1.7 Warm Start Issues

Post by **pettaw** » 02 May 2006 08:57 pm

The jetting on these downdraughts is different to your Solex's Foggy. The idle jet is in a different place, nowhere near the mains, and the air jets and main jets aren't joined together.

Chris's running problems are caused by perished bits of rubber getting caught in all the nooks and crannies and gradually working themselves through. I'm not sure that they've necessarily come from the knackered hoses and pump, the mesh filter should take care of that but its possible, but I suspect they've always been floating around in there since you got the car.

Chris you need to do a complete stripdown and clean every component carefully. The reason you're getting crappy fuel economy is just because the car isn't running right and you're wasting fuel blowing it out the back end trying to get the car to run properly.

Post by **Chris_C** » 03 May 2006 12:08 am

Yeah, I'm gonna try taking it off either tomorrow or thurs, just out of intrest, one of the long jets has a very solid block about 10mm from the bottom, the other long one you can pass a bit of fuse wire all the way through and out the top. Should this be there?

Post by **foggyjames** » 03 May 2006 12:15 am

Furry snuff Andy

I was working on the basis that they sound like mine are layed out. On second thoughts, there's only one idle jet on a twin downdraft carb, so it's not looking too good for my advice!

The jetting of the two chokes may well be different, so I'd not worry too much about that.

cheers

James

Post by **pettaw** » 03 May 2006 07:45 pm

Haha was I a bit short Foggy?:D Didn't mean to be.

Erm, yeah good idea Chris. I wouldn't poke anything too stiff through those jets cos they're very soft brass and you might enlarge something you shouldn't

Post by **foggyjames** » 03 May 2006 07:51 pm

Not at all Andy...I was just acknowledging my stupidity

cheers

James

Post by **pettaw** » 07 May 2006 09:37 pm

Well, we had a good meet this afternoon, and a certain blue Volvo 340 1.7 was spotted getting very slightly sideways round a small test track at Haynes museum, more to follow from other people on that one.

Anyway, having now stripped Chris's carb apart again, I have to eat my hat and say that Foggy indeed was correct in his description of the jet arrangment, because unlike the OE Solex, the replacement Weber carb has the jets in exactly the same arrangement as Foggy's sidedraughts.

The air jet sits on top, directly attached to the emulsion tube which is directly attached to the main jet. There also are two idle jets on this carb.

We discovered that Chris's carb was running WAY rich. We corrected the idle mixture easily, just a matter of turning the screw

but as soon as you revved the car up to 2000 RPMs even in neutral the carb went just way rich. So I firstly swapped the idle jets over so that the smaller of the two jets went on the primary. It made a big difference to the idle mixture because I had to back the screw quite a way out to make it idle properly again, but although it made some difference it made very little difference once you opened the throttle even slightly. In the end I swapped over the emulsion tubes and main jets but kept the air jets the same. This seemed to have the desired effect, still very slightly rich on progression but much more manageable than before.

Chris will tell us how it drove back

Post by **foggyjames** » 08 May 2006 12:18 am

Excellent work there chaps!

Much more luck than good judgement on my part...

cheers

James

Post by **Chris_C** » 08 May 2006 01:01 pm

Seems to be great, I took it to Kates last night, 100 miles on £20 again, but that was with 30 odd before tuning, and left idling for a couple of hours, as well as me giving it a bit of stick on the track.

Stuck £20 in this morning, it's done 70miles, and have what looks to be half a gauge of fuel left

I'll have to wait to see what I actually get out of it.

Website · Post by **antiekeradio** » 08 May 2006 01:12 pm

a 1.7 in decent shape should be able to do 14 km to the litre....

Post by **Chris_C** » 09 May 2006 01:05 am

Currently 80miles, and half a tank left...

Using Wouter's 14km to the litre, I make that 185miles to £20, at 93.9p

I'll keep counting!

Post by **SteveP** » 09 May 2006 09:32 am

185 miles to 20 quid.... nah

Post by **Chris_C** » 09 May 2006 09:59 am

I managed 250 on £20 in Kar quite often, more often 210-220, that was when fuel was cheaper though

Still I'm hoping. She feels so much better to drive

I'm dead chuffed... looks like Fake is finally sorted engine wise (touches lots of wood... just in case)