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Question about tuning strommy on 202

Started by _Chriskoss-79uc_ , Aug 12 2008 09:48 PM

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#1 _Chriskoss-79uc_

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Posted 12 August 2008 - 09:48 PM

Greetings,
On Holdenpedia I found an article how to tune the strommy on a stock 202.

It has an idle screw as well as a fuel/oil mixture screw, as seen in this picture : http://gallery.oldho...00275b.jpg.html

But, I can only find 1 screw which I believe is the right screw (fuel/oil mixture)... I cannot find the other regular idle screw.

Im looking on the right side and everything . Can anybody help me out? Do some strommies only have 1 tuning point?
Its the stock carby on my 202.

Thanks

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#2 LX2DR

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Posted 12 August 2008 - 10:14 PM

Small one on the base is the mixture screw. (Fuel/Air, not fuel/oil, thats for 2 strokes!)
Idle screw is the spindle in the solenoid, 3rd point is for the choke.

Edited by LX2DR, 12 August 2008 - 10:16 PM.

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#3 TerrA LX

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Posted 12 August 2008 - 10:33 PM

You have a later model UC which will have a slightly different carb, as above, Air/Fuel mixture screw will be located in the base plate and the Idle Speed adjustment screw is somewhere connected to the same throttle linkage as the throttle cable.

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#4 _gtrtorana_

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Posted 12 August 2008 - 10:48 PM

This carby will have a fixed size main jet. Fuel mixture (not idle mixture) can not be adjusted unless if this jet is changed or drilled out. I have seen some old school cars with adjustable type jets fitted but these are not factory fitted. I used to have a size 65 main jet when I used to run the single barrel stromberg.

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#5 rodomo

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Posted 13 August 2008 - 12:59 AM

Step 0:
Is this your carby? :huh:

Step 1:
Warm up engine.
Step 2:
Stop engine, disconnect wire at blue arrow.
Step 3:
Start engine and adjust base idle at yellow arrow to 450 - 500rpm. (Use a tacho)
Step 4:
Adjust idle mixture (orange arrow, your screw might be recessed?) to achieve maximum idle rpm. Turn this screw 1/4 of a turn at a time and wait for engine to stabilize.
Once you have achieved the maximum idle rpm, turn the screw in until the tacho drops 50rpm, this will put the adjustment "in the ball park" for emissions.
Step 5:
Re-adjust the base idle at the yellow arrow to 450 - 500rpm.
Step 6:
Stop the engine, re-connect the wire at blue arrow, restart the engine and give the accelerator a little kick.
Adjust the little bolt in the end of the solenoid (green arrow) to achieve an idle speed of around 650rpm. (Maybe a bit higher if auto, put it in drive and see what it idles like?)

Posted Image

This is the way I do it, works for me, may not be right in others brayns, no co-respondance will be entered into. :tease:

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#6 FastEHHolden

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Posted 13 August 2008 - 10:52 AM

yeah..sounds like your a bit confused...it has an Idle mixture screw and idle speed screw....its has a fixed main jet so that cant be adjusted..unless its modded.

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#7 _The Stig_

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Posted 13 August 2008 - 06:06 PM

Your idle mixture screw also controls the mixture just off idle as well. Sometimes if you get the idle mixture too far out you can have a little "Stumble" just as the throttle valve passes over what's called the transitional port.

http://images.carcra...ure_circuit.jpg

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#8 _Chriskoss-79uc_

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Posted 13 August 2008 - 07:14 PM

Your idle mixture screw also controls the mixture just off idle as well. Sometimes if you get the idle mixture too far out you can have a little "Stumble" just as the throttle valve passes over what's called the transitional port.

http://images.carcra...ure_circuit.jpg

Yeah this is what is happening.It kicks back 100rpm every now and then, and im not getting as muh power as I used to,.

Doing what Rodmo said would fix this>?

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#9 TerrA LX

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Posted 13 August 2008 - 08:20 PM

Clearing the blockage ive been onto you for the last month may fix it lol

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#10 _The Stig_

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Posted 14 August 2008 - 05:39 PM

Don't be afraid to take the mixture screw out completely and spray some carby cleaner in the idle passage - the plastic tube that comes with the can is ideal for this.

I'll tell you about an old bush mechanic's trick (I'll probably get flamed for this, but I have tried it and it does work. Plus I don't really care!) - sometimes (Usually) if you have dirt in your idle circuit you can get rid of it by "Backfiring" the engine. What you do is swap a couple of plug leads over, put your foot flat to the floor, start the engine and wait till it backfires 3 or 4 times, then switch it off. Put the plug leads back in the correct places and start it up and see if it has improved at all. Now I know some people are horrified by this, and will tell you all sorts of disasterous things that can happen as a result. Some of them are possibly feasible, but I've done it numerous times, without causing any problems at all. I wouldn't hesitate to do it with an old strommie, I'd just take the air cleaner off and have someone standing by with an old blanket that they can throw over the carb if it catches fire.

