Lotus Elan and Lotus Elan Plus 2 Forums

Hi, I'm new to this forum and to Lotus Elans (my dream car since the 60's). I have just got a 1966 S3 with a refurbished engine (from a +2 I'm told) and a BRM head with twin web's (but I don't know any details about them). It has electronic ignition (Aldon I think). I've yet to have a good look at things (it was a 60th birthday present from my lovely wife of 40yrs marriage). I have a problem with its running. It runs great at high revs (122bhp at 6000rpm on test two weeks ago before I got it) but at low revs it dies if you try to accelerate hard (in any gear). It does recover but you can't accelerate well from a standing start, so pulling out at a junction is difficult. Any thoughts or experiences or advice would be very gratefully received. I'm tempted to take it to a specialist but don't know of one in Sussex/Kent.

Cheers,

Bob

Welcome Bob,
Before getting too involved with tuning and by the way you describe the problem I would first check that the accelerator pumps are working and/or the pump jets are not blocked.

Hello Bob, Welcome to the forum and to ownership of one of the best cars in the world.

FYI Miles Wilkins is in your neck of the woods..... http://fibreglassservices.com/index.html He wrote the book on the Lotus twincam (literally )

There are some clever chaps on this forum but FWIW my approach would be to go back to basics and check things in a methodical fashion. I always start with sparks and then go on to fuel.

I had heaps of trouble all top end nothing low as mentioned junctions oh and speed bumps one would have to rev the nuts off it too go anywhere, the guy who i was using said it was due to wizzy cams,3 attempts later and 3 sizeable bills I got very peed off and asked elsewhere for advice
I found a great garage we had good discussion and eventually I packed my car off.
She was dropping too much oil for a start so I booked her in for a reseal and some other bits and bobs and a good check over at the same time.
Wizzy cams my arse. She now runs so sweet I tell you, I now know why everybody loves the TWINK 2 years of struggling now starts on the button torque low down honestly awesome and still 120 MPH (on the old speedo)
It was a journey though; you need to find somebody that is willing to give you a bit of time even at a price, a rarity in these days, welcome to 2011.
The main point was the timing was out, the two lines on the chain cogs on the end of the cams so the exhaust was 1 notch behind that was the cause of all top end.
The garage I travelled too was realy good realy good I mean realy good.
I am now v Happy, its a shame they are a long way away
I don?t like mentioning garages and personal on the forum but if you e mail me I would be happy to recommend where I sent my car too on a personal basis . it was worth the travel.

types26/36 wrote:Welcome Bob,
Before getting too involved with tuning and by the way you describe the problem I would first check that the accelerator pumps are working and/or the pump jets are not blocked.

I don't know much about Weber carbs but I'll locate the accelerator pump to see if I can clean the jet(s) without altering the other settings. I know that they do work (to some extent at least) since: a) the acceloration is good at high revs and, b) I use a couple of pumps prior to a cold engine start (and too many pumps or on a hot engine and it floods all too easily). Thanks for your help. Bob

nebogipfel wrote:Hello Bob, Welcome to the forum and to ownership of one of the best cars in the world.

FYI Miles Wilkins is in your neck of the woods..... http://fibreglassservices.com/index.html He wrote the book on the Lotus twincam (literally )

There are some clever chaps on this forum but FWIW my approach would be to go back to basics and check things in a methodical fashion. I always start with sparks and then go on to fuel.

Thanks for the welcome and the info. I couldn't agree more about starting with the electrics: in years gone passed I have blamed the fuel on many occasions (and many cars) and it has never been the fuel: a lesson learned well! I will deffinitely try to contact Miles Wilkins.

Thanks again, Bob

Crusty wrote:I had heaps of trouble all top end nothing low as mentioned junctions oh and speed bumps one would have to rev the nuts off it too go anywhere, the guy who i was using said it was due to wizzy cams,3 attempts later and 3 sizeable bills I got very peed off and asked elsewhere for advice
I found a great garage we had good discussion and eventually I packed my car off.
She was dropping too much oil for a start so I booked her in for a reseal and some other bits and bobs and a good check over at the same time.
Wizzy cams my arse. She now runs so sweet I tell you, I now know why everybody loves the TWINK 2 years of struggling now starts on the button torque low down honestly awesome and still 120 MPH (on the old speedo)
It was a journey though; you need to find somebody that is willing to give you a bit of time even at a price, a rarity in these days, welcome to 2011.
The main point was the timing was out, the two lines on the chain cogs on the end of the cams so the exhaust was 1 notch behind that was the cause of all top end.
The garage I travelled too was realy good realy good I mean realy good.
I am now v Happy, its a shame they are a long way away
I don?t like mentioning garages and personal on the forum but if you e mail me I would be happy to recommend where I sent my car too on a personal basis . it was worth the travel.

Thanks for responding. Where abouts is the garage. I live on the south coast near Hastings (due south of London).

Cheers, Bob

bobm3142 wrote:I don't know much about Weber carbs but I'll locate the accelerator pump to see if I can clean the jet(s) without altering the other settings. I know that they do work (to some extent at least) since: a) the acceloration is good at high revs and, b) I use a couple of pumps prior to a cold engine start (and too many pumps or on a hot engine and it floods all too easily). Thanks for your help. Bob

The pump jets are within the carb body and it is fairly significant dismantling to get to them. From what you say about starting then it sounds like at least some of the 4 are working as when mine have been stuck the car has been very difficult to start.

