Solex sidedrafts - High Idle!

[twenty6]

As in one thats blocked off by that hose and one that's not? Do they both need to be blocked? Putting my finger over the one that isn't doesnt seem to do anything.

Thanks for your help can't try for a day or so, so will let you know then.

Searched and found that procedure for mixture screws was to screw fully in, the out 3 turns and start, from that then screw out to find highest idle and then screw in til rpm started to drop.

I tried that but idle mixture screws didn't seem to do much well not while 1 was changed anyway. It was running very rich though so no more than 2 turns (4 half turns) from fully in you reckon?

[Rodger]

Hi twenty6.

If you purchased these used, and as you say, you are new to this, then you are in the right forum for help.

A couple of things need to be done before you can get these to work.

It appears from the photos you have a Weber balance assembly between the two carbs. The screw is for balancing the two carbs and not for setting the idle speed.

The Weber assembly maybe good to join the two carbs but will never allow any tuning as there is no set up for idle speed adjustment and they would have had some work done to the levers to fit the larger diameter throttle shafts of the Solex. The holes may be not a good fit allowing some slop.

As a result of the Weber parts the throttle plates are totally tuned off. No air will be flowing through the idle/Pilot circuit and this is why the mixture screws have no effect.

The engine is running on the starter circuits and the by-pass valves. Very rich and this is why it speeds up.

The starter (not a choke on this type of carburetor) levers are in the correct position for being "off". Check where the locator/guide knob on the lever shaft under the cover is located in respect to the starter disk slot. You may find that the disk was not placed correctly when the cover was first put on. This will bend the lever when the cover screws are tightend down and there may be marks on the disk to show where the guide was binding. If this is not the case then rotate the disk to use the other slot and line up again.

I have all the Type T throttle levers and Throttle Stop Brackets that can be made to suit the gap between the two carbs all I need is a measurement between the two shaft ends.

To do this but pull from the other side. (The balance screw is under the black boot and these are S5 Solexes)



If you do search for the OEM Solex Toyota parts make sure you get Type T.

Or look for the Mikuni PHH40 levers (N115.104) and Throttle Stop Brackets (N107.073) to do a balance bar set up like this, also known as Type R.



This is an easy task with the Redline Manifold and some other Redline bits.

It would also pay to get a pair of Softmounts. This will help keep the manifold heat out of the carb bodies and help seal the two parts without use of gaskets or silicone.

PM me

Regards

Rodger

[twenty6]

Hi twenty6.

If you purchased these used, and as you say, you are new to this, then you are in the right forum for help.

A couple of things need to be done before you can get these to work.

It appears from the photos you have a Weber balance assembly between the two carbs. The screw is for balancing the two carbs and not for setting the idle speed.

The Weber assembly maybe good to join the two carbs but will never allow any tuning as there is no set up for idle speed adjustment and they would have had some work done to the levers to fit the larger diameter throttle shafts of the Solex. The holes may be not a good fit allowing some slop.

As a result of the Weber parts the throttle plates are totally tuned off. No air will be flowing through the idle/Pilot circuit and this is why the mixture screws have no effect.

The engine is running on the starter circuits and the by-pass valves. Very rich and this is why it speeds up.

The starter (not a choke on this type of carburetor) levers are in the correct position for being "off". Check where the locator/guide knob on the lever shaft under the cover is located in respect to the starter disk slot. You may find that the disk was not placed correctly when the cover was first put on. This will bend the lever when the cover screws are tightend down and there may be marks on the disk to show where the guide was binding. If this is not the case then rotate the disk to use the other slot and line up again.

I have all the Type T throttle levers and Throttle Stop Brackets that can be made to suit the gap between the two carbs all I need is a measurement between the two shaft ends.

To do this but pull from the other side. (The balance screw is under the black boot and these are S5 Solexes)



If you do search for the OEM Solex Toyota parts make sure you get Type T.

Or look for the Mikuni PHH40 levers (N115.104) and Throttle Stop Brackets (N107.073) to do a balance bar set up like this, also known as Type R.



This is an easy task with the Redline Manifold and some other Redline bits.

It would also pay to get a pair of Softmounts. This will help keep the manifold heat out of the carb bodies and help seal the two parts without use of gaskets or silicone.

PM me

Regards

Rodger

Hi Rodger, Thankyou for your post!

