Varijet 2 carb tune up

[Opeloutbacks]

Hi folks,

Just got the Manta road Worthy. Anyone know of a Crypton type tuning shop in the east midlands area. Got some flat spots for sure.

[BarryD89]

Guess it depends where you are, but I’ve used CoolClassicsMK in Wolverton (near Milton Keynes) for service and bodywork and I’ve zero complaints.  Most old school garages still seem to have a mechanic who understands carbs and can tune without a computer 🤓

[Irmscher Man]

I have a guy near to Rugby that is an ex VX/Opel service engineer and understands the Varijet like the back of his hand. He has got mine running nicely with a few simple tweaks. If you can find an old school garage, they should know what to do as the Varijet is not a complicated carb.

[Opeloutbacks]

I've found an old school garage with gas analyser, MOT station.  It's been tricky finding somewhere that will tune a carb locally. The two places that were recommended. One insisted that new Webber fitted before looking at it. The other that a lambda sensor would need installing!

Irmscher Man, Thanks, Rugby is doable. I may ask for his details, if I get no joy.

 

[Opeloutbacks]

Tuning was done today. Found a guy, who's mobile, with all the Crypton kit and gas analyser on his van. His name is Ray and here's a link to his website. 

https://trust-tune.com

Cars running sweet once warm. Very pleased.

May live with the rough cold running or maybe look into manual choke conversion assuming that would improve it? Doesn't take much cooling down to use the choke again which is irritating.

[TheRealExile]

18 minutes ago, Opeloutbacks said:

Tuning was done today. Found a guy, who's mobile, with all the Crypton kit and gas analyser on his van. His name is Ray and here's a link to his website. 

https://trust-tune.com

Cars running sweet once warm. Very pleased.

May live with the rough cold running or maybe look into manual choke conversion assuming that would improve it? Doesn't take much cooling down to use the choke again which is irritating.

Interesting, where in Derby is he? I have a non Opel project (another one!) with twin carbs that could do with a balance!

[cam.in.head]

if it brings on the choke too early after switching off then its not sorted yet .and not all old school mechanics understand the carbs settings (certainly a better chance of most current "fitters " thou !.

the choke has its basic settings on a pointer on the side and strangely it gives different positions for basically the same carb when on a 2.0 cih vs a 1.8 ohc ?

idealy you want around 7-8 mins from cold start to fully open and the marks rely on a brand new unit .ours will have weakened on the bimetal spring over time so its a case of trial and error rather than stock settings.  coming back on too soon suggests that it needs backing off a little providing the cold start time doesnt get too little.

the choke also has a vacuum pull off pod which was always prone to splitting its diagragm ! this causes over rich cold starts for a minute or two !

they are not the simplest of carbs and have various drillings and passages that can become blocked over time and affect the running settings. mine has a varijet on it that i bought brand new around 20000 ml ago and is still a fussy bugger especially with modern fuel even thou i only use 99ron esso.  and various road tests back in the day still had some cars with running issues / flat spots when new !  so getting them to run perfect now can be a nightmare.

yes people fit webbers but thats not whats supposed to be there and once sorted a varijet performs well enough .

[Opeloutbacks]

12 hours ago, TheRealExile said:

Interesting, where in Derby is he? I have a non Opel project (another one!) with twin carbs that could do with a balance!

He's mobile

9 hours ago, cam.in.head said:

if it brings on the choke too early after switching off then its not sorted yet .and not all old school mechanics understand the carbs settings (certainly a better chance of most current "fitters " thou !.

the choke has its basic settings on a pointer on the side and strangely it gives different positions for basically the same carb when on a 2.0 cih vs a 1.8 ohc ?

idealy you want around 7-8 mins from cold start to fully open and the marks rely on a brand new unit .ours will have weakened on the bimetal spring over time so its a case of trial and error rather than stock settings.  coming back on too soon suggests that it needs backing off a little providing the cold start time doesnt get too little.

the choke also has a vacuum pull off pod which was always prone to splitting its diagragm ! this causes over rich cold starts for a minute or two !

they are not the simplest of carbs and have various drillings and passages that can become blocked over time and affect the running settings. mine has a varijet on it that i bought brand new around 20000 ml ago and is still a fussy bugger especially with modern fuel even thou i only use 99ron esso.  and various road tests back in the day still had some cars with running issues / flat spots when new !  so getting them to run perfect now can be a nightmare.

yes people fit webbers but thats not whats supposed to be there and once sorted a varijet performs well enough .

