What on earth is carburettor jetting and how do I do it? :(

[RobinOliver]

Unfortunately I'm of the age that multi point fuel injection, wasted spark coilpacks and MAF sensors make a lot of sense.

So when I got my hands on an old Lada Riva, and it wouldn't start, I looked at the carburettor and thought "what? no."

This strange contraption in this case, after some googling, appears to be a turd of a device.

After more googling, something called a "Weber 32/36 DGAV" fits, which from my understanding uses hot water to operate a choke, which increases the fuel to air ratio on a cold engine to aid warming up and idling. It may or may not be the right one, and may or may not have a fuel return line, but I know it fits my inlet manifold.

Now, the issue I think I'm going to have is that the carburettor is made for a 2L ford pinto engine, and that means that it's going to be chucking a fair bit more fuel in than my 1.5 needs

So after yet more googling, I understand that I need to re-jet my carburettor.

I haven't a clue what one of those is, can anyone offer advice?

[gavs1]

Undo the 6 bolts around the top of the carb, in the bottom of the fuel bowl ul find 2brass screws, they be your jets, you will probly find them bein ok for starting, with out seeing the numbers on the jets can't be sure if you got a 1600 carb or a 2 litre carb, I'd dump the cac water choke fing, put a single manual choke flap,

[markgenesis]

It will be a total guessing game unless you can get the car on a rolling road with an operator who knows about carbs (rare these days) even then you'd need a mountain of jets and emulsion tubes etc to hand to make adjustments and all that rolling road time wont be cheap.

Best option i think is to get a Weber for a 1600 Crossflow, that wont be far off what you need for the 1500, either use that or use the jets and emulsion tubes out of it (probably best to use the complete carb TBH).

The Weber is not a "Turd of a Device", was fitted to thousands of cars back in the day, will work very well if in good condition and set up properly.

[usedabused]

I think he means the carb fitted at the moment is a turd of a device,Probably a "pooburg"??

[Dez]

the advice you have been given here is good. to get it 'right' would involve rolling road time and lots of jets, which would cost far too much given the cars value.
so, to play it safe and stop you damaging bits, erring on the side of slightly too rich is a good move. meaning a 1600 carb would be ideal. as you have rightly pointed out, a 2L one is likely jetted too big.

oh and usedabused, lada owners wish they had a carb as good as a pierburg!

[mgbgt stop]

Sept 9, 2014 0:26:45 GMT RobinOliver said:

Unfortunately I'm of the age that multi point fuel injection, wasted spark coilpacks and MAF sensors make a lot of sense.

funny that!! I'm at an age were maf sensors fuel injection and ecu s are a black art and i can re jet carbs adjust the dwell angel on the points and put oil in the top of an su lol lol

[docjohn]

Are you certain that the carb needs replacing? There are dozens of reasons for non-starting, and it seems a bit drastic to chuck the carb away and go down the route of making a completely different one work. Unless you've got a gas analyser at the very least, or a wide band lambda sensor, you'll not get far without a rolling road session.

[RobinOliver]

I'm prepared to have it done on a rolling road, having discussed with the seller about the old carb he's said although it probably works, its not worth saving.
theres corrosion galore, and having been sat for five years it's simply not going to be economically viable. by the time I've paid for a set of new solenoids, a new lambda sensor, made the EGR system work and sourced a new hot water choke unit, which is seized solid, it's cheaper to get something bigger and better and spend an hour or two on a rolling road getting it running reasonably. these carbs are a running joke amongst the Lada community, known as the "horror carb"

A guide to carburettor jetting or something along those lines is what I'm after really, I'm not after advice on keeping original bits.
if none of it works, I'll just flog what I've got and go balls deep with a conversion to MX5 running gear, clutch system, clocks and management by buying a whole car and just swapping the lot over.

the car owes me £50, and the carb £80, so it's nothing I can't make back.

[docjohn]

You can rejet fixed jet carbs like Webers yourself. If you haven't got a large stock of jets you'll need some model engineering drills in a variety of small sizes. Richen by drilling the jets bigger, go leaner by soldering them up and redrilling. Look for a good diagram of your particular carb and identify the idle circuit, the main jets, and the air correction and emulsion tubes. Make sure all the ignition side is right first then systematically work through it. I start with idle first, then move on to getting a smooth transition to the the main running conditions with no stumble or hesitation. Do the primary circuit first, you can run slightly lean, then the secondary which really needs to be spot on stoichiometric for good power.

[gavs1]

Seriously don't drill jets, burtons will sell you jets from £1.50, worth given them a bell explain what you have and what you want and there knowledge may help you, and suggest the rite jets, for probly not even a tenner, I've built my carb to work with a 1.6 zetec, then to a 1.7 race pinto, then a rs2k engine, I've just finished rebuilding and re jetting it to a 2.3 galaxy engine,
Your next issue which could be a headache will be ignition timing

[melle]

If you want no hassle call Fast Road Cars, get a brand new cheap Weber 32/36 DGV (manual choke) and have them jet it correctly for your engine at a little extra. They also have the DGAV which is a bit more costly.

[melle]

And buy a Haynes carburettor book off eBay!

[goldnrust]

As another person who knows more about EFI than carbs really, a friend lent me this book when I first dipped my toe in the water with jetting car carbs (I know what I'm doing with bikes but that's needle jets rather than emulsion tubes), I found it useful to understand the concepts of what each jet does and why.

www.ebay.co.uk/itm/Weber-Tuning-Manual-IDF-ICT-IDA-DCOE-NEW-p-n-weber-tuning-book-/290764737111?_trksid=p2054897.l4275