Got a new Brosol H30/31 on the 1600sp engine

Its running very well, but the idle adjustment is tricky because when i screw the small volume control screw in, it SPEEDS UP... the engine idles fastest when its screwed in all the way to the bottom - WTF?!

Sam

most carbs do get quicker when you screw them clockwise which is in

supposed to be the opposite - screw in and gets slower, eventually stalling it

?????

What happens when screwed all the way in?

Hi,
Tune these by referring to the 34 Pict 3 section of rob and Dave's site mentioned in the above post.

Also, did you clean & blow out the the carb before putting it on?

Enjoy
Ctefeh

[ Edited on 4/4/2007 by ctefeh ]

With the volume screw screwed all the way in (till it stops), the idle is fastest! Its supposed to be cutting off the fuel supply during idle, yes?

Bizarre - interested that you say the idle jet may be too large... how does that work? I have a smaller one which i could try (it currently runs rich at idle and the reason i have started tinkering is that its difficult to start, i.e. takes 8 or so seconds of cranking then coughs to life)

on a side note can i ask how much u paid for the new brosol?

100 and something US dollars, plus postage, minus 50 US dollar voucher from CiP after i complained when it leaked fuel everywhere

it runs v well!

thanks for that.

Do you have 2 adjustment screws ??? or only 1 screw one or both all the way in before you start the engine then back out 3 full turns this will give you a good starting point

adjust as necessary

If you have 2 screws are the O rings in good condition ???

Just making sure we are all talking the same adjusting screws as you did say "when i screw the small volume control screw in"
1) is air bypass- the larger
2) is mixture or volume control

[ Edited on 5-4-2007 by Bizarre ]

Hmmmm reading Rob and Daves link his Brosol adjusting appears to be talking about a Pict 30 single screw adjuster.

As Ctefeh said, it needs to be set up like the pict 34/3 2 screw

No, its like the picture... yes, it is the smaller screw that i'm talking about - its called the "vilume control screw" in most places look... the bigger is the "air bypass screw", yes?

anyway, had both out - new o-rings, blew out the holes... screw the small one all the way in and it speeds up. I started them both at 2.5 turns out

???

Samblers,
Is the idle cutoff working? Is the carby flooding (easier to tell after the engine is switched off)?

Also on a side note, what distributor are you running? The H30/31 isn't great at playing with certain types.

http://www.thesamba.com/vw/forum/viewtopic.php?t=185095 


Ctefeh

Ctefeh, how can I tell if the carb is flooding? Presumably take the top off (carefully) and measure the float bowl level?

The idle cut-off is working fine… doesn’t run-on, even though its rich

I’m running an aircooled.net modified SVDA to suit H30/31, so no probs there.

Bizarre – thats cool… just wanting to understand how idle jet too big causes this problem?

Will try a 50 when I get home

if the idle jet is too large then it is shovelling too much fuel into the engine therefore when i screw the volume screw in all the way it cuts off most of the flow and allows the engine to run leaner where it should be however because the jet is too large u dont get the adjustment you need to fine tune.

am i right?

barry's right ur idle jet is definatley too big
with out knowing what size is in it now i;d try a 50 or a 45 and go from there
the engine should start/idle/rev happilly at 1.5ish turns out
if not and it smells rich its too big

I just changed the idle jet down from a 55 to a 50 and still same problem - small volume control screw fails to stall car when screwed all the way in, still bit difficult to start (but still runs great!)

???

Do i need to go to a 45? What next?

I'd say your getting a fuel/air mix from somewhere else beside the idle circuit.

Is the throttle plate completely closed?

A lot of people make the mistake of adjusting the idle with the throttle plate (the small screw on the throttle arm).
Just something to check.

Agreed - it is something else.

that said IF you can easily get a 45 - try it.

i had a set of 36 IDFs and same thing. 50-55's would "sweet spot" closed.

45's was 2 turns out - but clogged once a fortnight.

I should have letf the 50's shut off to see how it went.
I was too lost in getting the 2 turns out

Float set right??

Yeah, probably right about it getting fuel from somewhere else other than the idle circuit... I had thought that but dont really know enough about how carbs work to know what to look for next!

The throttle stop screw is NOT touching the cam by the way - i havent been setting the idle using this The throttle plate is completely closed as far as i can tell (and i've pushed the accel cable 'in' to make sure)

Whats the best way to find out if the float is set right? I've had the top off the carb and the little valve is working

???

At least your eliminating things.

From memory the float on these carbs is set with a washer under the needle seat, not sure what the setting is but as a guide the top of the float should be level with the carb top. In this position the needle should be shut.
Another thing to check would be fuel pressure, I'm not sure how much pressure these carbs like, someone else might know.
The other thing you could do is check down the carb throat with the motor idling to see if any fuel is dripping from the pump squirter or aux venturi. But be carefull, I use a mirror so if it backfires I don't get toasted.

I tried the accelerator nozzle thing - its not dripping.

First thing i'm going to do is change the needle valve for a different one and stick another washer under there (why not eh!), though i've never understood why these things need adjusting (manuf. tolerances surely cant be THAT bad!).

I've no way to measure the fuel pressure so will save that until last. We'll get there, even if it kills me (which it probably will)