Tuning Varajet carb

[Joes_meat]

I just got my VC finally running with an engine transplant.

It's running a bit rough though.
Doesn't cold start very well (fine with ether) and stalls if I don't hold the revs. So I think I need to raise the fast idle? I would raise the fast idle until it cold starts well and idles well when cold?

Then do the same with the slow idle screw?

I'm also wondering what the mixture bypass screw does? Air/fuel mixture? If so, great because she's running a bit rich. How would I set this properly? Would I need an O2 sensor? If so where would I put it on the exhaust?

 

[craigvk]

On the side of the carb there is a screw with a point on it and then there is a butterfly type latch that has several sections on it. When cold, it should be closed so the choke should be closed and you adjust that screw to the startup idle speed. The more clockwise you turn it the higher the idle will be. I think I set my brothers to about 1/4 inch on the point side. So when you start the car when pushing the pedal a bit to start it, the car should fast idle by itself while it warms.

 

[brettyb2002]

hey i usually do mine by ear.. adjust ur idle so its idles reasonably smooth let it warm up a bit first though.. when u have set your idle...get someone to give it some revs why u put ur hand at the back near the exhaust and why whoever revs ur car , check to see if u get liquid on ur hand why u hold it close to the exhaust , close enuff without burning urself then if u do , adjust ur mixture until u get the most minimum liquid on ur hand , then take it for a drive and make sure it doesnt coff and splutter , thats basically how i do my varijet , they aren't really the best carbies to work with but yea i have the same problem u do ..anyway hope this gets u somewhere or helps u in somew ay

cheers
bretto

 

[Joes_meat]

I've got it idling and starting okay when warm.

Hwever, I don't think the choke is working. It's okay if I turn the latch manually, but it doesn't seem to come on by itself. Even with a full depress of the accelerator pedal.

Could this be due to my faulty temp sensor? It says the car is running off the scale hot even when cranking when cold.

 

[craigvk]

That would be something to look at.

Next time the car is cold, pop the bonnet and where you see the throttle with the screw on it, press it open throttle and the latch should drop meaning the choke valve should be closed. If it does nothing then it's something to look at. You might need to pull the carb off and rebuild it or maybe get another one. I think they are cheap to get second hand.

 

[Joes_meat]

That would be something to look at.

Next time the car is cold, pop the bonnet and where you see the throttle with the screw on it, press it open throttle and the latch should drop meaning the choke valve should be closed. If it does nothing then it's something to look at. You might need to pull the carb off and rebuild it or maybe get another one. I think they are cheap to get second hand.

I've got the old one from my old engine. I rebuilt it myself, but I don't know how good of a job I did - it'll probably leak all over the place.

I've also got a varajet II from a Camira - I assume they're the same carb.

 

[Goon]

Same setup joe and carby, if your cars an automatic before start i push on the pedal once then let it start it should go into auto choke, sometimes it doesnt work the first time.

The idle should drop after 1min, if you have a manifold gauge this will be a bonus after the 1min push the pedal again and try and keep the revs around the 40 mark on the manifold gauge, after awhile you should be able to let go of the pedal..

If she cuts out, DONT push the pedal this time and just start her with the key, she should resume normal rev's . "it may drop or climb but after time itll halt at a certain point"

with an rpm gauge the rev your after is 850rpm under 1rpm.

I've timed and tuned mine with extractors installed.