Restriction in return line

[zzzzed]

When running triples with mechanical pump, do I need the restriction in the return line for fuel pressure. Would this make my car run lean?

[Scoota G]

When running triples with mechanical pump, do I need the restriction in the return line for fuel pressure. Would this make my car run lean?

Yes have restriction Mick. It will run lean otherwise and backfire at the carbs.

[zzzzed]

That might explain why the first carb revs highest. It's the first one in line to get the fuel.

 

[Roberto]

If there is no restriction, block off the return completely.  See if that helps things.

[zzzzed]

I have a set of British su's on there at the moment and they are running sweet. I will see if I get time to give the triples one more go during the week.

[Scoota G]

I will see if I get time to give the triples one more go during the week.

There is an art to tuning them, just listen to it. If it pops through the carbs, too lean. If it pops at the exhaust on idle, too rich.

[zzzzed]

There is an art to tuning them, just listen to it. If it pops through the carbs, too lean. If it pops at the exhaust on idle, too rich.

 

Oh no  it's popping at both ends. 

[Enzo]

Hi, by British SU I presume that you mean 2". Can yo tell me what needles you are using.

David

[zzzzed]

Hi, by British SU I presume that you mean 2". Can yo tell me what needles you are using.

David

 

Hey mate I have only had the su's 1 week.

I bought them thinking they were hitachis

I will pull the needles tomorrow to see if they have numbers on them.

The l28 is stock as far as I know, with the su carbs it pulls hard all the way through the rev range.

I am very happy with them.

[Scoota G]

Popping at rev range? Idle? 2500RPM? Please explain or video?

[zzzzed]

Popping at rev range? Idle? 2500RPM? Please explain or video?

 

It revs up fine with no popping. It only pops at idol, if you could call it idol.

[Scoota G]

It revs up fine with no popping. It only pops at idol, if you could call it idol.

Popping at carbs or exhaust?

[zzzzed]

Both

[zzzzed]

The restricter did not fix the problem. It just mate the revs more stable.

It is still popping from both ends. Something is not right as the middle carb idle speed screw is all the way in and not touching the throttle arm. That's with the linkage arms disconnected

Oh we'll back to the su's for now until I have time for a closer look

[Zedman240®]

You may have an air leak somewhere...grab some aerostart or similar and spray it around the carby and where it joins at the manifold and between the inlet manifold and head... if you hear the revs change, that's where your air leak is.

[zzzzed]

You may have an air leak somewhere...grab some aerostart or similar and spray it around the carby and where it joins at the manifold and between the inlet manifold and head... if you hear the revs change, that's where your air leak is.

 

I have tryed 3 different manifold gaskets as well as 3 different sets of cab to manifold gaskets. I have had the manifold faced. I have been trying to chase air leaks since I first fit them. No mater what I do the problem doesn't change. Even now I have them on a totally different engine. I am almost ready to bin them.

[Zedman240®]

Bushings that support the butterfly shaft do get sloppy when they wear and leak from there. Spray around the carby itself as it may be leaking from there.

[zzzzed]

I will take them off for now because I have run out of time and money. I will order a rebuild kit from wolf creek when I have time.