Car in bits again...
AO Silver Member
Join Date: Feb 2007
Location: Hampshire, UK
Alfa 1.5 twin carb "misfire" - instant diagnosis?
Hi there Boxer fans - I have a 1.5 Green Cloverleaf engine fitted in the Green Machine, but it is showing signs of what feels like a misfire. However, the symptoms are quite specific and I wonder what the collective view is on where I should be looking...
The engine has been sitting in storage for 20 years, and now has 1300 miles on the clock. Standard 95 horse with 36 IDF's. I didn't have an electronic ignition module, so the distributor is a Bosch points unit I got off my 1978 Ti 1.5. I replaced the coil a while back, but it could be faulty. Equally the condenser could have failed and the points have got burned. But equally the problem could be fuel related; the misfire is not evident under hard acceleration, or small throttle openings in high gear (5th gear around town for instance). I've got a Filter King regulator/filter in the fuel line and an electric pump because my chassis design didn't allow room for the mechanical pump. Pressure is around 2-2.5 psi as I believe Webers don't like a lot of pressure.
At around 30 mph in 3rd this sortof "missing" starts and only eases off if I try and accelerate through it. Plugs are the original Lodge items, ignition leads are factory originals apart from the coil lead.
So, it could be fuel (blocked intermediate jet, maybe?), it could be iginition (plugs/points/leads/coil/condenser?), I just wondered with your greater combined experience of driving this unit, where should I be looking first?
All suggestions gratefully received - Green Machine attracts a lot of attention and having a mis-fire is getting a little embarrassing...