My old set of solexs (which appear to look similar to the ones in your 2nd picture) ran these linkages, and I put them on these carbs because they did not come with any. If the 'throttle shafts' are the threaded bronze parts coming off either side of the carb which the linkges bolt on to, I can confirm they are a good tight fit.

Interesting what you say about no idle speed adjustment screw, so far I have just been changing it by screwing in/out the throttle stop screw.

When you say the starter plates are in the correct position to being off, are you referring to how they are in my pic? With the circle holes matching up with the circle holes underneath? that means the locator/guide knob is sitting in one of those circular holes. What I assumed was 'off' was lining up the locator/guide knob to those indentations.

The locator guide knob would sit where the top circle hole is in that pic.

I understand your a guru in this field but I can't understand why a linkage would be fine on another set of solexs but not these ones, don't know where to go from here..

Sorry for not PM'ing thought this post might help the thread

[Steve M]

I've got solexes that have the chokes coming on when they are pulled right, and others the come on when pulled left. The set up just depends on whether the carbes were set up to be mounted on the right or left side on the engine. From memory, the parts are interchangable.

If they hiss, then they're on, if they don't hiss, then they're off. I'm sure the other said this.

You do certainly appear to be missing the idle control feature on your linkages.

[Rodger]

twenty6.

The only screw I see showing in your pictures, connected to the throttle shafts is the balance screw. All it does when you turn it is open one carb relative to the other. The one to which the spring is attached will open some and hold the other carb closed. Turning it enough the other way will allow the other carb to float and close off the sprung one. Unless there is a means of controlling the two carbs idle speeds with seperate screws you will never get them to idle or balance up.

Are there any parts/levers on the other ends of the shafts, not visable in the pictures?

Are there more parts on the old Solexes?

My second picture shows the clockwise starter version used in LHD Toyota and good for RHD with carbs on passenger side. The disk has two holes and two slots, as you know. The post on the starter lever should locate in a slot. Have a play around with the orientation of each, allowing the lever spring to dictate the closed/off position. They should be on when pulled counterclockwise. If you cannot get them right, perhaps the disks have been swapped in another lifetime. Read off the stamped letter, if any, and I'll compare what I have here.

One thing to be sure of is you will know more about how these fangdangled Solexes work

Regards

Rodger

[twenty6]

Rodger,

The linkages (everything) I'm using are off the old working pair of Solex, what you can't see in the pic is where the throttle cable connects, there is a screw you screw in or out (bottom right screw of pic) that pushes the throttle lever down or releases it. Sorry about the pic if a better one is required I can take one this was just a pic of my old set.

[twenty6]

This is interesting,

Pulled the two choke/starters off and took the spring etc off the exterior, and turned the thread they were on 1 half turn around so the level was on the opposite site, this means that when the starters are pulled toward radiator chokes come on. Anyway, no biggie.

Turned the mixture screws in fully then out 1.5 turns each.

Turned the idle screw (on the throttle cable linkage) all the way out, car wouldn't start.

Turned the idle screw in 2 turns and the car started and idled just at 700rpm, after a few secs it did it's usual thing and climbed to 1000rpm then 1500rpm

Before starting I played around with the balance linkage, the carbs are no longer idling roughly and were pretty precise through the 700 up to 1500rpm range so I guess that's good.

Now, while it was idling high (but not as high cos idle is set so low) at 1500rpm I pulled one of the choke on the front car halfway toward the radiator and let it go and as it should the revs climbed as I pulled it and dropped back to when I released it but then the idle dropped back down to 700rpm after letting it go and went back to it's struggling idle.. ?

[Rodger]

Ok I see the whole picture now.

The set up as it is may work, however I'd strongly suggest that it will still not be easy to tune.

Vacuum, mixture, balance and linkage set up all contribute to how well or not the motor will idle.

Back to some basics with the way this is working. The long central return spring is acting on the rear carb lever and the throttle cable is connected to the very front end of the front carb with its return spring and speed screw?

Set up like this and without an idle speed screw to set the rear carb the two shafts and spring combination may interfere with each other allowing one carb or the other to open or close, differently each time the throttle is moved. Perhaps the long spring may not fully pull the rear carb against the front carb balance tab all the time.

It is not a good practice to drive that rear carb through the length of the front carb throttle shaft. The front shaft may not yet be twisted, it maybe twisted now, or it may twist if there is a slight bind in it causing erractic idle and progression behaviour.

