Restauration result of a Lotus Excel SE

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CID
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Restauration result of a Lotus Excel SE

Post by CID »

At last during the lock down I made some work of completing the restoration of my Excel.

I did a lot of work already and replaced/refurisched nearly everything what was NIO.. interior, brakes, engine parts, carbs cam belts... nearly everything.
But I must admit I did not drive the car a lot during the 7 years... because it didn't drive properly at all(and some other projects). It was not Lotus worthy :cry: :cry:

So the the lesson learned I had about my main problems were:
1- Brakes: Due to saggy springs in the front (drop nose) the G-force balancer was confused and added too much force to the front: After replacing with new spring from SJS problem solved :o
2- By testing at idle and choke the spark plugs are fooled quickly: This gives a wrong interpretation of the problems: Be sure the sparks are clean. The car needs to be driven.
3- The ignition: I expelled Lucas, the prince of darkness, out of the car by a 123 ignition system. In some way the High Energy ignition was not right. Is it because the after market parts were not right, I don't know? But still with the 123 spark was stable at all revs + programmable.
4- I had still a serious hesitation around 2000 which did not really go away (more then normal with standard idle jets): After buying an AFR reader with lambda probe and 2 bungs (1 in each downpipe) I could see that idle was perfect.... BUT during acceleration on the road, the amount of fuel from the acc pump was much too little. Although I thought that I set up the amount properly during refurb?? After some experimenting with acc-settings/also ignition, the engine was transformed in the Lotus engine I was expecting to have. Crispy throttle response and serious power YES . Not to mention the noise. To my opinion.. an AFR equipment is just a must to self adjust carburetors and would give you more reel life situation.
5- AND at last the cosmetics: Besides the interior which was already been out completely and refurbished/painted again + new dash re-trim. I also decided to respray the car + wheels (which turned out to be much more expensive) + replacing all rubbers decals etc..... Now the car is where I wanted to have it.

And here is the result on google photo: https://photos.app.goo.gl/EkYagcf3fEMe2guk9

Rgds Curt

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Re: Restauration result of a Lotus Excel SE

Post by bash »

Very nice Kurt, well done, go and enjoy it now.

Bash
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Re: Restauration result of a Lotus Excel SE

Post by Sparrow »

Wow that looks amazing :D
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I haven't seen daylight in 17 years now i have been finally rescued :D

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Re: Restauration result of a Lotus Excel SE

Post by Marcus »

Well done - the photos look amazing. Does anybody know how many of the l.h.d. European Excels are still on the road?

What type of equipment did you use to measure the AFR?

Marcus

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Re: Restauration result of a Lotus Excel SE

Post by Lotus-e-Clan »

Great result CID. 8)

I too use a dashboard AFR meter (in the Clan which also runs twin DHLAs). An AFR meter is a great educational tool.

You have individual air filters rather than the plenum air box which means some setting changes away from std for fueling and ignition are likely required.

Many overlook ignition tuning - which is also made easier using an AFR meter - the weak AFR reading during a 2000 rpm stumble can be covered by enrichment or by advancing ignition (weaker mixtures need more advance).

I can make my Excel stumble around 2000 rpm simply by turning the OE distributor anticlockwise (retard) by just 1 mm. Also my Excel SE goes really well throughout the rev range with a tad more advance over std, but then you definitely need 99 octane fuel to prevent pinking on WOT when in the lower-mid-rev-range when under load. Also worth considering, hot ambient air temperature exacerbates pinking hence you can safely run a bit more advance with a cool air box rather than open underbonnet filters.

If you run the AFR meter in the dash at all times it would be interesting to see what AFR values you are happy with for part throttle cruising and at WOT (wide open throttle) full power. My Clan goes best with a full power/max torque AFR @ 13.0 - 13.2:1 and cruises nicely around 15:1. It idles around 14:1.
A tuned climax /imp engine likes a relatively weak full power AFR around 13:1 but many engines like it richer at around 12:1. I don't have a dash AFR in the Excel so it would be interesting to see your running AFR values for the Excel if you have any to share. :D
Peter K

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Re: Restauration result of a Lotus Excel SE

Post by Alan_M »

Looks very nice.

Interested in what maps you’re running in the 123 as I also have one of these. It was on the car when I bought it, but the vacuum advance map was way off and there was an issue with the thermal control valve so had little power bellow 3000 rpm.
Is yours the Bluetooth version? If so as you can change ignition advance while driving would be interesting to know if that changes the stumble.
Also be interested to see what maps you’re running.
As to the foam filters you have be careful as these increase the risk of engine fires. It’s much easier for fuel to drip onto starter.

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Re: Restauration result of a Lotus Excel SE

Post by CID »

Thanks for the nice words everyone:

@Marcus, As AFR I use Zeitronix from EFI-Parts.co.uk It is very fast. So for idle speed you can distinguish which carburetor has which AFR reading and adjust it.
I think there were only a 49 LHD Excels? Can someone confirm?

@Peter, Thanks for the info :wink: ... Well I did not LOG my AFR data as I did not have an input for the revs. I kept it to the richer side during acceleration. It started from 17 at first and that was quite a problem :shock: But it could be a nice addition to try to incorporate the revs in the log of the AFR. I will try to safe the log next time. Having it on the dash is quite convenient. I used a laptop on passenger seat, not so safe :oops:

@Alen, First I was using mine, starting from measurement of STD distributor, I used later the one from Phil. See in this thread viewtopic.php?f=33&t=9033&hilit=123 But I think it is changed some bit. Will also download it nxt time.
You also find the one I measured from my set-up in the beginning
I have an older version with USB cable + laptop.
About the carb socks. I was indeed a little bit afraid. But as you are working on an engine problem it is easy to remove them. Seems also that they are made of fire retarding material these days. But I will go back to the normal intake soon if all runs fine. I also think that the induction noise will be gone? Or not?

Rgds Curt

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Re: Restauration result of a Lotus Excel SE

Post by CID »

Lotus-e-Clan wrote:
Mon Sep 20, 2021 08:46
.......
If you run the AFR meter in the dash at all times it would be interesting to see what AFR values you are happy with for part throttle cruising and at WOT (wide open throttle) full power. My Clan goes best with a full power/max torque AFR @ 13.0 - 13.2:1 and cruises nicely around 15:1. It idles around 14:1.
A tuned climax /imp engine likes a relatively weak full power AFR around 13:1 but many engines like it richer at around 12:1. I don't have a dash AFR in the Excel so it would be interesting to see your running AFR values for the Excel if you have any to share. :D
@Peter,

To come back on this matter of AFR. It seems on an Excel SE the values at continue revs @ cruising are quite conservative. From 2000rpm constant (cruising) on the AFR is always 14.5/15.
On acceleration is goes down AFR 13-12. It is not so easy to get AFR reading stable @ acceleration. But she goes ... like it should be. So I did not try further.

I also noticed that while you are in too low revs you can go to AFR 10 and loose all power as a carb needs enough air to cope with the squirt out of the acc pump which is always the same.

Regards Curt

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Re: Restauration result of a Lotus Excel SE

Post by richardw »

That’s a lovely car Curt - well done. And a good year to put it on the road as it is the 40th birthday of the Excel.

Going back to the standard airbox should reduce induction noise. Rolling road tests done on the Jensen Healey forum show that mid range torque is better as well.

Cheers, Richard
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