Mixture settings on a varajet

[85berlina]

Hi guys,

I would just like some advice on setting the idle mixture setting on a varajet.
Before you ask, it is because the carb has been overhauled and the mixture setting is out of wack.
So, what is a good accurate way to do this and how do the pros usually do this.
Also, does any know how to adjust the adjustment screw that screws into the throttle body and keeps the main butterfly slightly open. I think it may called the idle stop screw and I can't find any information on adjusting this. This is out of whack because someone else has played.

Thanks

[Dayvo]

for the initial setting screw the mixture screw all the way in then wind it out 1 1/2 . Start you engine then wind it in till the revs just start to drop then turn it the other way till the revs start to change again ,half way inbetween these to points is about fight . This is a rough guide only .
Will have to check out the inle screw , been a few years since i have played with one

[Not_An_Abba_Fan]

The idle speed adjustment on a Varajet is the larger screw in the side of the carby on the front driver's side.

[85berlina]

Thanks Dayvo
I know that you can get the varajet carbs idling incredibly smooth. I know because mine used to be like that. The problem is, is that then I had a mechanic guy who doesn't know much about these carbs play around with it when he shouldn't have.

I shall explain:
My varajet has a mixture screw on the throttle body for the idle mixture.
It has an MIXTURE BYPASS screw for the idle speed located on the main body above the mixture screw.
It also has what Gregories call an IDLE STOP screw which is located on the throttle body at the back of the carb.
Please see pictures attached to understand what I mean.


The IDLE STOP screw cracks the accelerator butterfly open slightly and the adjustment will affect the idle mixture and idle speed. This is set by the factory and is not to be adjusted.
So if idle mixture needs to be adjusted only the idle mixture screw is adjusted and if idle speed needs to be adjusted then only the MIXTURE BYPASS screw is adjusted.
The problem is, is that people who don't know much about the carb adjust the IDLE STOP screw for the idle speed adjustment and once this is adjusted the engine will never run smooth. I can't find any information for resetting this adjustment because all the books say DON'T adjust it.

If adjusted correctly a varajet will run very smooth and when ever so slightly out, the varajet will run good, but not to its best.

So, is there any books or any other information on setting the adjustments such as the idle stop screw (A dedicated varajet book or something) and does anyone know of any places in Sydney that know heaps about tuning carbs, has the equipment to do it and does a good job.

[Dayvo]

Try checking out the local phone book for carby reconditioners , They should be able to help you out . or find some 50 + year old mechanic from the old school who would know them inside out. ha ha ha .I'll have a dig around and see what i can come up with.
Cheers Dayvo

[85berlina]

Got some more pictures to confuse everyone more.

This is of an old spare I have laying around.

The first picture is of the throttle body showing the IDLE STOP screw.

The second is a side view of the IDLE STOP screw.

The third is a view of the bottom of the IDLE STOP screw showing it pushing against the accelerator lever and keeping the butterfly open slightly. As you can see, this would affect idle mixture and idle speed.


Thanks for the help

[Goon]

Wish i knew the original setting myself bro, id change mine in a heartbeat

But what i do know is, it will changer cars idle in gears, so set it to what the revs should be at tthe gear.. and listen to the sounds of the revs from the engine and exhaust note while tuning.

Take her out of the highway look at the rpm at 100k and see if it needs adjusting.

Ill research around and let ya know if i can find it.

[jpetrou]

In the past I have mucked about with varajet carbies on various different 6cylinder models from 173 to 202 engines on VC/VH/VK models. They all have small quirky variances between each other, but basically the idle screws are the same. I have never adjusted the basic idle screw (thats the one that holds the thottle slightly open). It is set by the factory for emissions. Varajet carbies are designed to idle lean mixtures (for emissions), so they have set this screw in a position to allow more air to flow at idle to retain low fuel to air ratio. I have attached a couple of pages of minor adjustments on varajet carby for VK. This is from the geniune Holden VK Service manual P/N M39101.

[Not_An_Abba_Fan]

I found this, don't know how useful it would be. http://oldholden.com/possible/index....et_Carburettor

[Goon]

Ive found that one before abba, thought i was in the right spot, though it says allot more on how the carby operates with certain parts and cars etc..