Thanks Cam in head, this is helpful and gives me the next steps to try. I want to persist with the carb as is, as the originality is important to me and the car I believe (last owner).

I didn't expect Ray to work on the choke, he knew it was a bi metal strip, we discussed tweaking it, but that I would take a look when car was cold again. 

I'm going to digest what you've written, and ascertain my next step and may have some more questions.

Thanks again 

[Jessopia74]

The Webber was an option on auto cars iirc

[cam.in.head]

if you are happy to do basic checks yourself this may help you 

on cold engine

remove air  filter . open and close throttle .   choke should spring shut and throttle idle screw should land on top ridge of stepped lever.  apply vacuum to the vacuum pod (or manually pull the linkage of the vacuum pod towards you )the choke flap should open slightly and if you blip the throttle the  idle screw should drop to the next lower step . sounds a bit complicated but will make sense when you see it .theres a good chance that the vacuum pod won't hold vacuum. they have a diaphragm inside that can split. new ones are harder to find nowadays ?. then you could turn on the ignition and see how long it takes for the choke flap to open . should be around 7-8 minutes .any more than 10 is too much but it's adjustable by loosening the 3 screws and turning it . 

obviosly make sure all the linkages are nice and free and not hanging loose ! and the vacuum pipe ( and carb vacuum )are all plugged in correctly 

to be honest the haynes book does show and explain it pretty well ( i think the carlton book gives a little more detail too ! )

[Jessopia74]

The issue with Varajet is that is was crap implementation of a good idea and had always been crap from day 1. This is why most do want to swap them out as that was the go to solution to any complaints about them. Even the Solex was a better carb for the Manta.

However I do keep one on my 1800 and pretty much battle with it constantly. It’s either great at running when warm, or great at cold start then a bit crud when warm.  It’s been well documented over the years about the flat spots and I guess with the modern fuels, the slow response of the opening would be no longer even in acceptable range that does highlight the weaknesses of this carb. Shame really, but unless you have someone that has spent a lot of time with a Varajet and modding them it’s never going to be good all rounder. 

[cam.in.head]

yes i must admit they are a strange hybrid design using a normal choke mechanism and venturi on the primary but with a variable needle stromberg style on the secondary . also the part load  needle  for primary mixture !

as we know they had issues on brand new cars in the day with flat spots so they must have been a bit fussy back then. can't comment on the weber option on autos as i've not seen one personally over the years but that doesn't mean they weren't an option somewhere .varijets are the only type listed in my cav book with a diff part number for autos ??

as i said ,mine has a varijet  on it . bought new 20k ago in the late 90's and it still isn't perfect. cold starts are spot on, choke time is good and the car pulls great whilst warming up . THEN once warm you get a bit of surging when maintaining a steady 30 or 40.improved by adding ignition advance and by gapping plugs to 32thou. a slight improvement also with the vac advance dissconected !    would never consider a weber but did think about trying a 1.6 soles 32/32 jetted as required . 

last resort would be going jetronic as it's already got an injection tank on it and i have all the parts req but nice to keep it as orig for now .

