Synopsis:
Changed the weber 36 DCA 5/250 for another that was clean and overhauled (they are a simple carb easy to check all passages etc).
New carb would not run properly. It would start fine from cold but as soon as the engine got any warmth it died (at tick over).
Firstly suspected an air leak at the manifold - brake cleaner increased revs but could have been sucked in as running with no air cleaner (is this the problem....
running with no air cleaner?)
Removed carb and carefully replaced base gasket and used a smear of silicon refitting the carb. No different.
Put old carb back - same issues would start, rev cleanly but die at tickover even with the throttle stop screwed in.
Closed off all vacuum pipes (servo, distributor, carb water heater valve) - no difference
Measured fuel pressure - seemed a bit random 2-3psi (I have fitted a malpassi fuel regulator in place of the 2 Lancia "regulators" but it could for some reason not regulate). I have linked out the thermoswitch fuel limiting device just in case that was causing something
Did open pipe flow measurement of fuel pump (Bosch original) and got c 125 lph reading, also it read 3bar (only connected to a high pressure gauge nothing else). A Chinese copy which I had on the shelf did twice that.
Decided to buy another Bosch (Chinese copy does not seem to have built in one way valve). Fitted today. Same running issue remains but now I have a controllable pressure at Carb - set to 3psi.
Pulled plugs and they seem ok if a bit white on the central electrode. Checked timing (Valve and ignition both OK)
The auto choke works as it should, and float level is spec
It starts easy from cold, revs well but is splashy when throttle reduces. Just will not tick over - best I can do 1500 but its hardly steady and sometimes dies without warning.
At wits end... Is it the air cleaner???
