Weber conversion update

[Benjamin]

Hi all,

After a thorough analysis of the problem on the weekend I have come to the conclusion that the modifications as outlined on Ben Wight's website are not suitable for my particular carb.

That is not to say Ben's information is invalid, I still say it is the best resource around(!), however my model of carb doesn't allow fitment of a similar setup, here's why:

The carb Ben used is a DGAV (correct?), with the auto choke. My model is the DGV with manual choke. There appear to be slight differences between the two. The biggest difference being an additional mounting post the DGAV has in place of the bracket which holds the manual choke cable.

This post appears to be fundamental to the mounting of the modified bracket, therefore I cannot adopt this setup. The second difference centres around the choke actuation area, which I can't clearly make out.

Either way, I wish to retain the manual choke, no amount of modification to the cable pull bracket will make it fit

Instead I will be fabricating an alternate bracket which I think may work. I will get hold of a piece of 3mm steel, approx 200mm x 160mm, and mount that on top of the carb between it and the air cleaner, cutting a hole for the venturis and such.

The corner nearest the cable will have a tag, bent over the choke setup reaching down to hold the cable. The standard cable can be used, and the cable cam from the Niki can be flipped as shown in Ben's workshop.

I will need to design the tag right and put some thought into how I can make sure it won't bend. I doubt it will, but never can be too sure.

If anyone has some clues before I go down this track, I would appreciate. Someone has to have adapted a DGV before (not DGAV) so there must be other solutions to the problem.

Cheers

[GasGem]

I've fitted a DGV with mechanical choke before,
To make the accelerator cabe holder I used, a length of steel bar about 3 - 4 mm thick and about 15-20mm wide, drill a hole at one end big enough to fit over the carbi mount ing bolt closest to the accelerator cable.

Now then bend the bar in a vice until you get it to hole the accerator cable in place, requires some interesting bends but works well, then drill a hole at the end to fit the cable in and cut a small slot for the cable,


Cheers
Eggy

[Benjamin]

Well, I suppose that would work too. I had briefly considered that option but by the looks of it the nearest stud wasn't going to be long enough, leaving only a few coils of thread to bolt to. If I can get hold of a longer stud to suit it sounds a heck of a lot easier than routing out 3mm steel...

Thanx Eggy

[Ben Wight]

Your'e right Ben, I've only done the mod with DGAV's, to be honest, I dont think I've even seen a manual choke version.

The simplest way would be to ditch the choke, but obviously you want to keep it.

Both yours and Eggy's way would work, so get stuck into it. Once you've done one, you'll realise how easy it is.

Ben Wight

[PinkBitz]

yeah i say fuk the choke off all together. whats a few more mins warmin it up gonna cost.

[Benjamin]

True but even though mine is tuned reasonably well, she is fluffy on heavier throttle applications on cold mornings (with the choke off). My engine runs really cold (even with a decent thermostat) and after a couple of minutes of warming I have to be careful on intersections and the like.

The choke smooths the bottom end until up to a decent temp. A saying I have heard recently is: your carb mustn't be tuned properly if a choke is not necessary. It contradicts what you say Ben, I am now successfully confused. I think I will stand on the middle ground and leave the choke on.

Cheers and thanx

[Ben Wight]

I'm just going by my own experiences with tuning carbs, and that is after getting the thing tuned pretty right when the engine is warm, it also ran pretty well when the engine was cold. I then read this in a couple of tuning books about webers and dellorots, and thought it must be true as it backed up what I had already witnessed.

As far as the engineering side of things, if the engine is not warm enough to run on warm engine settings, it shouldn't really be loaded up or else premature wear will result.

Another point is that a cold engine requires more fuel for complete combustion due to a higher percentage of the fuel staying as a liquid instead of vapourising from the engine heat. I would also guesstimate that as the pistons have not reached their expanded size when cold, there will be less inlet manifold vacuum at idle, as the pistons and rings cant seal as well against the cylinders, thus necessitating more fuel for proper running, ie richer condition, which is what a choke does.

Which all leads me back to the first point, that if the engine needs more fuel to run, then it is not warm enough to be run safely without wearing parts more quickly, as the oils viscosity is too high when cold.

But its up to you, if you like to drive your engine when cold, or get up for work at the last possible minute like I do and dont have time to warm up my everyday work hack, then a choke might be beneficial to cold running performance.

Blah blah blah, geez i crap on.

[Benjamin]

No, you make a very valid point, and make it well. It makes me feel as though I am hurting my engine unknowingly, which I am not meaning to. I give her between 3-5 minutes of warm up every morning, and cruise until the engine feels a little freer. Even up to that stage things are fluffy.

My engine is just a bloody cold one, even in the scorching summer I have never experienced anything beyond 1/3 on the temp gauge, even in Melbourne peak hour crawl.

I only travel 5 or so Km into town, so methinks now that the weather is warmer, bicycle is beckoning.

This is an interesting topic but probably not R&D so much any more

Cheers

[goldgemy]

hey ive done the mod on my gemy it wasnt really that hard but got me thinking though like you said get r longer stud for the braket and shape the braket to suit but when i did it i bent the acclerator out slightly because the cable keeps on jaming on which isnt a good thing when your in 1st gear and the accelerator wide open and having to turn the car off and pushing it home trust me i know

Brent (goldgemy)

[MrSHADOW]

Have you ever measured the water temp manually ? or tried fitting a different sender unit ? the one you have might be faulty and sending false readings causing you to think your engine is never getting hot.

Just a thought.