Lotus Elan Weber 40 DCOE Home Rebuild or Not?

[djb222]

Whilst waiting for the primer in the engine bay to dry, I thought I'd show you the condition of the Weber 40 DCOE's fitted to my car.
They are the original type 31 carbs and look in need of a full refurb, now the question is do I buy all the jets to rebuild and clean them myself or farm the job out to a specialist....hmmmmmm. Sounds like a nice job to me especially as the winter nights are looming. What do you think? Any advice from those who have tackled the job before?
There is a mistake part way through duh..... can you spot it?

https://youtu.be/pJfTLuCL7P4

[RichC]

the most rewarding job i found on a pair of the same vintage as yours was unblocking the progression channels which were silted up with what resembled cement ( concreted sand). i used a fine drill and then replaced the lead capping with a new bit of lead which was cold peened in place . What a professional would charge for such a job I'd hate to think ....
the actuation of accelerator pump needs to be working smoothly ... when i pulled mine apart, one was on the slow side as it had completely seized and corrosion was very bad when removed and it took a lot of cleaning up to get it almost right .... It was never perfect so i swapped in a new pair of webers instead.
might be cheaper for you in long run if you find your webers are too far gone

[shaun]

Rebuilt a few dcoe Weber?s , its a very time consuming and expensive job but well worth tackling yourself

[shaun]

Just waiting for a few more items to finish

[Craven]

I have refurbished probably 10 pairs or so of 40?s in my time and unless you know your carbs are low mileage my advice is to buy new. 31?s on a Lotus T/C was a disaster anyway.
Many of the faults people have ie leaks/drips are the result of just simply worn out carb?s.
FWIW.

[djb222]

Thanks for the advice.
I'm not sure whether the carbs have been rebuilt at any time in its 110k mile history, however the head although it has the SE cams has the bigger inlet valves and has been ported, so I suspect they have, albeit many years ago.

I would like to retain the carbs and will try and rebuild them, knowing help or new ones are easy to find.

Why do you say 31's aren't suited to a Twincam?

[Craven]

Plenty written on the problems with 31?s on this site. Lotus attempted to overcome the fact the progression is to far forward or advanced on 31?s to provide correct mixture at tickover and slightly beyond, far too rich.
A small hole was drilled in the lower section of the butterfly to try and reduce over rich mix by introducing extra air, worked when engines were new but failed to compensate later.
Progression holes are one of the few parameters that are not variable, yes progression can be advanced or retarded but in the case of 31?s they are too far out.
It amazes me why people think shiny carb?s equal good condition.

[djb222]

Thanks Craven, I'll certainly have a read of the threads. I would certainly hope that any effort spent cleaning a set af carbs would indicate the same attention given to the internals.

[Craven]

You can?t improve worn out parts by cleaning!!
Cheers.

[djb222]

That, I would have thought would go without saying!

[Craven]

Good luck with your refurbishment let us know how your engine runs when complete.

[djb222]

Thanks, I hope to have it ready for next Spring......at least that's the plan.

[Grizzly]

I'm with Craven on this, i have had real issues with my Dcoe's and they were rebuilt by Webcon at great cost (they were vapor blasted too so looked really nice when i first got them back), i was a bit dazzled by how good they look after a rebuild so persevered way more than i probably should have and my thinking was they had only covered 40,000 miles since new so can't have been that worn........

Looking back now i wish i had just replaced them rather than rebuilt them.

When all said and done i guess it depends on what your idea of acceptable is, my car starts and drives ok but ok is as good as it gets even after 3 rolling road sessions. I am planning on fitting the Keith Francks kit in the new year but i suspect that will be like lipstick on a pig.

[prezoom]

Most leaks and drips in 40mm Webers can be the result of the auxiliary venturi not being fitted tightly enough against the fuel transfer port in the carbs body. The wire spring P clip that secures the venturi is not strong enough to create enough pressure to make a good seal. The 45mm Webers make use of a grub screw and a locking nut in lieu of the weak P clip, which permits sufficient pressure to be exerted to mostly prevent leaking in this area. I used an arch punch to cut a small round bit of rubber sheet, then inserted it in the loop of the P clip to increase the pressure of the venturi agains the carb body. I then cut a strip of the same sheet that fit snugly in the machined slot from the front face of the carbs to as far as it would go alongside of the venturi and the air horn. This does make removing the auxiliary venture a bit more difficult, if you are changing the primary venturi sizes. So far, since 2006, I have no more leaks from the carbs. Wish I had been smarter about this back in 1965, when the Webers on my S7 leaked like an old faucet. The 45's on my Plus2, which have the grub screws are always dry.

[denicholls2]

While the Weber experts are paying attention, I have a pair of DCOE-40's that I believe came from a LoCort. The chokes are positioned in the bodies by little pieces of spring steel which I've never been able to name or locate on the web -- they may only go on earlier units as the diagrams I've seen don't seem to have them.

Anyway, I need a few of these to make the carbs whole. Anybody know of a source?