243 replies to this topic

[jd lj]

Hi Brian,
Sorry for the late reply.

I'm glad that you're happy with the improvement of the tune so far. I'm sure that it's a very different car to drive than what it was prior to all this.

It sounds like you're approaching the point where if you improve one area it'll be at the sacrifice of another. This is basically why carburettors were phased out and replaced by fuel injection. There's only so much versatility that a carburettor with only a few circuits can provide.

To improve your lag around 2800 rpm's I expect that having a third progression hole on each barrel would be beneficial as that will extend the dynamic range of the idle circuit. On engines with lower manifold vacuum more progression holes are required to provide a smoother transition into the main circuit, whereas engines with a higher manifold vacuum can get away with fewer progression holes.

As you can see from your description the mixture can vary quite noticeably at the same rpm's depending upon the driving conditions,load and throttle opening.
If you wanted to lean out the hwy cruise mixture slightly a bigger air corrector may help but then you'd likely need to increase the size of the main jets to provide the appropriate mixture at WOT/high rpm's. Alternatively you could try using something like 35mm or 36mm chokes to lean it out slightly but doing so will lose a small amount of low rpm's torque and reduce the vacuum signal acting on the emulsion tube well and could therefore slightly increase the slight lag that you have. If you need 35mm chokes let me know and I'll see if I can get hold of some as these are not normally readily available.

As you can see if you adjust one aspect it may be at the compromise of another, so eventually you'll need to decide on what your priorities are.

Personally I think that adding an additional progression hole would be a good place to start.

I can't remember which version of the VF tubes your using, are they the std VF tubes or some EVF tubes?

James D

[Brian Pascoe]

Hi James, They are the std VF tubes in it at the moment.What is difference with the EVF tubes.

Brian

[jd lj]

The EVF tubes supply more fuel at tip-in too help eliminate the mid range hesitation.

[Brian Pascoe]

Hi James,Sorry I have'nt been in contact for a while as my 186 has been performing very well.But now I noticed when I came back from a drive,I noticed fuel dripping from all 3 carbies.It was dripping from where I  have the soft mount sections installed. The fuel reg is set at 3psi. Have you any suggestions on the possible cause.

[jd lj]

Hi Brian,
I'm glad to hear that it's been running well.

The first thing that I'd check is that the fuel levels are set to 25mm,they shouldn't have changed but just confirm it anyway. Also look down the throats as the engine is running using a mirror or the camera on your phone to make sure that there's no excess fuel dripping from the auxiliary ventruis at idle. This can be a symptom of worn needle and seats, floats with holes or floats getting caught on the inside of the float bowl or incorrectly set fuel levels. It's unlikely for these faults to occur on all three carbs at once though.

The most likely problem is that the softmounts have compression set and aren't sealing effectively. Over time the rubber compresses and loses some of its rebound, the rubber spacers on the mounting studs also deteriorate and don't apply pressure correctly.

My advice is to discard the softmounts and solid mount the carbs. I can supply you with bakerlite dcoe spacers that I make on the cnc for this purpose. They require a gasket each side of the bakerlite spacers and will put an end to any leaks from the softmounts. I have my own car and several others set up this way and this has given great results. It's a myth about needing softmounts to stop the fuel from frothing as I tested this extensively myself. RT Charger's had their dcoe's solid mounted from the factory without a problem too.

My bakerlite spacers are 7-8mm thick which is similar to the softmounts thickness. I can make them for whatever throat size is required i.e. 40,42,45,48,etc. But you'll use 45's. The bakerlite spacers are $30 each, you'll need 3 plus the gaskets.

I also have made batches of my DCOE return spring kits and my throttle cable wheels for triple or twin carburetor linkages, these are listed on Gumtree but I'll add a link later. Plus I'm now also offering my dcoe rebuild and restoration services.

