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Help with problem


Mike6

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Going over the bleeding obvious - is your flywheel definitely marked correctly?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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  • Gold FFM

I can't believe this is still going on, because despite the best intentions of all those nice people giving you advice, this forum tennis match looks to be going nowhere. They'd be better off recommending somewhere, or someone, you can take it to.

Margate Exotics.

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Pulled the cam covers today and checked operation of cam followers (they were all renewed a couple of years ago) and they move smoothly up and down against the cam itself. I then checked the gaps a number of times according to the manual and they were all within tolerence ie around .15mm for inlet and at the upper end for exhaust ie .3mm. I could see absolutely nothing wrong nor any evidence of sticking valves. Hopefully that means I can eliminate any possibility of valve bending or other damage?

I then completely rechecked timing bringing piston 1 to tdc and then checking the markings on the cam wheels (including correct orientation ie inlet dot and exhaust dot correctly lined up) and that this corresponded exactly with tdc marking on flywheel which it all did. Could not use strobe as now awaiting cam cover gaskets but have done this endless times and it is 10 degress btdc (it is marked on the flywheel!)

By my reckoning that just leaves blockage in the exhaust system or carb issue to work though. Fairly certain it is not the petrol but will check. 

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I don't think this is anything major. It's very easy to get frustrated and start tearing the engine apart....I've been there with everything from a 2 stroke outboard to an Esprit Turbo. In every case, the problem turned out to be something minor I hadn't even considered...the outboard was an air leak through a seal on a mixture adjusting screw, and the Lotus was a leaking exhaust manifold. Any large scale mechanical disruption is immediately obvious...loud clanking noises or bits hanging through holes in the side of the engine. I think your problem has to be either ignition, carburettion or valve timing. I'd write up a log of exactly what you have done and what the results were.... writing it down helps you to analyse things. Also, just because you have checked something 10 times, doesn't mean it's right!! I have been known to check the same thing time and time again...and make the same error each time, convinced I was right....until light finally dawned. Think through everything, go back to first principles and make sure that everything you do makes sense from that point of view....even to the point of ensuring you have TDC by poking a screwdriver down a plug hole to make sure the piston is at the top....and checking the distributor to ensure it's the firing stroke...that sort of thing.

None of this is magic....has to be amenable to analysis...."just keep thinking, Butch...that's what you're good at.......!" 

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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  • 2 weeks later...

Now back from hols  and decided to try Sparkys idea of blocked exhaust. So pulled it and took it to Kwikfit. They put an air line through it both ways and all seems fine so will now move on to carbs.  

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Exhaust now reconnected plus cam covers and vacuum pipes on dissy. Car started first turn of key (this is the early Stevens carb turbo) and ticked over fine which in itself after about 2 weeks of sitting there must indicate most life signs are healthy. Rechecked for about the tenth time the timing which was spot on - my strobe has the advance dial on it so set to 10 degrees and light static bang centre of the tdc stamp on flywheel. 

Got the wife to sit in the car to check rev counter and with engine nice and hot increased revs slowly. They got to about 3500rpm when engine started to hesitate and revs fell back to around 3000rpm themselves and putting more throttle on made it worse in terms of the hesitation and she backfired (car not wife). Taking of throttle car returned to normal tickover. Reading up in the service note it says operation of carbs and pump diaghram changes about these revs so is it looking like a carb problem all along??.

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Hi Dave

There are only a few markings on the flywheel so not really possible other than to say markings did move - I have previously checked. Its a rebuilt dissy etc so cannot  think what could be going wrong in that region. Cannot check now as carbs off the car and strip down started. 

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Wow, that was quick. Good luck finding something amiss there, though it might be worth putting a blob of tippex at the (29 deg??) most advanced point on the crank pulley to check when it's next together.

