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Rough running BDR Cossie


markc

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Hi All

My BDR is not well, it starts and runs ok when cold but when it gets warm its running realy rough until it gets to 3k then it clears and runs ok ?? any ideas ?

 

I am planning on doing a service on the carbs to see if that helps.

 

Its a std 1600 with an Emerald 3d ignition.

 

The car has never given me a single issue since I got it, We had an issues at Llandow which was caused by a broken alternator, In trying to fix this issue I let someone adjust the carbs, since then I have had this problem, could this be carb related ? I would of thought that if the carbs were the problem I would get the problem if the engine was cold or hot ??

 

Many thanks

 

MarkC

 

 

 

Edited by - markc on 16 Sep 2012 14:31:21

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golly i hear that! worst job bar none! had them on and off too many times in the last month or two.

 

in the end I surrendered and each time removed the two pairs of bolts holding on the accelerator retaining "bar" thing, one from each carb to allow access to the carb retaining nuts behind - a real pita. I'd rather do any job than that. Trouble is it makes everything else in those nether regions so easy - or indeed possible. I mean whose idea was it to put the dizzy down there? ffs! I currently have old fashioned points in there, though my electric ones will be back in first time I have the energy to go there once again...long story short, the new coil was goosed.

 

oh yeah, don't forget "carb cleaner" (spray cans) - great stuff. cleaned practically the whole car with it! 😬

 

there's a useful site of a guy in South Wales who refurbs carbs... which kit have you chosen and why?

 

oops.. mine are dellortos.. imagine it's the same tho in this regard.

 

 

ISBN 1-901295-64-8

 

 

 

Edited by - anthonym on 16 Sep 2012 19:58:45

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😬Anthony - I found I could just about undo the nuts without removing the throttle thing, trouble was I couldnt get the carbs off without removing it *cool*

 

I am now looking at the car thinking what needs to be done to it now I can get access to all those things that are under the carbs. Will replace the fuel pipes and add the optimax(charger) cable onto the battery to make life easier 😬 Had thought about moving the battery but cant work out where to put it, I like the idea of putting it in the boot *confused* but not sure how easy that would be. What I need to do is use the car 😬 its an "89" car with 20,000 miles *eek*

 

One day we will meet up

 

Regards

 

MarkC

 

 

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hope so, visit any time :-) . had my first outing today, I do love the engine noise, not as quick as the r500 but wonderful .. feels like going back in time and def not slow! had the adrenalin shakes ! 😬 😬

 

 

I have just spent 80 days fettling my bdr so feel free to quiz me - for example maybe lift out the petrol tank and "service" everything that comes into view, such as earth points for lights as well as fuel lines.. the ethanol (?) is apparently causing issues so a solid fuel feed from pump to front is a good idea.

 

Edited by - anthonym on 16 Sep 2012 20:05:21

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Anthony

 

I have that book, will have it near me when I start stripping them down.

 

I bought the Webber service kit from webbers at Sunbury, just round the corner from me.

 

Im based near Hampton Court if your ever this way.

 

Will report back on how it goes and what issues I have 😬.

 

Dad rebuilt his carbs from his elan sprint not long ago, thats why im getting him over to give me a hand *cool*

 

MarkC

 

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from the book ISBN above page 92 low to mid range rpm problems: "If the emulsion is wrong the engine will "stumble" then clear as the revs rise. This "stumble" is caused by acceleration phase leanness and a richer mixture can be provided by changing emulsion tube" .. ok so given it was ok before I wonder if this is suggesting a mixture issue and I see you have an emerald, does that mean you can twiddle the mixture with mapping?

 

The quote doesn't mention temperature.

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Anthony

 

Have just got the book off the shelf to read it again *cool*

 

The emerald is 3d ignition only as I dont have fuel injection *cool*.

It allows me to adjust ignition timing to revs and throttle position.

 

It has been fine until that day, its never been the same since.