[Opeloutbacks]

On 25/05/2024 at 13:49, cam.in.head said:

if you are happy to do basic checks yourself this may help you 

on cold engine

remove air  filter . open and close throttle .   choke should spring shut and throttle idle screw should land on top ridge of stepped lever.  apply vacuum to the vacuum pod (or manually pull the linkage of the vacuum pod towards you )the choke flap should open slightly and if you blip the throttle the  idle screw should drop to the next lower step . sounds a bit complicated but will make sense when you see it .theres a good chance that the vacuum pod won't hold vacuum. they have a diaphragm inside that can split. new ones are harder to find nowadays ?. then you could turn on the ignition and see how long it takes for the choke flap to open . should be around 7-8 minutes .any more than 10 is too much but it's adjustable by loosening the 3 screws and turning it . 

obviosly make sure all the linkages are nice and free and not hanging loose ! and the vacuum pipe ( and carb vacuum )are all plugged in correctly 

to be honest the haynes book does show and explain it pretty well ( i think the carlton book gives a little more detail too ! )

Cam in head, if I've understood correctly, the process is testing the choke setup and vacuum pod without running the engine?  

I adjusted the choke towards 'richer' and as expected the choke ran longer, making the running more stable. It ran at 2000rpm for about 5 minutes then about 1500rpm for about 2.  What speed would you expect the engine to run at during this time. Running a cold engine straight from starting at 2000rpm, seems a bit harsh.

[1900SR]

On 25/05/2024 at 17:33, cam.in.head said:

   would never consider a weber but did think about trying a 1.6 soles 32/32 jetted as required . 

 

My A runs a Solex 32DIDTA as standard, and if I wasn't so keen on it being original I would have fitted a Weber years ago.

[cam.in.head]

you will notice that the carb mechanism has a lever with a screw on the end of it that rests on different steps of another lever . to the side below the choke unit. ( makes sense when you see it !)  the end screw is for setting the fast idle .  2000 is way too fast. mine runs around 1200 and drops to around 1000 on first blip . you arnt altering any actual carb or mixture settings by playing with this screw so nothing to worry about . the haynes does give a setting but set it to what seems best for uou .

On 27/05/2024 at 20:13, 1900SR said:

My A runs a Solex 32DIDTA as standard, and if I wasn't so keen on it being original I would have fitted a Weber years ago.

 

On 27/05/2024 at 20:13, 1900SR said:

My A runs a Solex 32DIDTA as standard, and if I wasn't so keen on it being original I would have fitted a Weber years ago.

is yours a 1.6 ?  i must admit that all my previous 1.6 cars with the solex had no issues . this is why i mag consider it on a 2 litre

[1900SR]

1 hour ago, cam.in.head said:

is yours a 1.6 ?  i must admit that all my previous 1.6 cars with the solex had no issues . this is why i mag consider it on a 2 litre

No, it's a 1900, the A series had the Solex on both 1600 and 1900. I honestly think if you're thinking of changing then the Weber is the way to go, I had one on my other Manta 1900 a few years ago and it ran better than the Solex equipped one.

 

[cam.in.head]

ah i thought the 1.9 had the big zenith as on later b's. 

the idea of trying the solex is an experiment realy just to see if the surging i get is down to the carb. its on a std spec 2 litre with the only mod being the correct electronic distributor from a carlton .with the varijet being known as a fussy carb even back in the day and the solex relativealy trouble free ( in my personal experience) its worth a try. obviously i would need to make an adaptor plate or fit a 1.6 inlet manifold as the footprints are different.  jetting would have to be experimented with no doubt but i would be happier with a solex knowing that it was an oem fitment ( at least to a cav )

[Jessopia74]

Think I have a new Webber adapter plate, could draw up and have them laser cut quite cheap.  

[Kr1s]

12 hours ago, cam.in.head said:

the only mod being the correct electronic distributor from a carlton

This is very likely telling grandmother how to suck eggs, as you do say it's the correct distributor but it's a risk I'm going to take just in case it's helpful:

I remember from when I did my 2.2 Carlton engine upgrade on my GTE that the Manta 2.0 distributor has a mechanical advance mechanism, whereas on the 2.2 Carlton it was mechanically fixed and the advance taken care of by the electronics.

Has the distributor you're using definitely got mechanical advance?

