Weber 40DCOE Issues

[Galwaylotus]

I finally have the time to try and sort the idling and part throttle running problems on my S3 SE. I first must say that I can only work outside. I don't have a garage to use.
I was finding it difficult to start the engine and when I finally got it running it wouldn't idle. Indeed, after running for a very short while it often would die. When I did get going I needed to keep revving the engine and part throttle running was an impossibility.

I contacted Keith Franck and bought his Hypojets and E-tubes but haven't yet installed them because I wanted to sort the gross issues first. Keith is an extremely helpful person and pointed me in the right direction for a few checks. As I recently retired I can now spend the time to get things done right.

What I started with was to check static ignition timing. I ended up making a 4? adjustment closer to TDC and this seemed to make starting a bit easier. Next was to get the car as level as I could and check the fuel level per Keith's methodology. Both carbs' fuel levels seemed to be low so I removed the top covers and checked by the Lotus and Weber manual method (8.5mm and 15mm respectively). This confirmed that the levels were too high so I adjusted them accordingly.

Next I looked at the setup on the car and almost immediately realised that I had adjusted the balance screw at some time previously instead of the idle speed screw! I also checked the idle mixture screws (which I never adjusted) and found each of the four was turned out 2.5 turns as against the manual's suggested initial setting of 3/4 of a turn. Finally I checked the gaps on the Thackeray washers and discovered the front top one was broken. Worse still, the front lower washer and nut was missing altogether!!

At this point I decided I should probably get a couple of overhaul kits and start from scratch.

Why am I writing this? I hope to help others who are having problems by advising that they check all the basics first before doing anything else. Watch this space for updates.

[gjz30075]

I'll be watching

[Galwaylotus]

Ok. Here's an update. I have overhauled both carbs - and learned a lot in the process! In between the physical work I've been reading and studying anything I could find on DCOEs including both of John Passini's books which I've owned for MANY years but never sat down to read before. This retirement craic has benefits!! While thye Webers were off I decided to pull the distributor and install electronic ignition - Powerspark in my case. I also took Keith Franck's advice and had all the endplay taken out of the distributor, had a new o-ring installed and pulled the weights and springs for a good look and clean/lube. It's all back together and I had access to a distributor tester the other day so I mapped the advance and found it very close to the Lotus spec for that model (40953 A).
I can only work outdoors on my Elan so it looks as though I may have to wait another few days before I get it back together and set up. The current weather outlook is for rain through the early part of next week! I may try to relocate the coil and upgrade it for a Lucas Sports coil that I already have. The relocation depends on someone who has done getting back with photos so I can understand how it was relocated.

[Pistacchio sprint 72]

Hello i would be thankful if you could post a curve graph of your ignition curve?
Also for idle set up, it is more convenient if engine is warm.
Be careful also if many times flies between two carb set up that the fuel loose some octane ratings... Or if the car sits outside and your tank is not full that some condensation happen in the tank.

[Galwaylotus]

The machine that was available was very old and not in great shape so it took a while to get it set up and working. I was conscious of not monopolising all the time of the people helping me as they had other duties and were doing me a favour so we took a few data points and I was satisfied that it was close enough for me to get the engine started (when the weather clears!). The data points are as follows: (all data based on distributor advance and rpm)
100 rpm 0 deg
1000 rpm 9 deg
1500 rpm 10 deg
2000 rpm 10.5 deg
3500 rpm 12 deg

If I had the time on my own and a smooth running tester I would have preferred to capture points at least every 100 rpm up to maximum. This wasn't feasible and my main reason for testing was to confirm that the distributor I have was reasonably close to the Lotus spec. I'm satisfied that I've done that so it's safe to install and try and start the engine.

[Galwaylotus]

I've made no further progress as the weather here has turned miserable and I'm battling a bad headcold. No joy.

[Galwaylotus]

This is the main reason I'm not working on my Elan. Hailstones, cold wind, rain - typical west of Ireland weather this time of year!!