Lotus Elan and Lotus Elan Plus 2 Forums

Hi can anyone tell me the thread size of the vacuum ports or better still where I can buy a take of pipe to attach to a set of vacuum guages

Thanks steve

After some google searching I believe it's an m5 thread. Does anybody else have experience using davida vacuum gauges to balance weber 40 dcoe carbs.

Steve

I used a JJC flow meter instead.



See
lotus-elan-f19/getting-ogu-roadworthy-again-t26101-105.html#p191111

steve please tell me where the vacuum ports are.
I thought they were only on Dellortos

Depends upon which version of Webers you are referring to. 18's don't have any take off - 151's do.

Regards
Richard

thanks, the 151's are replacement carbs and not original equipement and have a balance drilling between the 2 venturis

Concrete-crusher wrote:After some google searching I believe it's an m5 thread. Does anybody else have experience using davida vacuum gauges to balance weber 40 dcoe carbs.

Steve

Yes, Steve, M5 threads. I've not used Davida gauges as they are rather expensive but have had good result from Busters EVG4 Economy System 4 Vac Gauges for ?55 delivered. They needed adjusting to get the needles to zero but I checked them for scaling and they were identical. They are ready to attach to a pair of Weber 151s and have revolutionised setting my car up, it's so easy now.

PM me if you need to know how I calibrated them; meanwhile this is what they look like in action (before I balanced the carbs).

I use this on 151's. Mike

http://www.carbtune.co.uk/index.html

i believe, still. No-one is drilling ports, on 31's

h20hamelan wrote:i believe, still. No-one is drilling ports, on 31's

I think if you want to measure vacuum when using Weber 18s or 31s then the solution is to drill and tap into the inlet manifold rather than the carburettor bodies.

If you’re brave enough......Personally, I’d rather replace the carbs.

Regards
Richard

"If you’re brave enough......Personally, I’d rather replace the carbs."
To be honest it's more if you're RICHard enough
Alan

I think I have them very close, I will try a few more things first.

Anyone want to comment if balancing in this way is worth it. Nothing to do with drilling and tapping etc...
Or, how many 31 owners who have switched, noticed marked difference?

h20hamelan wrote:I think I have them very close, I will try a few more things first.

Anyone want to comment if balancing in this way is worth it. Nothing to do with drilling and tapping etc...
Or, how many 31 owners who have switched, noticed marked difference?

As I stated above, a great improvement and gives great confidence.

I tapped all the inlets in the middle of a casting mark, on my first rebuild in about 1970 when I had 18s, and usually just stopped them up with tailored screws. I drilled thin holes through four short brass rods which I threaded on one end and stuck a rubber tube on the other, but I only had a single gauge so pushed a tapered plug in the three not being measured. It was unsatisfactory and I hardly ever did it, but with a cheap quad gauge like mine I recommend it.

For me the best and easiest is with a "Carbtune".
Alan

alan.barker wrote:For me the best and easiest is with a "Carbtune".
Alan

+1 to that!!