[Trooker]

15 hours ago, cam.in.head said:

ah i thought the 1.9 had the big zenith as on later b's. 

the idea of trying the solex is an experiment realy just to see if the surging i get is down to the carb. its on a std spec 2 litre with the only mod being the correct electronic distributor from a carlton .with the varijet being known as a fussy carb even back in the day and the solex relativealy trouble free ( in my personal experience) its worth a try. obviously i would need to make an adaptor plate or fit a 1.6 inlet manifold as the footprints are different.  jetting would have to be experimented with no doubt but i would be happier with a solex knowing that it was an oem fitment ( at least to a cav )

Back in the mid 80’s the camshaft in my Dad’s ‘77 1.9GL Cavalier wore out a lobe, as the car was over 120k and he had the chance of a low mileage smashed Rekord 2.0S we put the 2.0 in the Cav. He eventually swapped the Zenith with its flat spot for the Solex off the 1.9 and it ran fine. 

[cam.in.head]

11 hours ago, Kr1s said:

This is very likely telling grandmother how to suck eggs, as you do say it's the correct distributor but it's a risk I'm going to take just in case it's helpful:

I remember from when I did my 2.2 Carlton engine upgrade on my GTE that the Manta 2.0 distributor has a mechanical advance mechanism, whereas on the 2.2 Carlton it was mechanically fixed and the advance taken care of by the electronics.

Has the distributor you're using definitely got mechanical advance?

hi. yes always worth asking . mine is the correct distributor. from a carlton mk2 82/83 2 litre with carb. this was used as it will have all the correct advance curves required ( even thou a 2 litre injection one would probably work ok !)and as you say the 2.2 has electronic speed advance system (no centrifugal)

8 hours ago, Trooker said:

Back in the mid 80’s the camshaft in my Dad’s ‘77 1.9GL Cavalier wore out a lobe, as the car was over 120k and he had the chance of a low mileage smashed Rekord 2.0S we put the 2.0 in the Cav. He eventually swapped the Zenith with its flat spot for the Solex off the 1.9 and it ran fine. 

this where it appears to get complicated. until recently i thought all 1.6s had the solex 32/32didta   all 1.9 had the zenith inat and all 2.0s had the varijet .    it seems early 1.6 and 1.9 ( a series ) both used a solex 33/32 although i would imagine the  jetting would be slightly different .

[Trooker]

12 hours ago, cam.in.head said:

this where it appears to get complicated. until recently i thought all 1.6s had the solex 32/32didta   all 1.9 had the zenith inat and all 2.0s had the varijet .    it seems early 1.6 and 1.9 ( a series ) both used a solex 33/32 although i would imagine the  jetting would be slightly different .

Apologies, messed up with the details. You’re right, the Opel 2.0 had the Varijet which was the reason I commented in the first place 🤯

I’m now wondering if it was actually a Zenith or Solex on the 1.9. Either way, the 1.9 carb was a success compared with the 2.0 one. It was over 40 years ago 🫣👨‍🦳

[cam.in.head]

yeah our memories are not what they were . not that mine has ever been much use anyway !

[Opeloutbacks]

Hi, latest update.

I've made good progress with carb autochoke set up. Choke operating well 1200 rpm from startup. Rises a little a minute or two later, this is due to the mid step cam being uneven, may file it even. Then drops to a 1000

Things to notice. When adjusting from lean to rich, very noticeable difference. Black soot out exhaust when rich and struggling to rev when lean, was straight forward to set where it needed to be.

Choke overide vacuum pull off. Tested manually by removing pipe and hearing satisfying air suction and placing finger over input hole, this stops it move and does create some force. Managed to find a nos replacement, for stock just incase.

Thanks for the help and encouragement, including the for and against. I've grown a little fond of the carb, we've bonded a little through our getting familiar 😁.

I do want to maintain the cars originality.

 

 

[cam.in.head]

yes the choke mechanism is relatively simple once you get your head around its operation and i doubt very much that any modern mechanic would understand it ! in a garage .

the varijet when working is fine. the only gripe i have with mine is that its a little hesitant and surgy ! when trying to maintain a smooth and constant speed . thats why i thought about trying a carb from a 1.6. but   like you  i prefer originality and the varijet will stay if it can be made to run better.