SU Carbs

In between Christmas festive events, I put together a list of things that I wanted to look at. One of them is the engine airflow. When accelerating, the car pushes decently up to 3 krpm and then, it suffers from asthma…

Frosch came with some SU thin chrome air filter directly mounted to the HS2 housing; the inlet flow should be improved replacing these tiny filters with a set of ram pipes purchased from Minispares. And as I was going to play with the carbs, I decided to fit new fuel lines too...

When I first opened the box of goodies, I was a little puzzled with the ram pipe design; for some reason, the mounting holes of these pipes are threaded and I am not sure what the intention was. 😵

As the SU carb holes are threaded, I decided to drill out the ram pipe threaded holes to an "elongated clearance fit" (8x9mm) which allows for a small amount of fitting flexibility. To clear the bolt heads, the sides of each pipe were ground a little.

When putting apart the chrome filters, I found that the HS2s were mated with HS1 gaskets – 1 ⅛” dia instead of 1 ¼” dia 😱.

The flow was not streamlined, it was also restricted too… The ram pipe and the correct gasket should improve this.

While mating the ram pipes to the carbs, I checked that the mouths of the pipe and carb aligned smoothly hence the elongated holes mentioned earlier.

Et voila... 

 

...with the RAMAIR Filters and the new fuel lines!

Since the bonnet was up, the radiator coolant hoses were swapped for a new silicone set, new BMW spec-compliant coolant was poured into the system and a new 7Lbs rad cap was fitted (the old one was 4Lbs as fitted on Austin Healey 100).

Why BMW coolant??? simple, I had a bottle left sitting doing nothing. On other cars including the elise race car I normally use VAG G12/G13 coolant.