If your Flat 4 engine is suffering from spluttering and flat spots it could be because of carburettor icing. This is particularly common on engines with a standard single Solex, as due to its positioning, it doesn’t benefit from the heat generated by the cylinder heads.
Heat is important to the combustion process as it assists with the atomising of the fuel and also prevents any water vapour in the air freezing.
VW engineered a number of ways to fix this issue including heat riser pipes, which draw warm air from the exhaust up alongside the manifold, and warm air feeds directly into the air cleaner, but sadly both lose their effectiveness over time.
Whilst owners today can retrace any of the above steps to make improvements, another alternative is fitting ‘an electric blanket’ to the manifold base. The IMDU (Inlet Manifold De-icing unit) is a quick DIY fit and should tackle your frustrating running issues without spending hours in the garage.
Priced at £35.95 you can find them at heritagepartscentre.com by searching for IMDU, alternatively give their team of friendly enthusiasts a call on 01273 444000 and they’ll get one in the post ASAP for you.