9 replies to this topic

[Spud_133]

Hi all, as above what needles should I be running in my twin hif4s? My engine is a 1293 with 276 worked head lcb and rc40. I am trying to get to the bottom of why the it revs lovely until you let off and the revs stay at a fast idle and then slowy drop down to where they should be. It is not the throttle linkages, choke linkages or the cables as they all return to the stop.

[Spud_133]

Bump

[Spud_133]

Are needles the same design for hif4s and hs4s?

[AVV IT]

I'm confused, are we talking about HIF 44's, or HS4's here as I've never heard of a HIF4? 

Edited by AVV IT, 05 May 2013 - 03:46 PM.

[iwatkins]

Throttle butterfly's opening and closing smoothly? Could be worn spindle(s) causing it to catch and then close. Also assume the return springs are all there and providing enough return action?

Just guessing here mind.

Cheers

Ian

Edited by iwatkins, 05 May 2013 - 07:40 PM.

[Spud_133]

All of the linkages return as they should and are shutting off correctly. Just that they hold the revs high then slowly drop off as if its running out of fuel then idles happily

[Spitz]

I am running twin 1.5" carbs......relatively stock 1275 with lightened FW and KN filters.

 

#5 needles seems to work great

[Spud_133]

Hi all, I've been checking out some things today, and have a few things to report. The needles are AAUs, however when the engine is running, fuel is running out of the overflow and could fill a 500mm bottle in less than 5 minutes. It is not a sticky needle valve when you blow through the carb and lift it up, it would stop. also we measured the distance between the bottom of the float bowl and the needle valve.

Also when turning over the engine the right hand piston chatters, we have tried a second spring and ensured the dashpot is full of oil.

 

Any ideas please?

[Spud_133]

Standard 998 manual pump at what pressure that is?

Edited by Spud_133, 06 May 2013 - 09:02 PM.

[Spud_133]

I will have a look when I get to the car, it's 40 minutes away at the minute, and a bit late.