Chevette Owners Group

Non Members Area => General Discussion => Topic started by: Karlcarron on May 29, 2017, 22:46:25

Title: What the best carb to use
Post by: Karlcarron on May 29, 2017, 22:46:25
Hi I've got a standard carb on my 1.3 engine it seems to lose the oil when topped up only lasts about 3 days. I wanted to see what ppl are useing and can I still use my standard inlet cheers Karl
Title: Re: What the best carb to use
Post by: scotty on May 30, 2017, 10:06:06
Lots of people have used  Webers both side and downdraft. You need a different inlet manifold to fit them though. The manifolds are getting rare. - Scotty
Title: Re: What the best carb to use
Post by: Jeff J on May 30, 2017, 13:26:15
What is your current carb & why can you not repair it?
Title: Re: What the best carb to use
Post by: scotty on May 30, 2017, 18:48:32
If your car is driving ok I wouldn't worry about the oil in the dashpot at all. Its only function is to slow the rise of the piston down a bit to stop sudden mixture variations. You don't need to use engine oil either hydraulic fluid or automatic transmission fluid work too. Depending on the viscosity you get different rates of piston damping. Its all a bit marginal really and not worth worrying about. What is important is to ensure that the carb diaphragm is intact as if it splits the mixture gets really messed up and the car will run really rough.   Hope this helps - Scotty
Title: Re: What the best carb to use
Post by: Bill on May 31, 2017, 13:35:29
the dashpot only holds a little oil, excess is pushed out when the piston rises.

it's purpose as scotty said is to dampen the rise of the piston under acceleration.

Without the oil and damper the piston would fly up if you hit the throttle hard and the engine wouldn't accelerate as the air / fuel mixture would bottom out. It would basically stall.

the damping means the piston cannot rise fast, so under fast throttle movement downwards the increased vacuum would suck more fuel from the carb as the piston rises slowly causing a richer mixture, what you need when booting it :)  The damper is 1 way via the plunger gizmo so when you let off the piston falls to where it needs to be .

The only way the oil disappears completely is if the rubber O ring around the needle jet has perished which is very possible after 30+ years.

Zenithcarb.co.uk do service kits and parts of needed.

to be honest in good condition the CD carb is a very dependable beast and the biggest issue is common amongst all carbs on the chevette , that is fuel vaporisation from having it above the exhaust manifold when hot.

I have driven 34k+ miles in the last 2 years with one :)

I think there is some carb refurb info in the workshop forums on here too. Visible to members.

Bill

Title: Re: What the best carb to use
Post by: Karlcarron on Jun 20, 2017, 18:41:15
All sorted now Thanks it's a zenith carb the oring had gone hard so replaced that also the tank has started to give off rust so blocked up the carb so new tank being made so hoping should be running nice has anyone used a k n filter like this. If so just seeing what you did with the vac pipes cheers Karl
Title: Re: What the best carb to use
Post by: Bill on Aug 15, 2017, 17:44:56
those filters i have seen used.  you may also be able to get a standard K&N filter for the original filter box. it may give you better flow than that one and you retain the breather setup.

They are reusable/washable etc..  the oil vapour from the rocker is convenient at re-oiling cleaned filters too :D

look out on ebay as k&n have stopped making them

Bill