SNAIL

mikehine · Snailer Joined: 17 Jun 2010 Posts: 9

I had a flat spot/hesitation at low to mid revs. I have just had a 123 ignition fitted and it seems much worse. Anyone have any ideas?
I also have backfires sometimes in the carb (frontfires?) when I start up , in case that's relevant.
Any suggestions very welcome.
Thanks
Mike Hine

dyanut · Posted: Tue Apr 24, 2012 11:27 pm Post subject: Re: FLAT SPOT

For the flat spot, if it's got the later type of 26/35 carburettor with 18 & 26mm diameter venturis, change the primary petrol jet from a 102.5 to a 107.

To cure the backfiring, adjust the valve clearances to 0.25mm for the exhaust valves & 0.2mm for the inlets, after re-torquing the cylinder head nuts...

Ken

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mikehine · Snailer Joined: 17 Jun 2010 Posts: 9

Thanks a lot, Ken. Couple of supplemetaries.
It's a D reg Special, 85 or 86. Would that tell me what carb I've got?
Do ECAS do the jets?
I can do a lot of basic things but I'm scared of carbs. Is it straightforward to do?
Thanks a lot.
Mike

dyanut · Posted: Fri Apr 27, 2012 12:40 am Post subject: Re: FLAT SPOT

Mike,
if it's the original carb on that car, it will be an 18-26, but check the numbers cast into the offside face of the float bowl. ( That's the side nearest to the alternator. )

Thinking about it, if the carb base insulator has cracked ( a common problem) or the so-called 'choke pull-off device' has failed, the resultant air leaks would contribute to backfiring when you're trying to start the engine.
Check by spraying WD40 onto the suspect areas with the engine running, if the engine note changes noticeably, those items may need attention as well.

Whereabouts in the UK are you? It might be best to entrust the checks and any remedial work to a specialist if you're not confident or experienced with working on carbs.

http://www.ecas2cvparts.co.uk/info_pages.php?pages_id=23?WSid=b70f1a5c07ec9bb69d9091d71049fb5d

Ken.

mikehine · Snailer Joined: 17 Jun 2010 Posts: 9

Thanks again, Ken. I'm in west London so I've got access to a couple of good specialists. I'd heard about the insulator as well so I'll try your tests over the weekend, order the bits and then maybe get brave with the carb when it stops raining.
Have a good weekend.
Mike

mikehine · Snailer Joined: 17 Jun 2010 Posts: 9

Hi Ken (and anyone else who can help).
I've replaced the jet in the carb but no change I'm afraid.
Coil?
Mike

Bart · Posted: Mon May 21, 2012 6:08 pm Post subject:

Sorry I ask the obvious way; did you check the tappets and the insolation gasket underneath the carb? & possible other sources of air leackage between carb and engine?
It obviously can't hurt to check you ignition, but I wouldn't just say it's the coil.
Generally (and experianced that) coils are good for bad starting.

S O S · Posted: Tue May 22, 2012 1:10 pm Post subject: Re: FLAT SPOT