AV's is also located at the narrowest point of the chokes where the air speed is also at its greatest. Some people bore the chokes out to larger diameters to suit their needs but care must be taken not to simply bore straight through as keeping the narrowest point in line with the tail end of the AV's will help draw more air though the AV's. The faster that the air flows through the AV's the earlier the main circuit will tip in.

I can't remember if I've already mentioned this when I talked about cleaning up all the casting ridges from the AV's or not, so forgive me if I'm repeating myself. With the front tip of the AV's if you look closely you'll see that there's a flat section before the centre tapers inwards. This is because they're made from two pieces. This flat is called the stagnation point. The air hitting the stagnation point can then flow either way. So I have machined mine so that the internal taper extends all the way to the outside of the centre tube section of the AV's. This in theory should mean that more of the air has to flow through the centre of the AV's. From memory I think that this effectively increases the diameter by 3mm. Whether or not this makes any noticeable difference I don't know but I've gone looking for any improvements possible.

Unfortunately there's not too many options available as far as air filters go for ram tubes, especially in LC/LJ Torana's with minimal clearances around the ram tubes. The stainless steel mesh screens don't filter particles fine enough and are surprisingly restrictive, they also disrupt the air flow into the ram tubes reducing their effectiveness. The sponge socks over the ram tubes suffer many of the same problems. This situation is why I made the air box for my car, the ram tubes are still used with my air box and there's an air filter in the front.

https://www.flickr.c...2478@N02/04c429

https://www.flickr.c...2478@N02/z9qP9k

James D

[jd lj]

Having now thought about this further I should be able to measure the difference in vacuum levels on the emulsion tube well of the above variations using my vacuum gauge, assuming that it reads in a fine enough scale. I'll have to see what hoses and fittings I can cobble together to do the job. Don't hold your breath waiting for results I'm in the midst of other jobs around the house atm.

James D

[jd lj]

Hi James, Well its taken some time,but I would like to thank you and Franck for all that you guys have done,much appreciated.Also the 3mm hole in the idle jet,if it was continued up into the idle jet holder would that be of any advantage. 
Brian 

I got you an answer on your question about drilling the hole in the idle jet holders, Keith has already tried it and says that there nothing to be gained or lost by doing so.

James D

[natcamp10]

Hey gents
I’m about to order fuel air ratio gauge and so I can jump onto this thread when I get home , there are a couple of selections on eBay , what do you recommend , can I buy a guage by itself and wire in any o2 sensor into it ? Or should I buy the guage with sensor supplied , there is a big price difference , I too have had some dramas setting up my Weber’s , after many hours of researching I worked out the my chokes were to big and my jets were to big , my settup was 40 mm chokes with 155 main jets with f8 idle jets and f2 emulsion tubes , I changed the chokes down to 36mm with 150 mains which made a massive improvement with a stumble into the secondaries , I also went to the f950 into the idle curcuit, I didn’t do it with as gas analyser but did it by looking at the burn on the plugs . I want to revisit this so I’m about to order the gauge setup so I can give some readings At problem rpm range Although it’s a massive improvement it’s still not not perfect , I’m using the 45s with three progression holes running on a red 202 stage 3 yt 9 port head with ram tubes as well . Gents I m away at work til the 10th , i will post more detailed info then ,

[jd lj]

As far as choosing an AFR gauge/meter it depends if you want the advantage of datalogging. Previously I've been using the Innovate lm-2 and it's a great tool with the software to analyse your data after recording runs. However this unit is not intended for being permanently fitted to the car and will have multiple cables running to it. It also has a few gremlins that get a bit annoying. This company has recently been bought by Autometer so hopefully they can sort out any issues it has.

I'm literally sitting here opening up the box containing my new AEM FAIL-SAFE WIDEBAND GAUGE 30-4900. This is going to be a permanent fixture in my car. This gauge measures AFR/lambda, vacuum/ boost and has an internal datalogger. You can also set either min or max limits for the AFR or boost that when reached will either set of an alarm / flashing warning lights or can also be set to stop the ignition from firing etc. The fail-safe gauge also has annaliticle software like the Innovate lm-2's so you don't have to try to read the gauge whilst driving.

AEM and many other brands have gauges that just read the AFR and don't have datalogging capabilities.

PLX Device's have an interesting gauge that can read up to 16 different inputs depending on how you set it up, this requires additional modules to be added in line. An interesting feature is that it also has a WiFi adapter so that you can use your phone as the gauge and this means that if you're keeping everything original you don't have to fit a gauge at all. Unfortunately PLX Device's don't offer datalogging and a third party unit is required to do that.

As I haven't actually used my new AFR gauge yet I'm in no position to comment on its ease of use or quality yet. But after reading up on these units the feedback has been much better than the lm-2's.

