Just to check, this IS the 'Carb from Hell' problem right..?

[seagull2200]

Just become a member - great to see others with a 'wierd' fascination with what should be understood to be simply just another 'Old Banger' - but i like them because, as an ex-biker and student Pilot, i love being able to fix things manually - 300 series let you do this...

On to the problem. i'm now on my second 340 1.7GL. This is a nice example, Milometer stopped at 16'000mls (so expect about 60-80'000!). Bought cheap, with a nice certificate to say previous owner spent £140 on a carb rebuild - lovely, or so i thought.

Went for a drive....... ... ... .

Entered the cruise (pilot talk) steady at 55mph.... went fine for about 4mins,..and then,. it began with just a litttttle 'holding-off' from the engine, almost as though a slight misfire was taking place on ONE cylinder, but then... IT GOT WORSE!!!! The same but more,.. actually now, the chassis is jerking fore and aft, not quite 'neck-breakingly' but you could feel it - so i'm thinking it's an intermittent misfire. If i accelerated to 60-70 - problem gone!

So, it doesn't like being held 'steady' at about 55mph ish.

Ok, so i decide to pull off the A road, and up to a set of traffic lights. As i pull the clutch in to approach the traffic lights to stop - all hell breaks loose!! ".......I'VE BEEN HIT!!" I'm now in my Spitfire, just on finals to the lights - and the bird is shuddering, shaking from side to side, engine induced lateral vibration, the tacho is jumping 200rpm either side of the usual 900 rpm - What the HECK..??!,
I come to standstill at the lights and battle to keep the engine alive, simutaneously banging out a 'Mayday' call and in desperation gunning the throttle, making the family saloon at my side - more to the point, the family 'IN' the saloon at my side, think i'm trying to make some kind of impression - embarrasing and very unprofessionall!

Anyhow, i make it back to the field ok, gear down and parked outside, i stand, new HT leads, Plugs, rotor arm, dizzy cap and air filter in hand - and a BIG SMUG GRIN on my face.....

App 1hr later, i'm in the cruise again and... no .. NO!! It's still there!!, The engine just stopping short of shouting "Bu*^^r-Off..!!" to my feeble attempts to keep a smooth cruise at 55-60ish.
So i decide to leave the A Road........

........looking, LOOKING,.. radar ON for any chance takers... it's gonna be ok, i'm gonna make it.. and then .. 'OH to HECK.., WHAT THE,.....' I've been hit AGAIN - ON THE SAME final approach to the lights!! She's going, SHE'S GOING..... I try in vain to keep her .... again doing a Nigel Mansell whilst stationary next to a Kenneth Clarke - feeling very stupid!.

Onto the tuning specialist - 2hrs later he emerges from the pit... of hell,.. to inform me that i have one of the cleanest 340 carbs he's ever seen - "cheers mate, but how about it's running..?" He's just returned from a test drive (He looks visably pale..) and tells me that he doesn't know the answer. He bolts the hot/cool air seperator flap in the air intake to filter pan manifold, so that it will not take in any cool air - thinks it could be carb ice. This measure helps a little, but not enough to be in anyway pleased.

So i fly off into the sunset.....

......avoiding a cetain sectionof that damn 'A' road....

[seagull2200]

.......On the point of getting a new carb from the breakers - if that would at all be required, didn't renault use the solex (or better variation of..) to fit to the Renault 1.7 engines in Renault's own cars?
What Renault vehicles used the 1.7 engine, AND i'm having difficulty identifying if indeed my 1989 1.7 IS a 'B172', and if it is infact the Solex Carb it uses??

Many Thanks.

[KeithB]

Hi Seagull, wellcome to the wonderful and wacky world of the Solex 28-34 CISAC carburettor. I've had my 340 1.7 for approx 180,000 miles so have had a few "problems" with this piece of machinery over the years. Your tale had me in stitches and recalling the last episode of my own last year when I had to drive the car through a one street town on the way to the garage while experiencing the same symptoms, the only way was to maintain revs above the 2000 using a combination of choke and accelerator hoping that I wouldn't be forced to stop, the car was fine while accelerating but wouldn't cruise or decelerate. The stares from the people on the street were quite something, they seemed to think I was getting ready for the start of a drag race.

What was the answer? Like yourself the mechanic reported a clean bill of health for the carb, distributor cap, etc., he stripped down everything and put it back for me, seemed to help for a while,but eventually I cured it myself when I discovered that I didn't have a heat transfer flange under the carb as described in the Haynes manual. A trip to the Volvo dealer and no more crazy antics over the past year! Where was the original? Who knows?, I remember handing over the car to a Volvo dealership in Canterbury with the same problem in '94, they diagnosed air leak at the inlet manifold, did they forget to replace the flange? So the first place to start is checking for an air leak. If you cure the problem let us know how!

Also read your thread on being unable to turn right, interesting problem, haven't the faintest what to do about it though.

Good luck

[foggyjames]

That certainly sounds like fuelling....so I'd check for air leaks (especially around the carb base), this heat transfer jobbie Keith mentions. Are there any other symptoms? For example excessive fuel consumption or noises / smells?

cheers

James