Carbtune results

[Eric Cunningham]

Gen 1 2006 - do the numbers look good for this attempt at tuning?
View attachment 20210807_162617.mp4

 

[RadiumPHX]

Looks pretty even, how does it look when holding a higher RPM? does the carbtune have dampeners?

 

[Eric Cunningham]

I recall that the mercury raises consistently while slowly increasing rpm.

 

[Parminio]

Odd. Your levels bounce all over the place to me. I'm not familiar with how that type of gauge operates, so maybe I'm way off base here, but my gauges (I use regular, analog vacuum gauges) don't do this:

Idle:




You hit the throttle:

 

[Screwloose]

Gen 1 2006 - do the numbers look good for this attempt at tuning?

I've got the same gauge and my readings are less bouncy than yours. On mine I could easily pull in LSF much tighter.

Have you got the dampers in each line, they come with the gauge and are there to reduce bounce? Also you need to do this job at tickover, as they run out when accelerating, its a happy medium at tickover you are looking for, no other rpm.

 

[Bullies74]

The levels look to be even.

I would suggest though, you check the inline dampers.

They are supposed be installed, in-line
closest to the vacuum ports.

 

[Parminio]

I've got the same gauge and my readings are less bouncy than yours.

I thought so.

Have you got the dampers in each line, they come with the gauge and are there to reduce bounce?

That would definitely explain it.

 

[Screwloose]

I thought so.

Yes it looks to be the dampers are missing, hope it's as simple as that for Eric!

I've used these gauges a couple of hundred times plus, and the VMax wants to sit at 20 on the gauge, the more even you get the metal rods inside the gauge, the more that reading pulls in for all 4 Off.

Anyway; hopefully a quick fix on that one.

 

[Eric Cunningham]

I've got the same gauge and my readings are less bouncy than yours. On mine I could easily pull in LSF much tighter.

Have you got the dampers in each line, they come with the gauge and are there to reduce bounce? Also you need to do this job at tickover, as they run out when accelerating, its a happy medium at tickover you are looking for, no other rpm.

I think I followed the instructions. Where the white tape is wrapped, I have the clear tubes inserted and they were attached on the carb side rather than the instrument side.

 

[Parminio]

That looks odd. Out of curiosity I went to the Carbtune website and their parts look different. That looks like you have tubes bigger than the black lines on there when in the online instructions it's clear tubes that are smaller than the black lines.

https://www.carbtune.com/delivery.html
Maybe they've upgraded and changed the system. I don't know.

 

[Screwloose]

I think I followed the instructions. Where the white tape is wrapped, I have the clear tubes inserted and they were attached on the carb side rather than the instrument side.

My readings are definitely allot less bouncy then yours.

Is there anything else lying around that you could use as additional dampers. I cannot remember the spec for these readings but I suspect you may be running out of spec. Another thing is that you need to keep the temp stable, I use 2 household fans on the engine to do that, a clean air filter, and have the A/F screws set at factory spec to give you a good starting point.

Have you checked your not drawing air somewhere above or below the carbs, a quick spray of oil would momentarily show that up.

Additionally; I done an overhaul of the carbs last year, electrics and valve clearances so maybe that has helped me on this subject.

 

[Eric Cunningham]

That looks odd. Out of curiosity I went to the Carbtune website and their parts look different. That looks like you have tubes bigger than the black lines on there when in the online instructions it's clear tubes that are smaller than the black lines.

https://www.carbtune.com/delivery.html
Maybe they've upgraded and changed the system. I don't know.

I see black plastic looking restrictors - the ones I received but don't use are brass.

 

[Screwloose]

I see black plastic looking restrictors - the ones I received but don't use are brass.

Parminio is correct, I've just had a look at mine and you can see the restrictor (attachments below), also look at the size of the very small hole that is the only air to pass through these restrictors.

 

[Eric Cunningham]

Yes, I did this.

 

[VMAXXIMUM]

Your set up looks good. Use the idle speed thumb screw and set your idle at 1800rpm. Then sync the carbs. Use very light pressure on the screws. It takes very little pressure to change the sync.

 

[Eric Cunningham]

Your set up looks good. Use the idle speed thumb screw and set your idle at 1800rpm. Then sync the carbs. Use very light pressure on the screws. It takes very little pressure to change the sync.

I will try that suggestion on rpm. I ran about 1k once warmed up. I learned early on about the pressure on screws lol.

 

[Parminio]

Well, that's the oddest thing I've seen in a while.

Put my gauges on it and it's perfect. They all stay nice and level up and down the RPM range. How Eric got it that perfect with it bouncing all over the place like that is beyond me.

 

[Mr. Max]

Eric, did you cut that clear tube to four pieces (four restrictors)? That should not be that bouncy, no way.

 

[Screwloose]

I will try that suggestion on rpm. I ran about 1k once warmed up. I learned early on about the pressure on screws lol.

Eric, here is a Youtube video of your Carbtune and VMax, this is typical of how much bounce you should have, and the leveling of the rods. Me personally do not accept anything less than that, and if I cannot get it, then I will have a problem somewhere like drawing air and such-like.

See 1 minute 17 secs.



Good luck man.

 

[Eric Cunningham]

Yes, I saw this and wondered why mine is doing this. I may contact the mgfr to see if they may have a solution.