Nathan, since your car is running the first thing that you need to do is measure your manifold vacuum level at idle. Do this via the brake vacuum hose but you'll need a one way check valve fitted to stop the needle flickering wildly due to only reading off one cylinder. I'm guessing that you're vacuum may be below 18Hg. I know that your planning to build a new engine so what works now with this motor may vary from what the new one requires. My tip for you will be to replace your f2 emulsion tubes for either O6 or VF tubes as I mentioned earlier in this thread.


James D

These emulsion tubes are available here....
https://www.webstore..._id,other_items

[natcamp10]

Hey James
I checked out the gauges you recommend
It’s a shame that on the plc unit you have to buy another module to data log , I don’t really want to fix a permanent guage to the car either so I’m looking at the I’m-2 basic kit , for a weekend worrier would this one do the job I need it to effectively trouble shoot with ?
I will run the vacuum test as soon as I get hm and post the results
And yeah got plans for a new engine build set to start in a couple of months but would like to play around with the old engine to fine tune my diagnostics

[jd lj]

Nathan,
Yes the lm-2 will do everything you'll require to get stuck into your tuning. It needs a SD card to record onto but not all of them are in the correct format, so you might have to try a few. I can't remember atm which type you need but I'll get back to you with that.

James

[jd lj]

If you want to log rpm with the lm-2 (which is highly recommended) you'll also need the anologe input cable which will probably be about another $45-50. The rpm signal is prone to EMI and resistance type spark plugs will help with that.

[natcamp10]

Thanks James just purchased the full kit

[natcamp10]

Brian,
Have you fitted smaller chokes and AV's yet?
What main jets and air correctors are you currently using? Try increasing the air correctors as with the VF tubes doing so increases how much fuel is getting drawn through.

Don't despair, your in capable hands. If you give Keith the appropriate information he'll guide you through the tuning process.

James

Gents
What are you referring to when you say vf tubes and av”s ??

[jd lj]

The AV's refers to the auxiliary venturis and the VF tubes are the latest type of emulsion tubes. O6 tubes are another type of emulsion tubes. Both are available via the link to the "Webstore" from Keith Franck that I posted yesterday or so. He also has hypojets and "W" (weak manifold vacuum) jets which are both special types of idle jets.

I'm pretty sure that in earlier posts I've given definitions of all these abbreviations as I go. As I said there's a lot to take in and some of it you'll likely have to read multiple times to understand what it means. When I was learning all this I had to reread lots of things to fully get my head around it. What's written in this thread you won't find in any books about webers as to the best of my knowledge no one has taken this approach to them before. But trust me the results will speak for themselves.

James D

[jd lj]

I was talking to a guy recently who has a triple weber LJ who was told by multiple "professional tuners" that you can't get the mid range hesitation out of dcoe's and that's why they are for race cars not street cars. This is just a case of them not understanding the physics involved in dcoe's and how to make them work. Like so many other people he'd taken his car somewhere to get tuned and it came back worse. He was then referred to me and we worked through the problems over the phone with him doing the work under my instruction. The car is apparently running much better now than it was after paying hundreds for someone else to give it a good flogging and tell him they tuned it. He still has more to do in the future when he's prepared to put some decent emulsion tubes in instead of the f2's which are the centre of his problem.

When I first bought my car I didn't know how to tune webers and was refered to a so called guru to get it done, when I got it back it still had a massive hesitation when accelerating from 2500 rpm's, it was like it was tripping over itself before it'd get moving. The frustration of this led me on a path to search for a remedy and over many years I've learnt what I'm now sharing here. My timing was fortunate because if I'd started earlier then the answers wouldn't have been discovered by Keith Franck yet. I've been following his progress almost daily for several years now as he's tirelessly worked through these issues that dcoe's have.

I've heard other people have had to learn to drive to try to avoid the dcoe's problems but with the right knowledge this isn't necessary either.

Whatever problem your dcoe's have whether it's an off idle stumble, mid range flat spot, surging or lazy idle syndrome or whatever else then with the right components it can be resolved.

James D

[natcamp10]