All things working ok with the throttle linkage levers, a climbing idle speed can be attributed to a too lean Idle Mixture.

What is the value of the Pilot jet? If it is the typical Type T size it will be #63.8 or #65 both good for the 18R but if it is what was in the typical S5 (your old ones and #57.5) it will be too small by two sizes.

Try the bigger of the two jet sizes if not already in there. 1.5 turns of the mixture screws is around one jet size.

Sounds like you have worked out how the starter operates. I did not think you could have the lever installed in the other way, mainly because when I am putting them together I simply do it the way it was meant to be. Good find though. So the lever underneath now points to the jets?

Regards

Rodger

[twenty6]

Thanks for the reply Rodger, I will take a pic of the throttle cable linkage tomorrow to confirm for you.

About the internals - This is a guess at what the combinations of specific parts to sizes is so if they're wrong (ie called something the wrong thing) you could probably pick it up.

Main Jet: Old - 50 , New - 35
Idle Jet: Old - ??? , New - ???
Emulsion Tube: Old - 8 , New - 740
Air Correctors: Old - 57.5 , New - 52.5



Old was my old pair of s5 carbs and New are the ones i'm tryig to tune. Those Air correctors have the bottom hole machined, and the 2 bottom holes blocked up on the 'Old' set.

Bare in mind the Old set is the ones i'm running. If these sizes don't make sense I will take a pic of the bits and relate the sizes to each so you can tell if I've labelled something incorrectly.

[Rodger]

Twenty6,

Identifing notes have not transfered with this pic. So left to right Jets are as follows:

Main Air Jet (Air Corrector), Bleed Pipe, Jet Block, Main Jet (Fuel Jet) and below this is the Pilot Jet.



From what you discribe, regardless of what part you mention is what, any signs of drilling jet sizes or signs of soldered up holes on jets or bleed pipes will not be good. Someone sometime was playing a bit to try a few things.

The jets sized #50 and #35 are most likely the pump jets, not shown in the pic.

The ones sized #57.5 and #52.5 are the Pilot Jets and the ones we need to concentrate on. If they have not been drilled then here is the problem. They are both too lean for the motor.

Regards

Rodger

[twenty6]

Thanks Rodger

The Pilot jet sizes are

57.5 - in the carbs now
52.5 - came with the carbs

the 57.5's have both their bottom holes (2 out of 4) soldered up.

Do you recommend I run the 52.5 untouched ones?

The 'main jet' sizes of 35 and 50 are the jets put in just behind the idle mixture screw with screw top above them, which ones do you recommend?

As I said i've put all the internals from my old set into my new one, well most of what I could see, is it wise to if I change 1 then change everything so i'm reverting back to the setup which came with this new pair?

That 'Main jet(fuel jet)' I don't recall seeing one of those unless it was stuck to the bottom of the jet block then it would have been swapped over the same time.

[twenty6]

Sorry I should mention - The pilot jets which are soldered have 2/3 (since the only have 3 holes in the sides) soldered, and the bottom hole appears to be machined. And the car is running hi-temp plugs because on the old setup it would run worse and detonate after turn-off with normal plugs.

Changed the pilot jets to the 52.5's (non soldered) with the 'old' setup - car won't start

[Rodger]

twenty6.

Find or buy a 0.60mm drill bit (or a AWG numbered one close to that), probably from a hobby shop and drill out the #52.5 and try it. If the motor improves then you can decide if you want to buy new of that size.

The #57.5 is useless with solder in it. Someone was trying to change the way the jet emulsifies with the air by removing holes.

I still suggest the jet needs to be no smaller than #60. You are getting close to solving this.

Regards

Rodger

[twenty6]

Thanks will try that in a couple of days when I have a day off.

Is it all 3 holes plus the bottom (underneath) one or just the 3 holes on the side? And if pilot jet sizes are changed is it wise to change the bleed pipes, jet blocks etc don't know what combo to use out of the ones I have.. Guess I'll see how it runs.

[Rodger]

Just the hole at the bottom, which gives it the size, of the Pilot Jet. No other jetting needs to be changed at this point in time.

Once we have the motor running smoothly at idle and on the Pilot System (idle to 20% throttle) then we can sort through the main jetting.

Regards

Rodger