advance/retard pipe

[Stoneporch]

I've just bought an Accuspark unit, which comes complete with A/R diaphragm. Only now have I realised that my old distributor did not have this A/R thing connected and that there seems nowhere on the carb for a take-off. Can anyone please tell me how to rectify this....must the carb be drilled somewhere and a tube fitted?? The car is fitted with a1300 Marina engine, (which is sluggish to say the least).Thanks.

[bmcecosse]

What carb is on the engine? Does it have a diagonal - or square flange to the manifold? If there is a phenolic spacer between carb and manifold - you can drill a hole through and bond in a stub pipe..

[Stoneporch]

Right, thanks for the reply.
As my car is currently away at the local mending emporium, I will have to go over and check those points.
My Midget-engined traveller has a pipe coming out of the carb body near the slow-running adjustment screw, and I notice that the other carb has an identical mark in the casting (but no hole). Would it be feasible to drill a hole at this point on my Marina carb....taking care to clean thoroughly afterwards, of course? Or perhaps it's safer to fit and drill a spacer?

[bmcecosse]

You can try... but the spacer is pretty easy to do.

[simmitc]

The pipe near the adjusting screw is probably about 1/4 inch diameter, in which case it is to suck fumes out of the breathing system. The A/R vacuum takeoff is usually a little spigot near the float chamber. As above, easy to fit a small pipe into the spacer.

[philthehill]

If I remember correctly some of the 1275cc Marina engines had the vacuum advance and retard removed because with the vacuum advance fitted it induced a rumble at the bottom end of the engine. With the vacuum advance removed the rumble disappeared.

[bmcecosse]

And I've never been able to understand that one !

[Stoneporch]

Thanks all.
My car certainly doesn't rumble from the bottom-but neither could it remove rice pudding skin with any alacrity! I had hoped that by engaging the A/R it would be a little more lively.
I think we will try and obtain an appropriate diagonal spacer and see whether connecting the A/R does offer any improvement.
Thanks again for those thoughts, folks.
PS. ..I was surprised not to be able to find any reference to the vacuum pipe in the Haynes or BMC manuals.

[philthehill]

Chapter 4 - Ignition System - Haynes Marina wksp manual No: 073 has comprehensive details of the distributer both with vacuum advance (distributer 25D4) and without vacuum advance (distributer 23D4).
The serial type numbers of the distributer are:- HC 41372 & LC 41234.
What distributer did you have fitted?
Later engines had the 43D4 & 45D4 distributers fitted (see supplement at rear of Haynes wksp manual)
I suspect that you have the low compression engine fitted.
What is the engine number?
Have you checked the individual cylinder compressions as that will tell a lot about the engine.
The Pt No: of the vacuum advance pipe is 37H 4229M and the connector is Pt No: 12B 2095 (straight) or Pt No: 12B 2062 (angled) and according to the BL parts list should fit (if fitted) onto/into the R/H side of the carb when looking from the carb towards the engine. Is there a connection that has been blanked off or covered with a rubber plug?
Phil

[bmcecosse]

A working vacuum advance - with the correct mechanical advance curve inside the dizzy - should indeed 'brighten' the engine. As Phil suggests - check the compressions ! Check and set the valve gaps first (12thou inlets/15 thou exhausts) and then set up the timing to 'not quite pinking'. Is the air filter element nice and clean ??