 

If all else fails I may take the BDR out this winter and stick in the 1760 x-flow thats under the bench 😬 But like you I do love the sound of the BD and it brings back so many memories of Dad's BD's although his ones reved a bit more than mine and had bags more power 😬

 

MarkC

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Personally I would have checked the carb balance with a synchronometer before dismantling them if they had been "adjusted" by someone just before the problem occurred.

 

I nothing has been changed on the engine ie cans / timing etc then the jets and emulsion tubes will not need changing. If you have the carbs apart clean the jets and tubes by blowing through with compressed air.

 

When refitting the carbs to the manifold don't over tighten them.

 

They will then need re-balancing with a synchronometer and the idle set up.

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Toby - I wish you still had yours too, would be a great engine for our Mk1 project 😬

 

John

Thanks, I had thought about just balancing and trying to get things back to normal, but also felt it was time for a little service, shouldnt think they have been done since they were new. I have a carb balancer and will get the car rolling road set up later when its running a bit better, last time it was on a rolling road was when I fitted the Emerald.

 

Regards

MarkC

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yes ftsoc (for the sake of clarity), I wasn't suggesting change of jets or anything; just that the text indicates symptom caused by mixture issue at low to mid range per op.

 

and yes, I found that appropriate doing up of the 8 carb nuts directly affected performance; loose but not too loose, and def not tight.

 

still wondering how you got those two inner lower nuts off without removing the throttle bits.

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Mark,

 

Did this person "adjust" the carbs or did they change things like jets, emulsion tubes, etc?

 

If they only adjusted, then it's possible that they have simply left the slow run screws too far out leading to excessive richness at lower revs and throttle openings. This would tie in quite neatly with it being worse hot than cold.

 

Equally, if they actually changed things, they may have put too large slow run jets in - or they may even have drilled out the originals (in which case you won't be able to trust the sizes stamped on them).

 

Emulsion tubes are also a possibility, but you really need an expert to have a look becasue there are so many other things that could have been done (float heights, pump jets, etc).

 

My advice is to never let anyone mess with DCOE's unless they have a proven track record. They're not difficult, but as with all things, you have to understand what you are doing and why. In particular, never trust anyone who knows everything; you can usually spot a genuine expert by a willingness to occasionally say "I don't know".

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Hi Roger

 

Thanks for that 😬

 

Nothing was replaced or drilled out, the only think the "expert" did was fiddle with it, turn this turn that and adjusted the float heights.

 

I will attempt to service them and then give it another go, then its off to a real expert if I fail.

 

Good to know that "If they only adjusted, then it's possible that they have simply left the slow run screws too far out leading to excessive richness at lower revs and throttle openings. This would tie in quite neatly with it being worse hot than cold."

That makes me feel alot happier as I was thinking of all the worse possible things 😬

 

Many thanks

MarkC

 

 

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The only time my BDR ran well on carbs was when this bloke called Roger King overhauled them and the head. I've never heard such a quiet BD or had one so smooth. No rattles or anything from the top end!

Shame he gave up, all that dealing with k series owners I tink 😬

Hi Roger *wavey*

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Awwwww..........................I'm blushing now.

 

Actually the first engine I ever built was a BDA, back in the 1970's. I'd been working for Brian Hart for about a year when I was just handed a box of bits and told to get on with it - a 1600cc Formula Pacific engine.

 

It would have been nice if they could have eased me in with something a little more mundane, but we really only did the 420R Formula 2 engine and the works BDG's for Ford. I guess the Formula Pacific was the nearest we had to ordinary, but in those days a 16valve engine was seriously exotic.

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Still one of the best engines ever!

By God, I give mine some stick on track and it never ceases to amaze me 😬

Having someone who really can set your carbs is so important.

If they are original Caterham supplied ones watch it, Roger told me that they bought a job lot that were destined, I think, for Lancia because they got them cheap.

They never quite worked...

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In fairness to Caterham, it wasn't them who bought the unusual carbs; they were supplied by Cosworth and they were very different to normal ones, with great long aux vents, huge chokes, etc. I never did get the definitive version, but someone at Cosworth told me on the quiet that they'd picked up a job lot cheap - although I must stress that this was heresay and I have no proof.
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