James D

[jd lj]

Here's the link to the throttle cable wheels and if you scroll down you'll be able to link from there to my other listings for dcoe parts.

https://www.gumtree....-su-/1225885527

[RallyRed]

Sorry guys, quick thread hijack ( save starting another one)
Dont like running with no filters on this car...Nothing wrong with just cutting off the ends so filters will fit James?
Ta

Attached Files

•  rps20190818_152248.jpg   188.01K   4 downloads
•  rps20190818_152305.jpg   178.37K   5 downloads

[RallyRed]

yes Wayne, I must agree. It does grow on you.
End of thread steal.

Attached Files

•  rps20190818_164654.jpg   190.05K   9 downloads

[jd lj]

Hi Col,
You're welcome to join in on the thread with any WEBER related questions etc, the more people that we can help the better.

I know where you are coming from with not running air filters on your engine. I wonder why people spend such big dollars on building their engines and then run no air filters. This is why I made the air box for my car. I own the mould for it and I'm happy to make more. I designed it to suit my Seton manifolds but it may be suitable for others also as they share almost identical carb spacings, the backing plate would need to be drilled to suit which ever manifold is being used.

Cutting the ends off the ram tubes will make them not function correctly and actually reduce the air flow.

James D

[RallyRed]

Ta James...I suspected that it may have affected the flow a little. I guess in the short term ( this Friday, first drive , muck around day), it may just run a little richer? i.e less air/ same fuel?.
Or is it more of a case of less air/velocity = less fuel venturied anyway, so same AFR, just less power?.
Sorry if I have that all ballsed up.

[RallyRed]

p.s. they are Dellortos

[jd lj]

Yes, less airflow will mean that less fuel is drawn out of the auxiliary ventruis, the mixture probably wouldn't vary much, you may just lose some power.

I'd noticed that they are dellorto's, they share the same bolt pattern at both front and back as Webers so any bolt on filters etc should be interchangeable. Are they 45's?

I'm going to make another batch of my dcoe bakerlite spacers so if anyone else wants some let me know and I'll make them at the same time.

James D

[RallyRed]

Ta James,  we are going to run the car this Friday, so will see how it goes.

 

Stay tuned re the spacers.

 

Col

[jd lj]

I've just finished making the bakerlite spacers to suit 45 dcoe's and dhla's. One set is sold but I have two more sets available if anyone is interested. These will come supplied with gaskets and flat washers so that you have everything required.

JD

[jd lj]

Here's a link to the bakerlite spacers that I make.

https://www.gumtree....orto/1227152399

James D

[natcamp10]

Hi James
Thread update
I’ve got a mild 202 running yellow trerra hc head with a dynotec cm205d cam ready to play around with
Weber specs are
36mm chokes with options to change to 34mm
06 tubes on six holes from Kieth with 145 air correctors
50f48 idle jets
What would the float level measurement be on 45mm 152g Weber’s using plastic float set up is it still 25mm?

Regards
Nathan

Edited by natcamp10, 03 September 2019 - 07:33 PM.

[jd lj]

Yes, regardless of the model of dcoe used set the fuel level at 25mm down from where the emulsion tubes and idle jets screw into.

James D

[jd lj]

When setting the float on 45dcoe152 and 45dcoe152G's (or any model with plastic floats) measure the gap between the gasket and the end of the float furthest from the needle and seat and what I've found to work well on a few that I've set recently is a gap of 9.5mm. The lid needs to be held vertically with the needle and seat at the top. The tang between the floats should be resting on the ball of needle and seat but not pushing it in. Once this is done refit the lid and run the engine for a few minutes with the emulsion tubes removed to settle the fuel volume in the float bowl. Then turn off the engine and immediately measure the distance from the surface of where the emulsion tube screws into down to the fuel level. Always take the measurements from the rear emulsion tube well on each carb because the engine sits higher at the front than the back and this will mean that the two wells on a carb will get a different measurement. If you set the front well to 25mm then it has potential for the fuel to running down into the auxiliary ventruis passageway as the engine rocks a bit at idle with a big cam.

If you need to adjust the fuel level then for every mm that you adjust the float it'll change the fuel level by 1mm.

You can use drill bits to measure the gap between the gasket and floats.

I've seen some of the plastic floats that have been a bit twisted lately. They should be parallel to each other and at 90 degrees to the underside of the lid so that they don't bind and catch on the inside of the float bowl.

