Fuel jets

[ScottKinnear]

Hi lads, I had an afr fitted and have been messing around with jets.

Both primary and secondary ran 145

This give me 10 on my afr when driving lightly around 2000rpm.
When I throttled it it would rise to around 12.3 on full boost and stay around there all the way. Full boost is 18psi

I have since bought a few fuel jets to better my fuel consumption and heavy fuel ratio on normal drive.

I finally got round to putting in the 120 in the primary and it runs around 14 on a steady drive of 2000-3000 rpm.( which is optimum ) When I floor it it runs leans to around 16 before the second choke opens in which it now runs early 13.

If I ran the 125 jet it drove around 12.3 at 2000 revs but never leaned out like the last one. With highs of around 14-14.5 as I pressed the pedal and when the second jet opened it ran around 12.5

So should I stick with the 120 as I'm sure the leaning out before the second choke is opened cant be good or is this just expected?

[Markey Mark (BD)]

Do you run one of those twin choke carbs that TTS use to sell years ago? Think I remember saying you did at a Surrey meet a while ago

If so I don't think they have a boost enrichment circuit so getting the fueling right on boost might get alittle tricky

How many jets do those carbs use?

[ScottKinnear]

It runs two jets total. And yes a twin choke. I remember logg saying something about boost enrichment at the last Surrey meet .

Edit: I also edited my jet sizes as I wrote them in wrong
Edit 2: hopefully also now makes a lot more sense:)

[Markey Mark (BD)]

Is there any way of getting the second choke to open abit earlier?

The 120 main sounds about right for off boost driving but when it comes on boost it needs that extra bit to add the extra fuel

Maybe keep the second jet fairly large to aid the fueling, just need to bring it in abit earlier

[ScottKinnear]

http://i1355.photobucket.com/albums/q713/code50/null_zpsb310e8f1.png

http://i1355.photobucket.com/albums/q713/code50/null_zpsadb17a5a.png

A few pics and info.

[ScottKinnear]

I don't think so. The linkage is all pretty tight.

I assume the standard card would only reduce its afr as the boost was applied.?
I'm thinking the car will be less damaged with the rich fuel mix rather than lean mix.

What would be a safe afr max as I boosted before the second jet opened?

The problem isn't when you drag it as the foot is through the floor before it realises but when your driving and maybe sitting at higher revs the afr is just to weak. I'm only now realising the limitations to the carb.

Oh and heavey fuel bills!! :(

[fishead]

[quote=ScottKinnear;339909]It runs two jets total. And yes a twin choke. I remember logg saying something about boost enrichment at the last Surrey meet .

off the top of my head theres 10

[m1n1 (Jasper)]

If you need it, the whole pdf of the weber DMTR is on my sort of website.
http://members.home.nl/jaspervanhoek/
It's the top left link...

[ScottKinnear]

Thanks for the link jasper :)

Ten jets?? Does this many help me out anymore?