From what i can try and read on thos vk pages jpertrou, i might be wrong cant read it that well but it doesnt look like it has the info either..

I had another search and cant find it, thats why ive gone by what i said above.

But somebody must know!!!

[jpetrou]

Sorry guys, I didnt realise I had compressed the pages so much. So here goes again.

[Goon]

Thats ws good mate, thanks it taught me about the fast idle screw which i don't use anymore due to no more choke

The screw where chasing settings for is the stop idle screw.

fast screw and the 2 mixture screws we already know..

But while where chatting about carby settings, just for a future thought.. anybody knopw the stting for the vaccum screw? the screw that sits on the plunger near the choke. i havent touched it, i just got a 2nd carby im cleaning up and the screw is all the way in

[85berlina]

Thanks heaps for all your help guys,

I actually talked to a carby guy that recos varajets and he told me a method to tune the thing.
To do it properly you need a vacum gauge. I have already tried most of the method and it is heaps better than before. All I need is to get the vacum gauge and fine tune it and hopefully it should be all good. I will let you guys know.

About the vacum screw, i have that information in my GMH manual. It is for a VK and I don't know if it would be different for a VC but I can post it for you if you want.

Thanks again

[Goon]

Yeah that would be good mate if u could...

About the vaccum gauge, i have one so what vaccum should it be sitting on to be right? below or above 40?

[14secvp]

do a google search "vacuam gauge tuning" the first page that comes up is very informative would post a thread but I here you get in trouble for that now.

[Goon]

Thats good stuff bro, but im talking about the screw here for the car not the gauge and how to read it etc i already know this..

[14secvp]

www.centuryperformance.com/vacuum.asp go here if you havent mate just what you want to know your search might have been different than mine this is how to tune with a vacuam guage

[Goon]

Yeah i read that page mate, i wanna know what it should be sitting at, i can change it up or down and she will stil be normal, you know..

Thanks anyway mate, good find others will like this..

ps. i would rather screw setting details bt that seems impossbily to find as it also controls the revs..

[14secvp]

yeah my ute has one of these carbs on it took ages to get it tuned right just had to fiddle with it for days till I got it right but yeah this screew can be a pain if its been moved a long way I no longer have the bigger screew open at all and nothing connected to it I just use the butterfly screew and the little mixture one now.It has no emmission gear left either.If you set it so its cracked open enough to get a sewing needle between the butterfly and the carb should be a good start not enough and it will cough as you rev off idle.Just probably have to play around a bit.someone must know the proper method though.

[14secvp]

probbably get in trouble for this but heres exactly what you want mate, oldholden.com/possible/index.php/Varajet_Carburettor
or http://www.bevenyoung.com.au/bookworks.pdf

[Goon]

Thanks again mate, but ive read that to.. i think its also posted on the 1st page of this thread

I might hunt down a GM VC service manual soon, i almost had one on ebay but lost all is needed factory setting details

[SoulGrind]

I wouldn't mind finding something on the varajets stop screws.
I have a VH manual that basically says leave em alone. Nothing about how to adjust them to get them back to their original setting.

[Goon]

Yeah sucks, my book says the samething same as everything else, but what if it has been touched !!! im hoping this service book im chasing might just have those details

[14secvp]

one of those threads said to increase performance and economy put the two barrel weber of an xe falcon six on there these must be cheap be the only bit of a ford not rusted out yet.

[yobbo88]

I got this info from my tafe teacher and its from an article from the "VACC" not too sure but it seems ok "Although no official ex-factory adjustment exists, the following method has been devised after a considerable amount of trial and error. If the idle needle screw has been tampered with and is preventing the engine from idling correctly it is possible to restore the base idle by turning the additional mixture screw in all the way until it seats. Having done this, adjust the throttle stop screw until the engine is idling at between 450 and 500 rpm.
Using the additional mixture adjusting screw, slowly increase the engine idle speed to approx. 800 rpm, making sure not to touch the throttle stop screw. Finally, raise the idle to approx. 900 rpm, using the idle mixture screw.

That doesnt give you the exact spec of the stop screw in numbers but if you do it then work out where the stop screw ends up then you'll know maybe?