Hey james
I would like to thankyou for sharing your knowledge on this subject , ive been searching for stuff like this for a while , ive ordered the lm-2 afr meter and would like to refine my weber setup, i keep reading this thread over and over and learning a little more plus going back over the manual . Really looking forward to posting some data so you can have a look , altho i got the hestation in the rpm around 2500 Where it transitions to the mains is pretty good now it sometimes plays up and im not sure why , like you said above its how you drive it , then engine came out of a track car but like it says within thw thread 40 mm chokes are too big ..
i will have some good date and a full spec list to post soon ,i also have all my old bits as well , hopefully the lm-2 will arrive next week
I do have one question while i waiting to get home
Are you suppost to use vacum advance with webers , ive heard not but no one can tell me why , im running a blue motor electronic dizzy with no vacum advance on it and i do get a bit of pre ingnition but nothing like when i first started . When i first got the motor i found the wieghts had been removed and it was locked and running heaps of advance , i changed it back to a standard which helped alot
You guys talked about running alot of advance when running webers but when i advance my ingition up it gets woarse.
Im in and out of this thread on my breaks and you may of covered this but would like to understand more , i know with cammed motors you have to graph the dizzy but in my case atm im sure ive only got a mild grind on it , i do have a stage 2 hyd cam i was gonna put in this motor just for mucking around and cause i can Plus im gonna do this when i open it up to have a look inside , im doing this because i suspect alot of the things in this motor will be a good starting point for the engine build im going to start late this year . Its a strong motor and revs hard without virbration issues that read alot about
Cheers gotta get back to work

[jd lj]

To be honest my knowledge of ignition systems isn't as good as I'd like it to be so perhaps someone who knows this topic better than myself can give you a better answer than I can. My own ignition system hasn't given me any need to change anything and learn the ins and outs of the matter.

However...
The carburettors are just a simple means to control the air /mixture entering the engine and the dizzy doesn't really know what type of carbs you have but instead only knows how strong the vacuum signal is. This signal strength can vary greatly with different engine specs. What works on one engine won't necessarily be correct for another, you've got to set it up to suit your requirements.

The 45dcoe54 and 45dcoe56 were originally fitted to RT CHARGER'S and have a fitting for the vacuum advance built into them.

James D

[Brian Pascoe]

Hi James,

Here is the weber setup I now have on the 186.

Idle jets modified from 45F8's  to 50F8's with a 3mm hole counter bored and the F8 hole drilled into  the side lower down towards the bottom of the counter bore and the original hole soldered up.

Light fuel pump spring installed.

Accelerator pump jet 50.

VF Tubes

Needle and seat 175.

34 mm chokes.

AV's 4.5

Main Jets 155

Air Correctors 210.

With this setup I still have a very slight lean just off idle, the AFR goes from 12.5 to around 16 AFR then back to 12.5- 13.0. all the way to 6,000 in 2nd and 3rd gear.

What do you think is next on the list to try.

Brian

[jd lj]

Brian, I just went back and had a look at the picture of your set up and noticed that you have the balance tubes fitted joining the manifolds, is that the warnerford manifold I assume. Remove those balance tubes and plug the holes and try it again. The tube sections cast into each manifold do they join each individual runner of each manifold?

Your pump jets are still quite large, normally with your choke size I'd be using 40's on a street car and 45's on a race car. If the pump jets are too big then they can give you a false lean reading and a hesitation because they can momentarily flood the engine and the O2 sensor only reads burnt fuel and not liquid fuel so it'll give you a lean reading even though it was too rich.

If I use 45 pump jets in my car it's great for WOT from low rpm's but at smaller throttle openings it can give a brief hesitation for the above reason. So I use 40's (with 34mm chokes) with good results.

The pump shot can be varied in several ways as I've mentioned earlier in this thread, the primary adjustment that the pump jets themselves make is to control the volume per second of the shot (along with the spring tension having a say in this too). It'll also have an amount of control over the duration of the shot by its size controlling how much of the total volume of the shot passes through it at within a given period of time.

James D

[jd lj]

Once you remove and plug those balance tubes could you retest your manifold vacuum level? I'm just curious if it'll change it at all.

James D

[Brian Pascoe]

James,I will do as you say and get back to you.

Brian

[jd lj]

Brian, the other thing that I may have forgotten to mention is that with your modified idle jets using a smaller air bleed hole will make the mixture richer coming off idle and leaner at the main circuit tip-in
A larger air bleed will have the opposite effect. So it's a balancing act to find the combination that works best for you at both ends of the spectrum.

James D

[Brian Pascoe]

Hi James,I haven't had a chance to redo the vacuum test yet,but I drilled the idle jet out to .55mm .It is now 55F8. I reset the idle mixture at 900 rpm in neutral  to 12.5.I then took it for a road test. The AFR in 2,3,4 gear without any pedal or just slightly shows 9.5 AFR.As I slowly increase throttle the AFR goes to the high side of 14 AFR.Then it drops back and floats around 11 to 14 AFR under moderate acceleration.

Brian

[jd lj]

Was this with the balance tubes removed from your manifold or not yet. It sounds like the 50f8 modified idle jet works better for you. I'd suggest trying the 50idle jets but with a slightly smaller air bleed hole to richen the mixture coming off idle, this will also lean it out slightly as you reach tip-in so as I've said it's a balancing act getting the best combination at both ends of the spectrum.

James D

[Brian Pascoe]

James, I forgot to mention that the idle mixture screws are only out 1/4 of a turn and I still haven't removed  the balance tubes.I will do as you said in the above.

Brian