The theory is that the backfire blows the dirt or whatever back out of wherever it has lodged itsself, most likely ending up back in the float bowl. Considering you can easily drain the float bowl on a strommie it's probably not a bad option. Just do it at your own risk :<_<:

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#11 rodomo

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Posted 14 August 2008 - 05:48 PM

I've heard of that but personally I prefer a hand job.
This way the muck gets sucked through.

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#12 _Chriskoss-79uc_

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Posted 14 August 2008 - 05:52 PM

EDIT - dont worry I found them but they were bolts not screws lol.

Should I be playing with the solenoid screw and the bade idle screw, I have never touched them before though, so I was thinkin theres no need to play with them. Only screw thats been played with is the idle mixture.

Its been using alot of fuel does this mean its too far out as the stig suggested? Should I screw it all the way in and start screwing it out from there and see what happens?

Edited by Chriskoss-79uc, 14 August 2008 - 06:02 PM.

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#13 TerrA LX

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Posted 14 August 2008 - 06:13 PM

Dont touch the solenoid, and carb was tuned fine last time i checked it from the time before that, only way the tune would go out is if someone has moved the screws.

When are u free?

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#14 _evil UC hatch_

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Posted 14 August 2008 - 06:40 PM

Its been using alot of fuel does this mean its too far out as the stig suggested? Should I screw it all the way in and start screwing it out from there and see what happens?

thats only idle mixture, it wont make much difference how much fuel you use because when your driving the fuel travels through a different passage which has the main jet inside the carb to regulate how much fuel you use, if you are using heaps more fuel than you should than I would think that you actually have a problem with the carburettor

Edited by evil UC hatch, 14 August 2008 - 06:43 PM.

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#15 _Chriskoss-79uc_

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Posted 14 August 2008 - 07:17 PM

Mmm, I was scared of that. So the idle mixture only restricts or increases the rpm.. nothing to do with fuel flow?

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#16 TerrA LX

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Posted 14 August 2008 - 07:19 PM

no, the mixture screw governs the amount of fuel mixed with air at and just off idle.

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#17 TerrA LX

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Posted 14 August 2008 - 07:21 PM

maybe there is something wrong with the EGR valve since you have disconnected the standard air filter and fitted that stupid sports filter?

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#18 _The Stig_

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Posted 14 August 2008 - 07:23 PM

thats only idle mixture, it wont make much difference how much fuel you use because when your driving the fuel travels through a different passage which has the main jet inside the carb to regulate how much fuel you use, if you are using heaps more fuel than you should than I would think that you actually have a problem with the carburettor

Hmmm, starting to sound a bit like maybe a powervalve stuck open, if it's all of a sudden using more fuel than before and not running right. Maybe worth a look at that, that will give you a rough idle too (Too rich mixture). The powervalve in a strommy from memory is held open by a spring plunger that's located in the airhorn (Top) of the carb, and as soon as it gets a vac signal the plunger pulls upwards and compresses the spring, closing off the powervalve. When the throttle is opened vac drops off and spring pushes the valve open, bypassing the main jet. Bear in mind I haven't touched a carb in 20 years - and have a terrible memory!

I have to also point out that diagnosing fuel problems over the internet is a bit of a challenge to say the least - but I don't mind racking my brains every now and then, to keep my "Hand in it"....even if it is only a cyber hand lol

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#19 _The Stig_

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Posted 14 August 2008 - 07:27 PM

I've heard of that but personally I prefer a hand job.

Hmmmm I concur!

"This way the muck gets sucked through."

Ummm, yeah :spoton:

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#20 _Chriskoss-79uc_

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Posted 14 August 2008 - 07:30 PM

Oh ok.. I appreciate every1's help alot by the way. My car would be collecting dust still if it wasnt for you all

Well im in the market for a new carb then as I know these 1 barrell strommies are useless as shit anyway.

Is there any point changing over to a single barrel weber 34 inch. Found 1 on ebay, doesn't look anything like those 34adm's off falcons though?

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#21 TerrA LX

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Posted 14 August 2008 - 07:45 PM

No, direct replacement strommy will give less trouble

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#22 TerrA LX

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Posted 14 August 2008 - 07:46 PM

When ru free, would like to re tune it before you line someone elses pocket?

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#23 _The Stig_

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Posted 14 August 2008 - 08:02 PM

When ru free, would like to re tune it before you line someone elses pocket?

The old strommie was very under-rated in its day....and probably still is! They are actually a very good carby. You can still get pretty good HP out of them too, just ask the HQ racers...