ATB

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Had a similar problem a few years ago which had Sparky head scratching for awhile.As car comes off idle jets it requires more fuel which it wasn't getting because of blockages in fuel lines.Enough fuel getting through to tickover and run atlow revs but not enough getting through when under power at higher revs

hindsight: the science that is never wrong

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Well hopefully tomorrow this will be the end of the story????. Spent yesterday stripping and thoroughly cleaning the carbs. A bit of crud here and there but no blockages or blocked channels that I could see. The accelerator diagrahm looked a bit slack (which could affect progression/acceleration. Had the carb kit so replaced all the bits and pieces. Put it all back together today and she started on the turn of the key, balanced the carbs and rechecked timing. 

Then took revs up, all ok up to 3000 rpm and then I thought I saw of bit of a rev drop but could have been me taking pressure of the throttle cable. Then pushed her up to 4000rpm without issue - Eureka. A hell of a lot of popping when i released the throttle but it is the carb turbo with SJs stainless exhaust.

Now have to clear everything out of the way - I am a messy worker and tomorrow will take her out on the road. 

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  • 3 months later...

Thought a few people may like to know how the problems that plagued me over the summer have been resolved by the new owner - car was taken to Belgium around 3 months ago. New owner started by going over everything I had done and could find no fault. There was a bit of play on the turbo shaft so he had it recond but it made no difference. Ultimately he purchased a wideband lamdba kit which showed that as the throttle progressed the mixture weakened to the point at around 3000 rpm car started popping and banging and revs died back.

He tooks carbs apart and although I had rebuilt them the service kit (from a well known Lotus parts supplier) contained components like the accelerator pump, spring and diaghram from the earlier non turbo Esprit which were not man enough. He replaced these and car immediately ran better. The kit also suggested that larger main jets would improve things further and he is purchasing these.

When I think back I feel really miffed that had I been provided with the right parts (kit was made up by seller) then I would probably still have my car but there is no point letting this get you down - and I did see 4 Esprits at the recent NEC Classic car show so I had an appropriate fix.

I now own a very nice Z4 but somehow its just not in the Esprit league.   

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Wow, how disappointing and frustrating.  I do hope it was a one off mix up by the supplier?  Did you contact them to advise so it doesn't happen again? How would we know if we got the wrong parts in the kit?

Thank you for the follow up.  I am probably going to do a carb service/rebuild in the near future so I want to make sure I am getting the right parts.

My ex wife had a BMW Z4, 3.0 6 speed, 2006.  Super smooth and fast, but lacking in character compared to an Esprit and bloody terrible reliability and quality to what I thought would be a BMW.  Alternator failed, cylinder head was rebuilt under warranty, rubber around the windscreen crumbled, and the hood mechanism failed. Oh, and I found the seats a bit too firm for a long journey, so I let her keep in the divorce...... :P

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What a shame Mike!!!

I have rebuilt quite a few Dellorto carbs over the years i always buy the rebuild kits from Eurocarb the official UK Dellorto carb distributer and never had any problems.

 

Was it a specialist Lotus parts supplier that supplied the parts?

 

Cheers Mike

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The accelerator pump diaphragm and springs are the same for turbo and N/A cars though.

The differences are in jetting and the design of the top covers are slightly different with different gaskets to contain the boost pressure and the butterfly spindles have seals.

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Going back to one of my earlier posts...there never was going to be much wrong with it. Most of the stuff that was done comes under the heading of pissing into the wind. Attempts to mend something by trying everything one can think of are doomed to failure; it is DIAGNOSIS that has to come first...you have to find out what's wrong. Fitting a bunch of new parts will never guarantee a fix. I've been there myself....reconditioning the turbo, for example, was never going to help. it is immensely frustrating and tedious, but finally you do get the solution. I'm not even sure that the solution has been found now... although the standard carb. jets are at the limits of what they can cope with, and even the smallest reduction in diameter and hence flow gives problems, as I found myself. Don't believe that accelerator pump diaphragm or springs is going to produce the symptoms; you might get a "flat spot" on acceleration, but not the misfiring as the RPM rises past 3500 or so. As Andy says, the Turbo uses a "pressure" carb that allows the float chamber to be pressurised so that the pressure gradient across the jets is maintained. Anyway, it's someone else's problem now......and good luck to them!

Scientists investigate that which already is; Engineers create that which has never been." - Albert Einstein

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