In the first of a series of “how to” pages we hope to bring you, a quick write up on how simple it is to rebuild the Dellorto or Weber Sidedraft carbies.

First off, get together all the things you’ll need. These include large and small screwdrivers, a set of sockets, pliers, Stanley knife, rebuild kits, penetrating lubricant (WD40, Penetrene, CRC etc), carby cleaner (about a can per carb)steel wool and rags.

You will need

Your rebuild kit will probably include an assortment of “o” rings, needle and seat, gaskets cut to size, pump diaphragm, and crush washers. Ours did…

Give the outside a good spray with carby cleaner and a bit of a scrub with a toothbrush or dish brush. The cleaner will kill grass so its a good idea to convince the boss that you’re doing them a favour by killing the weeds at the same time.

Take off the jet cover and fuel rail, then the float roof and floats can be removed. Push the pin towards the ‘split’ end, we used a fine punch (read rivet) and a small hammer to persuade it gently. Clean it all with carbie cleaner, and give any corroded bits a polish with the steel wool and a bit of penetrene. Make sure that you don’t leave any steel filings behind, because your head flow figures will never be the same again…

Next we turned it downside-up and took off the pump and the next bit, gave the whole mechanism a tub up and replaced the diaphragm with the new one in the kit.

Go for the seat, it’s in the roof of the float bowl. We got a new one in the kit, but we didn’t get a new filter and the old one wouldn’t fit with the new seat, it just crushed up when we screwed it in, causing a possible logjam, so we left it out. I would have liked to leave it in. In the picture below, it’s the plastic piece plugged into the brass bit Juice is holding.

The needle is matched to the seat, so it too was replaced. The top hooks into the floats and sits in the seat, then the float pivot pin is replaced from the ‘split’ end. The float height is checked, the right heights were contained with the kits. for our 40mm’s we were given 14.5mm. They were already pretty close so we left them.

Grab the venturis out by undoing the small screw on the side and some penetrant to loosen them up. Clean the accumulated gum off them with the steel wool and Penetrene, then a polish with carby cleaner and a rag. When we replaced them we added a thin layer of copper anti-seize grease around the outside to stop them sticking in the future.

We pulled out most of the screws that wanted to come out, and just cleaned up the threads with carby cleaner.  The o rings were all replaced and then returned.

Then the float roof and pump housings were screwed back onto the top and bottom respectively, and the final gaskets were replaced over the jets (which had been hit with carby cleaner and high pressure air).

And voila! One clean Dellorto sidedraft carby. Now to do the other one! They should take about 90 minutes a piece, we took our time with the first one and bowled through the second one in no time. If you have any questions, shoot an email to and I’ll try to help.

My last pearl of wisdom for today, don’t get carby cleaner in your eyes. the next door neighbors kids will laugh at you over the fence.


20 Responses to “How to: Rebuild Dellorto Sidedrafts”

  1. Bryony Says:

    Nice and sparkly, but still can’t see the view.

  2. I’m often looking for brandnew infos in the WWW about this issue. Thanx!!

  3. david Says:

    about to give this a go, thanks for your write up, its been the best one i can find so far!

  4. Bobby Says:

    Hi thanks for this posting it is quite helpful for a complete novice like me I am gathering the courage to build my triple dellorto’s after a couple of clowns took them apart and never repaired them and left them in pieces for me even though I told them not to do it if they cannot get the overhaul kits,anyway rant aside I will probaby lean on your expertise as I am fed up with people not doing what they are paid to do and I will try myself.
    These are for my Datsun 240Z and will post up piccies as I cannot remember what they are 40/45?

  5. manzinilox Says:

    Should be the same process whether 40 or 45. It really was pretty simple if you’re methodical about it. This was the first time I’d taken a carbie apart, and it went back together with very few parts left over!
    Post pictures and drop us a link!

  6. Michael Says:

    Thanks for the posting, very helpful. Just got my rebuilding kits today!

  7. Nick Says:

    Thanks for putting this on-line. Gave me useful narrative to go with the Dellorto fact sheet. The biggest nuisance was getting the pump jets in after cleaning/inspection. I pressed and turned them with the end of a paperclip before they’d seat properly – if you don’t get ’em right then you can’t screw them home. My float height was too wide – easily bent to correct clearence! All running now. Nick 🙂

  8. […] Porsche lineup ranks slightly below the Turkmenistani tax code and the rebuild instructions for a Dell’Orto carburetor among maddeningly complex foreign things. To wit: the four-wheel-drive 911, the Carrera 4. The next […]

  9. […] all the jets + replaced the gaskets and diaphram. I got some useful advice from the posting The only problem I encountered was with the pump jets which you have to get in the right position […]

  10. mel Says:

    I have 6 orings and no idea where they go

  11. AJ Says:

    yup i got the carby clearner in the eye too…

  12. josh Says:

    Hi, do you know how to remove the choke piston?

  13. i love this thread, and now so does my ae86, “we will be more careful with our eyes! erm, next time!!!” hahaha wait till u get stale fuel in your eyes! hahahaha peace and respect!

  14. Aaron Says:

    Great write up however you should never use copper slip with any aluminium because copper and ally react so will sieze and ruin your carb’s……..

  15. avinash Says:

    My rev on my dellorto 40mm sidedraft does not want to drop when my car is at running temperature I tried everything please help

    • manzinilox Says:

      Hi, we had the same problem after the rebuild. It was caused by a piece of junk in the needle and seat which made an uncontrolled fuel dribble. Check your fuel circuit carefully of blockages or obstructions.

      If it only does this at temp, it also sounds like it could be a choke problem. We disconnected the choke circuit all together, and we have never had an issue starting it cold. But Melbourne cold is very different to real cold found elsewhere.


        Hi thanks for the advice but I don’t really know a lot about sidedrafts this is the first time I installed one so can you explain to me where is the needle and seat also how do I disconnect the choke?

    • Gregory Says:

      Do you have any idea what my problem could be. I using 48 Dellorto on Mazda RX7 !3B engine. rebuilt carb last summer, worked fine except millage was high. This year having much trouble. have tried many float levels 13.5mm to 17mm Ideal circuit does not seem to work at all .engine seem to run only on accelerator pump. No ideal no steady running

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