I have recently restored my 36 HP 1960 beetle, although I didn't touch the engine. Now when I drive below 15 degrees,
at 65 mph I coughs until I back off the throttle. The top of the inlet manifold & the base of the carb have iced up. The bottom of the manifold is warm on both sides, indicating that the exhaust heating tube isn't blocked. The only thing different is the engine bay rubbers have been replaced and now seal properly. Coming home tonight with tape blocking
3/4 of the air vent. It run fine. Why is it getting so cold?

try starting your engine. letting it run for a few minutes and then shutting it off. letting the warmth from the engine de ice the manafold and then start it again and it shouldnt ice up again. i used to have the same problem with my baja when i was living in a colder area.

I think possibly the manifold heater pipe IS blocked... it should be too hot to touch

They get blocked with carbon and coke deposits.

Hey John, do have a stock exhaust?

Giddaye Brad,

Yes it has a NOS Genuine German VW muffler, likewise for the inlet manifold. It's only done 150 miles since fitting them so I doubt they've had time to carbon up. Plus both sides of the bottom are hot. It has no Automatic cooling air control on the fan housing, but it hasn't had one in the 10 years I've had it.

Hi John, the manifold should be hot to touch if its working properly. It will get warm on the ends from heat transfer from the exhaust but not enough to stop the icing if the motor is prone to this. (they dont all do it for some strange reason) The other way to cure this is use a heating element that wraps around the manifold. The VW Performance Center in Croydon have these. I used one on my Grey Oval to cure manifold icing. Simple fit and connects to the + coil wire.

Thanks Dean

Were you still running 6 volts?

No I was ruinning 12 volts but these units are available in 6 or 12 volt.