Hissing Air intake

[winger300]

Car seems to be running pretty well now. I replaced the HS4 carb with a HIF38, so no more fuel leaks hopefully.

Anyway, the hissing / whistle sound i mentioned before is still there. Im pretty sure there are no air leaks, and this new HIF38 carb has a solid butterfly valve, so thats not the problem.

The hissing sound is just at the point before you start to hear the induction roar. I have one of the cone type K&N filters. The noise only occurs at a certain point along the travel of the pedal, but now with the HIF carb its just the point for cruising at 60mph, which is really annoying.

Any ideas what i can do about it?

[Peetee]

I had a K&N cone filter with a HIF38 on my previous car. It had a hissing sound like you describe and it was just the induction sound heard through the filter (it was still there without the filter, only louder). It dissapeared above certain revs because of the greater noise background from the rest of the engine and exhaust and a growl coming through the intake. I think the hissing was just the sound of the air and fuel spray and the restrictive butterfly. Overall I wasn't happy with the noise levels so, with a tiny bit of filing I managed to stick the standard 1098 filter and casing on the end of the 90° alloy carb trumpet from a early 1300 engine. The standard filter didn't noticably reduce the power output but the end result was just as quiet as a standard engine.

[Cam]

Agreed. I too have a K&N cone filter and get the symptoms you describe. It's all part of having a tuned car! (unless you are clever like Pete )

[Willie]

Memories... I had a 1275 Midget with twin Webers, went like a
bat out of hell but I just couldn't stand the hissing induction noise
and quickly reverted to twin SU's with more efficient air filters.
Less performance but much more quiet.

[Kevin]

Memories... I had a 1275 Midget with twin Webers, went like a
bat out of hell

I bet Willie and I recon the fuel consumption was interesting too