Lotus Elan and Lotus Elan Plus 2 Forums

I have just recieved a manometer to synch my carbs, it works perfectly, however it shows a significant discprepency between what I expected from my carbs, what the manual says and the results on my dellorto's;

the vacuum generated by the carbs demonstrated that they were well off synch,
I won't get into flow rates but the readings were as follows:
cyl1 verrrry low...almost not registering a vacuum at all (I have blocked the light pod vacuum tube off the inlet manifold to try to fix this)
cyl2 highest
cyl3 low
cyl4 high

according to the manual I should balance the lowest value on the one carb with the lowest value on the other (cyl1 & cyl3 for me), if I do this the engine gets very rough and is close to stalling.

If i balance the carbs using the highest setting on one versus the highest on the other (cyl2 & cyl4), then it all makes sense, a small adjustment and they match up perfectly and engine runs well.

but the manual then says that I should use the "bypass screws" to even all the values.......where are they !!!! i have looked all over and cannot find them anywhere, no online dellorto manual or the Lotus manual identifies them, can someone here help me. At the moment cyl 2 and 4 are matched, cyl 3 and 1 are matched, but now I need to even them across all barrels.... :unsure:

i found this problem a while ago,it seems that the "later" versions have these balance screws.
us poor relatives have to put up with slightly "bending" the bar holding the butterfly plates
John

The first series of DHLA 40 carbs (with apparent and bigger richness screws) do not have these balancing screws ; only the later versions with the smaller richness adjusting screws have them.
I prefer to use the "old " balancing system device (vacuum body with a ball moving into a transparent sleeve) connected to the inlet port of the carbs and this works very fine.
It works also fine on my motorbike and I get a better tuning than with the actual system (with hoses) !
The only problem we have is that we cannot balance the bodies separately as I do on my motorbike (as you know, the "vacuum" is related to many elements and you cannot get with an old engine the same values on every cylinder).
So do not expect a perfect balancing if you have uneven compressions !

Edouard de Grand Ry
SE SE 1969