Lotus Elan and Lotus Elan Plus 2 Forums

Dear All,

My original post being here : viewtopic.php?f=51&t=46215
I'm far behind engine check but already looking at good adress while awaiting for pieces and time

Looking after some specialist for rebuilding a Twin cam for my Elan +2 from 68.
I'm located near Mons in Belgium.
I haven't disassemble it yet but it has not turned in the late 30 years and had already 90 000 miles on the clock (without specific history)
I can do it partially, but would need someone to take care of machining valve port, maybe boring cylinder if needed, balancing all around etc ..

So if you ever know someone in Belgium, Good of course

Please let me know !


Thanks

Yves

NB : Joined a video of last owner making it "turn" after this 30 years pause (do not know exactly what he have done prior to that like oil change or check or whatever, and lot's of smoke as cover was just open before to check apparently. I do not hear any weird noise but please do not hesitate to give comments
https://youtu.be/Hfv5B5krpyM

sidetracking a bit : is #4 trumpet shorter on purpose ?

nmauduit wrote:sidetracking a bit : is #4 trumpet shorter on purpose ?

Excellent question
Not sure if it is stock like that, but apparently fewer air was entering in the last trumpet due to airbox configuration and having a shortened one was helping to have a proper air intake repartition.
But expert would probably answer better than me

Just another observation, the carbs fitted in the video are not the original type fitted to an Elan. Judging from the tall top caps, and the auxiliary venturi's that are fitted, they are more than likely Tipo 34 / 35's , or 90/91's, original equipment on a 1725cc Hillman Hunter GLS or Sunbeam Rapier H120.
If I'm right, the carbs will not have a float chamber breather hole at the front of the carburettor body.
These carbs breathe through a weird castellated spacer fitted underneath the top cap.

They will work, but never as well as the Tipo 18's, or 31's that were originally fitted to the Lotus T/C.

I've seen the shorter ram pipe on number 4 cylinder many times on theT/C, some versions of the airbox were shaped (tapered) on the back of the airbox to enable fitment in certain applications.

It actually sounds quite good. If I were you, I'd get rid of the oil that's external and making the smoke, change the oil and filter, make sure you've got the correct oil pessure, and run it before stripping it down. Run it for half an hour, and see what you've got when the engine is hot, idle oil pressure and pressure at 3000 rpm..
If these are ok, then concentrate on your other issues first, you may not need to spend as much money on the motor as you first thought.....
At some point it would be good to change the carbs back to DCOE 31's though.

Thanks you both,

Carb have to be change or just tipo ?

I will not strip the engine down yet (a lot more to do with the body, subframe and rolling elements ).

But As I will soon remove the shell I will have all the access needed to clean and check, I still may want to change oil and filter to indeed test it before to move shell and dashboard to check for what instrument are still working (didn't attach a battery yet … a bit afraid of starting a fire )

NB: Any Idea why previous owner may have change the carb ?

Newsax wrote:Thanks you both,

Carb have to be change or just tipo ?

I will not strip the engine down yet (a lot more to do with the body, subframe and rolling elements ).

But As I will soon remove the shell I will have all the access needed to clean and check, I still may want to change oil and filter to indeed test it before to move shell and dashboard to check for what instrument are still working (didn't attach a battery yet … a bit afraid of starting a fire )

NB: Any Idea why previous owner may have change the carb ?

You may first double check if indeed they are type 34/35 (no venting on the engine side), and if so make sure that the castellated rings are in place. I'm running my street S4se with that kind of carbs (covers had been changed at some point, which tricked me for a while), I believe you may obtain a quite decent state of tune if all is right otherwise (general condition and leaks, jetting, timing etc plus I would suspect identical trumpets would have to be installed first, to avoid an unbalance at revs), then when the car has been brought to the condition you wishes you'll have time to consider swapping to 40DCOE31...

Newsax wrote:Thanks you both,

Carb have to be change or just tipo ?

I will not strip the engine down yet (a lot more to do with the body, subframe and rolling elements ).

But As I will soon remove the shell I will have all the access needed to clean and check, I still may want to change oil and filter to indeed test it before to move shell and dashboard to check for what instrument are still working (didn't attach a battery yet … a bit afraid of starting a fire )

NB: Any Idea why previous owner may have change the carb ?

The whole carburettor set will have to be changed, especially if you confirm that they have no breather hole in the front of the body casting.
No idea why they have been changed, except that the 34/35 or 90 / 91 tend to be cheaper on the second hand market.
As I said before, you may well get them to run ok, but they won't ever be as good as the 31's, as they have different progression hole positioning, and from memory have different accelerator pump stroke length also.
The Tipo" is the model number, and is mostly specific to a manufacturer / engine, so they have the progression holes drilled in a specific place, different accelerator pump stroke lengths, different jets, different float setting heights etc, even down to the interconnecting linkages.
The exceptions to this rule are the 40 DCOE 18, (originally fitted to the Twincam, but became the go-to carb in the 60's and 70's for aftermarket fitting to most makes of engine), the 40 DCOE 2, fitted as OE to early Twincam and some Alfa Romeo), and latterly the 40 DCOE 151, which again became the generic carb for tuning after the others went out of production.

My thoughts..
As others have said it doesn't sound too bad really and although it depends of course what the end result is you are trying to achieve with both the car and engine I would have thought it was worth trying to investigate first what you have without immediately throwing serious money at it.
There are no serious knocks coming from the engine and I would agree it definitely has carburettor issues it also has a misfire at low revs and is not running on all 4cylinders properly which I personally do not think is all down to the carburettors.
So the first thing I would do is a cylinder compression test which will tell you a lot about the state of the engine. Also I would try and stop whatever is causing the oily smoke, possibly cam cover gasket, then fit a new set of spark plugs and see what it runs like then before going any further.
Once you start taking the cylinder head off and stripping there will be no going back and things will get expensive!!


Alan.

Maybe ask Arno Huberts (Arno I think on here) he’s the Dutch Caterham man I’m sure he would have contacts and he’s probably 2.5 hours from you.??

Yves, I have sent a message about your query.
Malcolm

Hello Yves

To answer your question, you should try this firm: https://www.roadraceltd.com/ateliers/ in Verviers.

I believe that Roger Poulet has his race engines built by these folks.

Andrew

Thanks for all the advices ! and for the adress Frogelan !
I will follow your advice, even if I have no Idea where to find the second hand carburator you mentionned and the price of it

elans3 wrote:
The whole carburettor set will have to be changed, especially if you confirm that they have no breather hole in the front of the body casting.

I will make a closer video so you can confirm, or maybe some ref number will confirm that ?

Those are the corresponding ones ?