2 replies to this topic

[Skortchio]

Or more accurately, what's the sprung thing attached to the butterfly, my other HIF44 seems not to have one and it looks like it's solely designed to get in the way of the air and fuel

 

[lrostoke]

Its called a poppet valve, think its something do with emmisions

 

found this

 

HIF Improvements

 

One area where the HIF changed from the HS was the fitment of a wax-stat that was meant to make minor adjustments to the jet so that as the air got warmer, thinner and less dense it would compensate.  The wax-stats can give problems later on, especially if the car is stood idling in traffic for long periods, resulting in rough running.

 

Another change was the fitment of "poppet valves" on the butterfly spindles.  This was designed to reduce the amount of fuel settling on the walls of the inlet manifold when the throttles were snapped closed as you took your foot off the pedal.  As the throttles opened again, the unburnt fuel would result in poor emissions.  To counter this the poppet valves would briefly open as the throttles closed allowing a small amount of air through to prevent fuel condensing.

 

However, over time, the valves become worn, and can affect the setting up of the carbs, making it difficult to get a decent idle speed.  In addition, the valves were quite sizeable and thus caused a major restriction in the air flow through the carb.

 

Therefore when rebuilding the HIF carbs use throttle plates form the HS carbs.  This immediately reduces the restriction, and makes setting the carbs a lot easier as I found.  More importantly, the immediate and noticeable benefit I found was that I had much better engine braking when coming off the throttle.  If you are not rebuilding your carbs, then it is usually recommended that you solder the valve closed.

Edited by lrostoke, 26 May 2013 - 06:37 PM.

[Skortchio]

Cheers buddy!

 

That was basically what was going to happen to mine, just wanted to make sure it wasn't something really rare and interesting before it landed in the bin!