Jetting on standard DATR/DAT type Carb

[Ferrit]

Did  that and its soo much better now.     Thank you for this post and help

New plugs coming today and I will check timing again.

[Ferrit]

Capriblu  OMG what a difference!

https://youtube.com/shorts/dfvTMwgMbIA?si=IC9VXpw3XlDOrWcJ

Even no choke semi cold silly low tickover if just ran.  I owe you a coffee.

It will be interesting what the dyno people do with it now

[SanRemo78]

I think the dyne people will but the air filter lid on and send you on your way. That sounds really sweet!

[Ferrit]

 

That is music to my ears Guy, because it = cheaper. :-)

They said that if everything else is good (after a check) they would run a full power test.  Maybe I should 'open a book' and take bets on my cars max power output?  Anything North of 100 will be a start ;-)

[Ferrit]

Latest jetting from Harding dyno work

[lancialulu]

If you are running the latest, I would check the plug colour after a 50 mile motorway drive, as it could be too lean??

[Ferrit]

Based on?  This was after a few runs on a dyno and monitored AFR.  I will of course being checking plugs

[lancialulu]

Always worried when main jet is lower than OEM. You need to run rich at high rpm as fuel cools the engine just saying...

Tim

[A Ross]

Wow Mark - she's positively purring in that Youtube clip! I am preparing to have the same done to my Berlina which is running far too rich.

[Ferrit]

This was on the one but last runs with the their recommended jetting

[HFStuart]

AFR of 12 or below from 4k rpm? I'm not expert but that looks low. When I had mine set up on a rolling road they targeted 13 or a little above at full throttle.

[Ferrit]

I will take it on a run and see what the plugs look like.  Something I am wondering, the fuel inlet leak also equals air, could this be messing this up?  I will try to research, but thanks for the comments

[Ferrit]

So reminding myself what rich and lean are in the numbers.  Mike from Harding Auto's said he wanted to be on the rich side of safe.  Not that I have a clue.

https://youtu.be/3sh19RSa8vE?si=GqiHz7vTaJdPuwP5

10 being rich limit and 17 being lean limit.

I want a AFR gauge now :-)

[peteracs]

I will take it on a run and see what the plugs look like.  Something I am wondering, the fuel inlet leak also equals air, could this be messing this up?  I will try to research, but thanks for the comments

Hi Mark

The fuel level with the float dictates the carb fuel supply, so a weeping inlet should have not bearing on it especially given that there is positive pressure of fuel, ie fuel will come out and I would think no air gets in.

Peter

[WestonE]

Hi Mark 2 things to add to the pile. Betas pre IE VX ran the fuel pipe over the exhaust pipe and did not use an insulator block between the carb and manifold. This leads to hot running/ hot starting issues particularly with modern fuels that evaporate far more easily. It is easy and sensible to put some heat shielding on the pipe crossing the exhaust just behind the subframe. You can get the insulator blocks on the the internet, but do check bonnet clearance.

I have tried tuning by plug colour AKA plug cut tuning with twin DCOE conversions and it is hopeless compared to a Dyno session. I also ran AFR gauges at various times and can view one on the Monte if I wish. More comfort blanket than useful. My Monte ECU does tune from AFR actively at lower load/ RPM as most modern cars do as well. Log files can show me AFR tracks over time. But I do not have the skill or the dyno to re-map.     

You can test for air leaks with the engine running by spraying WD40 at manifold joins. A change of engine note will tell you where the leak is. You might need the rolling road to have another look, but sort out the hot fuel thing before going back.   

[Ferrit]

I will check.  Thanks Eric.  I have no starting issues or obvious hot fuel running problems but will bear in mind. 

Hopefully sorted the cam oil leak and can start driving it.  Thank you all

[Ferrit]

Back to this.  Low down its not right.  I yesterday went out for a longer run into the Surrey Hills.  Once moving its good, it low down it just doesnt feel easy to drive.  Not any other way I can explain this.  I drove it sprited but not much over 4k rpm.

All plugs look like this.  Too lean then?  So maybe I will go back to the jets Capriblu suggested and see what that looks like?

So you might ask 'why not take it back to the garage, well its a bit of a hike, and I just cant be arsed.  I could give you a list of issues I have with the place.  I am not sure I can afford to send it there again and be disappointed...

[WestonE]

Yes that looks lean. Not the chocolate brown you want to see.

[Ferrit]

thanks for replying Eric.  You all help me not feel helpless :-)