[jd lj]

Nathan,
As I discussed previously the 50f8 idle jets are likely to be too lean when using 45dcoe152's. I had someone else recently say that they read that 50f8 idle jets were most suitable for 202's. But this information doesn't take into account the model of dcoe being used.

50f8 idle jets can work ok with 45dcoe13 carbs which only have two progression holes, but other models of dcoe's have more progression holes of various sizes.

So as a starting point here's my suggestions for idle jet selection on 45dcoe carbs on Holden 202's. But remember that this is a guide only and each engine has it's individual needs.

45dcoe9 (with 2 progression holes) =50f8

Note, there's about 4 variations of the 45dcoe9's

45dcoe9 (with 3 progression holes, this model has welch plugs over the progression holes instead of the normal screw in covers) =50f12

45dcoe13 (2 progression holes) = 50f8.

45dcoe53-57 (3 progression holes) = 55f8.

45dcoe150 (3 progression holes) 55f8

45dcoe152 (3 progression holes) = 55f8.

45dcoe152G (4 progression holes) = 55f8-55f9.

Remember that this is a guide only and doesn't take into account the manifold vacuum level or other factors to a specific engine.

Nathan,
If you are still having any problems with the main circuit tip in hesitation it may pay to try using a 55f8 idle jet and see how it goes. If that isn't sufficient then I'll tell you how to adjust your O6 emulsion tubes to supply more fuel at tip in other than just opening all 6 holes. Did reducing the air corrector back down to the correct size for the number of bubbling holes being used help?

For anyone following along, Nathan is using O6 emulsion tubes which are far superior to the traditional f2 or f16 emulsion tubes. On the f2 and f16 tubes the bubbling holes are too high and aren't below the fuel level off 25mm, their holes are another 2mm higher at 23mm and therefore cannot produce the bubbles required to raise the fuel level in a timely manner and this is why everyone gets a hesitation at around 2500rpms.

The O6 tubes have the holes 27mm down which is 2mm below the fuel level and CAN produce the bubbles required to raise the fuel to eliminate the hesitations.

When using the O6 tubes you can adjust the richness of the main circuit at tip by opening or plugging up one or more of the 6 bubbling holes, a minimum of 1 must be left open though. More open bubbling holes means a richer main circuit tip in. The size of the air corrector used depends on how many holes are open. Using too big of an air corrector will lean out the tip in mixture. IIRC I've probably listed the correct size air corrector to used for each quantity of holes open on the O6 tubes, if it's not already there I'll add it later.

The O6 tubes tend to run a bit richer than f2 emulsion tubes and will likely require smaller main jets than what people have previously used with f2 tubes.

James D

[natcamp10]

Hi James
Cool 25mm on the back wells for the floats
I’ve got a set 55f8 idle jets , I will throw them them in 😀.
I have put the 145 air correctors in
Test drive will be this weekend I will keep ya posted
Nathan👍

[jd lj]

Here's the air corrector sizes to use with the O6 emulsion tubes which Nathan is using. Note that these sizes are irrelevant if you have f2 or f16 or any other std Weber emulsion tubes.

2 bubbling holes = 0.85 ac
3 bubbling holes = 100
4 bubbling holes =115
5 bubbling holes =130
6 bubbling holes =145.

The size of the air corrector varies depending on how many of the bubbling holes are open. This formula used the smallest air corrector which is capable of supplying just enough air and no more.

James D

[jd lj]

Back to the idle jet selection vs the model of dcoe for a moment. The reason that different models of dcoe's requiring different idle jets is due to the progression hole pattern and sizes. Any progression holes that are upstream of the throttle plates act as an air bleed to the idle/progression circuit. Ideally at idle the throttle plates should be positioned directly below the first progression hole. The rest of the progression holes are then exposed to manifold vacuum and will draw air up from the barrel which therefore leans out the circuit.

James D

[jd lj]

I'm planning on taking some of the Weber parts that I make up to toranafest on Sunday. So if anyone is interested in the bakerlite spacers, return spring brackets or throttle cable wheels let me know and we'll catch up.

James D