U20 + Webers, what manifold?

[TeemuM]

I am rebuilding my U20 during winter and thinking of getting pair of Weber 45´s.
Is there any aftermarket manifold that fit to U20?

There seems to be options for R16 and L-engines, but I assume that those don´t fit to U20?

[fj20spl311]

Only the factory solex manifold. Some of the members and vendors have toyed with the idea of making copies.

[TeemuM]

Is there much difference between R16 or L-engine port spacing compared to U20?
So is it possible to cut flange from manifold that is meant for R16 and weld new one that fits to U20?

If anyone has these dimensions for R16 or L16-20 engine I really appreciate it.

[greydog]

Disclaimer...I have no direct experience with attempting this...
I have seen the Cannon manifold on both R16's and L20's.
The manifold castings are of very poor quality. Having been in the metals business for more then 40 years, I'd be very concerned with trying to weld these castings and retain any sort of alignment. longevity, integrity.
Still, given enough talent and time, most anything can be done.
When a poster on this site began his research into a fabricated manifold, I believe the expert opinion was that reworking a stock cast manifold was impractical and that fabricating one was not cost effective in low production quantities.
As prices increase for a limited supply of factory maifolds, a fabricated solution may become viable but it's not likely to make using a rough casting any more practical.
We have some true experts on this site, I'm sure they'll chime in.
Dan

[SLOroadster]

An L series won't work, the head ports are in very different places. The only manifold that does work (short of building your own) is the factory one. That said, Webers don't work well either since the actuate backward from the Mikunis. Also, why waste the time with Webers when Mikunis are better carbs anyway? Using an R series manifold is not really an option either since the ports are much smaller (even if you could get it to actually bolt onto the head.)

Will

[spl310]

There were folks chopping up the U20 manifolds to put them on the L motors back in the day. All that they did is split the manifold and adjust the width iirc. If that is the case, you could do the same thing with an aftermarket L manifold, you would just have to plug the coolant passages.

[TeemuM]

An L series won't work, the head ports are in very different places. The only manifold that does work (short of building your own) is the factory one. That said, Webers don't work well either since the actuate backward from the Mikunis. Also, why waste the time with Webers when Mikunis are better carbs anyway? Using an R series manifold is not really an option either since the ports are much smaller (even if you could get it to actually bolt onto the head.)

Will

Ok, thanks for info! I quess I will need to build my own manifold as factory ones are out of my price range.

Reason for Webers is only that we have local vendor that sells Webers. I thought it would be good to have some local customer support as all cars that I have build I have used aftermarket ECU so I have zero experience tuning carbs. But I am not fixed to use Webers if Mikunis are better.

Does anyone have any pictures of DIY manifolds?

[spl310]

I haven't seen any DIY manifolds for a U20. I have one for an R16 that I posted on here a while back. There are plenty of people who run Webers on all sorts of cars and are quite happy with them. If you are having to fabricate, I would certainly go weber as they are available and much less expensive than Mikunis. The value of Mikunis has jumped recently.

[Alvin]

You can use the factory, U20 manifold to run Webers:

[theunz]

Every few years someone comes up with big plans to build their own manifold. Haven't seen one materialize yet! Racers seem to make the SU's work fine.

[cktrap]

Ah, but the sound
Keith

[TeemuM]

Slow day at work so had time to think about this. Found bended aluminium tubes from local shop which were just about right dimension for that. Needs little bit of porting after welding but that is thick walled tube so there is enough material to work with.

Red lines are porting that need to be done to flanges and yellow is porting that is done to pipe. Those sharp angles between tube and flange can be rounded after welding. I need to get those flanges cutted from thick material so I can mill it straight after welding.

Need to measure those port dimensions this weekend from my engine as those flange dimensions and carb 3D models were just something that I found online. Also need to start design how to mount linkage etc but I think this is doable.

[Pjackb]

Please see this thread and get in touch with BBF Roadster

viewtopic.php?f=61&t=29513

And since you’re in Europe have you thought of these ? I know they’re very high on my bucket list

http://omextechnology.co.uk/Omex%20Gene ... 0v4_40.pdf

[TeemuM]

Now that my car is getting closer to be in driving condition I started to look again intake manifold options for twin carbs. I asked quote for aluminium 3D print but it was way too expensive as expected. About 1000€ / piece. And this was not in one piece as original Solex manifold to get price down so total would be 2000€+water pipe that I left out at this point.

So at this time printing is not option but maybe in future when prices get down.

I quess I need to start learning sand casting.

[JT68]

We can set you up Teemu. We have webers and solexes too. Just PM or Email//