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.
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 firstname.lastname@example.org 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.