Roughly what is the rev range that this "feature" happens over ? I recall several road testers commented on a flat spot just after tickover and I wonder if this could be the problem you're experiencing. My first thoughts would be to work through the electrics starting with the ignition timing at tick over and a couple of spots in the rev range (the settings are in the manuals for every 1000rpm). If that looks strange, it might be worth checking distributor advance weight are free to move & not stuck.

If you don't have a manual yet (and you really, really, really do need a proper Lotus one) then I dare say a PM to most forum members would get you the relevant page posted

Brian

UAB807F wrote:

bobm3142 wrote:I don't know much about Weber carbs but I'll locate the accelerator pump to see if I can clean the jet(s) without altering the other settings. I know that they do work (to some extent at least) since: a) the acceloration is good at high revs and, b) I use a couple of pumps prior to a cold engine start (and too many pumps or on a hot engine and it floods all too easily). Thanks for your help. Bob

The pump jets are within the carb body and it is fairly significant dismantling to get to them. From what you say about starting then it sounds like at least some of the 4 are working as when mine have been stuck the car has been very difficult to start.

Roughly what is the rev range that this "feature" happens over ? I recall several road testers commented on a flat spot just after tickover and I wonder if this could be the problem you're experiencing. My first thoughts would be to work through the electrics starting with the ignition timing at tick over and a couple of spots in the rev range (the settings are in the manuals for every 1000rpm). If that looks strange, it might be worth checking distributor advance weight are free to move & not stuck.

If you don't have a manual yet (and you really, really, really do need a proper Lotus one) then I dare say a PM to most forum members would get you the relevant page posted

Brian

Thanks for the reply, Brian. It runs well at any revs including tick-over, but from tickover up to about 2000 rpm it dies if I don't accelerate gently. It might be that the acceleration at higher revs will improve too if I sort this problem (wow! is all I can say to that). I am going to start from the state of the plugs and work my way through the ignition and then ignition timiing. It has electronic ignition so I have yet to work out how the auto advance and retard. works. Modern electronic ignition sorts the whole thing out but mine might still rely on the distributor for the auto advance.

The response has been anazing. Thanks guys I'll let you know how I get on.

Cheers,

Bob

UAB807F wrote:IThe pump jets are within the carb body and it is fairly significant dismantling to get to them.
Brian

Actually the pump jets are very easy to check, the pump circuit is a little more complex.
1. brass screw covering pump jets (4 off)....remove
2. showing jet in carb. ....pull out.
3. showing carb with jet removed.
4. jet....has small hole in end....make sure is not blocked.
While the jet is out, work the accerator linkage and petrol should come up jet hole. If it does not then the job them becomes a little more difficult as you have to establish why the petrol is not being pumped.
NOTE. when refitting the jets it has a "flat" on the body so it can only go in one position.

Bob,

As you can see, from the above responses, you've come to the right place. No shortage of help when required.

Your starting point reminded me of this one, from Roger :

elan-f14/weber-problem-t21985.html

It would be useful (for future tuning, whoever does it) if you can identify the current details & "state of tune". BRM head? Re-jetted carbs? e.g. As you can see from the above thread the choke sizes were called into question.

However... it's often writ that "90% of Weber carb probs are ignition faults" so as John has said "go back to basics and check things in a methodical fashion".

Good luck - Richard

P.S. My better 2/3rds only got me a Ferrari (experience) for me 60th

types26/36 wrote:

UAB807F wrote:IThe pump jets are within the carb body and it is fairly significant dismantling to get to them.
Brian

Actually the pump jets are very easy to check, the pump circuit is a little more complex.
1. brass screw covering pump jets (4 off)....remove
2. showing jet in carb. ....pull out.
3. showing carb with jet removed.
4. jet....has small hole in end....make sure is not blocked.
While the jet is out, work the accerator linkage and petrol should come up jet hole. If it does not then the job them becomes a little more difficult as you have to establish why the petrol is not being pumped.
NOTE. when refitting the jets it has a "flat" on the body so it can only go in one position.

Mny thank for the info and the photo's. Really, really helpful.

Bob

ardee_selby wrote:Bob,

As you can see, from the above responses, you've come to the right place. No shortage of help when required.

Your starting point reminded me of this one, from Roger :

elan-f14/weber-problem-t21985.html

It would be useful (for future tuning, whoever does it) if you can identify the current details & "state of tune". BRM head? Re-jetted carbs? e.g. As you can see from the above thread the choke sizes were called into question.

However... it's often writ that "90% of Weber carb probs are ignition faults" so as John has said "go back to basics and check things in a methodical fashion".

Good luck - Richard

P.S. My better 2/3rds only got me a Ferrari (experience) for me 60th

Thanks. Yes this is deffinitely the right place for info and help: I'm blown away. I've been caught napping. I thought, to myself, that it will take a few days (or more) to get any response so I'll pose my problem and still have time to do a few simple checks but I've not even had time to look at the colour and gap of the spark plugs (not even managed to count them yet!!). Actually the previous owner said that it was a bit lumpy, probably due to an issue with cams and best keep the revs up. I know this problem is nothing to do with cams!

Cheers,

Bob

types26/36 wrote:Actually the pump jets are very easy to check, the pump circuit is a little more complex.

Yep, you're right Brian. I claim a "senior moment" as Terry Wogan used to say

I was off beam and thinking about when I've had problems with them not working after a lay-up when it's been down to the moving bits inside the body being gummed up with whatever it is that modern petrol leaves behind when it evaporates. The only way I've ever fixed that satisfactorily has resulted in a complete strip-down.

Brian

ps iffy between idle & 2000rpm ? isn't that the idle/slow running circuits ?

Hi Bob

I live near you so may be able to help - have sent you a pm (private message).

Best regards
Ian