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HIF Carbureter

RonR

Jedi Trainee
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Hi Folks.

A friend is running a 1275 engine, with the original donor car being unknown. The engine was rebuilt very recently by someone "back east." Currently, there is a brand new SU HIF carburetor on the engine. It does not seem to run very well even after setting the fuel/air mixture using an exhaust gas analyzer.

The plug gap is set, the timing is set, and the points are set. We did not check the valve lifer clearances, rather assumed that the engine rebuilder did that properly.

Initially, from spark plug readings, it was running way too rich and would only run for a few minutes. After resetting the carb to the initial "2-turns back’ from the jet being level with the bridge, it started and eventually ran for an extend period of time. However, only after the engine was warmed up would it idle under 1000 rpm. This was on a day where the ambient temperature was in the 90s. As I was tweaking the fuel/air mixture (using the exhaust gas analyzer as a guide) all of a sudden the mixture went super rich without anyone doing a thing to the car. We shut the engine off and considered what might have caused the jump in fuel. For whatever reason, we checked the compression and found it was between 150 and 155 psi on all 4 cylinders, so no problem there. So we tried to restart the car, and it would not start. So here I am, seeking the wisdom of the British Car Forum members.

Another friend, who restored British cars for over 40 yeas, said that some HIF carbs have a flapper thing on the butterfly that he would always solder shut to get the engine to run right. He also said he preferred the original twin SU carbs over a single carb.

Any thoughts and suggestions would be appreciated.
Ron
 

Jerry

Darth Vader
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I think you need Doug! He knows minis very well. I can tell you that mine will not idle below 1000 but that is because of the cam I have in the engine. The timing is critical in this little engine. You are going to have to check that and it varies depending on the cam. More information on the rebuild would really help.
 

dklawson

Yoda
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Thank you for the flattering compliments. However, you give me too much credit.

Ron, I had already replied to your post in the Spridget section before I saw this post. I neglected to mention that Gundy in the Spridget forum has run Spridgets with HIF carbs. If he doesn't see and respond to your post, consider sending him a PM.
 

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