Solex Carburetor Reboring ?? (worth it?)

[ahonda55]

Hi, GREAT forum, first time to post a topic.
Sorry but i am a Peugeot driver not Opel.
TONS of information about carburetors here, thanks a lot.
I have a small question..
I have a 2 barrel Solex carburetor "32-35 TMIMA"
what if i got the second barrel venturi re-bored a bit more?
Will the flat face instead of the rounded face of the inner venturi neck damage the carbureor ??
I am talking about inserting a 1mm or 2mm bigger diameter drill bit into the venturi, just to add 2mm or so to it's diameter.
Is that a good plan?
I consider re-jetting too after reboring the venturi.
Any suggestions?


Many thanks

[hrcollinsjr]

Originally Posted by ahonda55 I have a 2 barrel Solex carburetor "32-35 TMIMA" what if i got the second barrel venturi re-bored a bit more? Will the flat face instead of the rounded face of the inner venturi neck damage the carburetor ?? I am talking about inserting a 1mm or 2mm bigger diameter drill bit into the venturi, just to add 2mm or so to it's diameter. Is that a good plan? Many thanks

I'm sure others who have done this procedure will answer your question with some authority. I've never bored one out. I do have a question for you though. Usually when I see someone interested in doing this, it is for racing where they are required to run a certain carburetor. Are there no readily available larger carbs that will fit with little or no modifications available for you application? Most of us run Weber DGV series carbs either of the 32/36 or 38/38 variety instead of Solexes.

I know of at least one person on this list who has modified a 32/36 Weber by removing the choke and air horn on the secondary side of his carb. He also bored it out and ground a radius in the inlet to smooth the airflow into the secondary. Maybe he will see you post and answer your question and attach a link to the carb modifications I was referring to.

Good luck,

Harold

[baz]

do the chokes come out on this carb ? if so can you swop them or do they have sizes cast in which you dont want lol in say a racing class where carb mods are a no no

[opelnut10]

Originally Posted by hrcollinsjr I'm sure others who have done this procedure will answer your question with some authority. I've never bored one out. I do have a question for you though. Usually when I see someone interested in doing this, it is for racing where they are required to run a certain carburetor. Are there no readily available larger carbs that will fit with little or no modifications available for you application? Most of us run Weber DGV series carbs either of the 32/36 or 38/38 variety instead of Solexes. I know of at least one person on this list who has modified a 32/36 Weber by removing the choke and air horn on the secondary side of his carb. He also bored it out and ground a radius in the inlet to smooth the airflow into the secondary. Maybe he will see you post and answer your question and attach a link to the carb modifications I was referring to. Good luck, Harold

As stated, unless you are re-doing the Solex for some type of racing class requirements, it is far easier and less labor intensive to switch to a Weber. I did two Solexes which fell into the "stock appearing" class for racing class requirements. The first, and most important to me, modification is to start with a progressive linkage GT carburetor as opposed to the vacuum secondary. I then removed the secondary venturi and put it on the primary side (not a big deal) then bored the secondary side out 1 and 1/2 mm and blended the bottom to make a smooth transition to the throttle plate. Do not attempt to make this change if the carburetor will be checked with a bore gauge because it will get a failing grade but it made about a 80 cfm more flow change in the carburetor.

[Opelkurt]

Originally Posted by opelnut10 I then removed the secondary venturi and put it on the primary side (not a big deal)

I've thought about trying the same thing. What did you put in place of the secondary venturi (if anything) on the secondary side?

Originally Posted by opelnut10 it made about a 80 cfm more flow change in the carburetor.

Did you run stock jetting with your free-flow Solex? How did the car run after your mods?

-Kurt

[opelnut10]

Originally Posted by Opelkurt I've thought about trying the same thing. What did you put in place of the secondary venturi (if anything) on the secondary side? Did you run stock jetting with your free-flow Solex? How did the car run after your mods? -Kurt

The venturi are removable, there are two set screws that hold them in on the outside of the carb. body they are "staked" best I can remember and must be re-stake after modifications. I did not run anything in the secondary side and after boring filled the set screw hole with devcon and filed it smooth. As far as jetting you will have to play with that(as well as the idle air metering) It is just run it and read the plugs until you get it where you want it. The best method I found for Drag racing was to click it off at full throttle on the top end and coast to the return road and pull plugs and read them.

[ahonda55]

Heaps of thanks for every single person
I am not going to join any race, but the obsession to improve the performance and no problem with any tests
By the way, i have a Peugeot 504 2.0 1979.
My car
The venturi is cast and not removable, so all i can do is just grind some of it to widen it a bit more.
Watch the photo..


After reboring, even a very small amount of drilling, this will produce a flat egde, will this form a big problem?

Opelnut, please if you have any photos for the "operation" post them or send them to me.

Many thanks again

[wrench459]

I started out using a power hone to bore out the secondary but gave up because of the stones clogging every two minutes. Then I tried an one inch very course drum roll mounted on a die grinder. Worked out nicely then finished out with the hone. After that came hours of blending all done by hand.
Have Fun with the solex
http://www.opelgt.com/forums/opel-en...t-32-36-a.html

[ahonda55]

Originally Posted by wrench459 I started out using a power hone to bore out the secondary but gave up because of the stones clogging every two minutes. Then I tried an one inch very course drum roll mounted on a die grinder. Worked out nicely then finished out with the hone. After that came hours of blending all done by hand. Have Fun with the solex http://www.opelgt.com/forums/opel-en...t-32-36-a.html

Very nice, the photo here
http://www.opelgt.com/forums/943-post5.html
is exactly what i was afraid of, so everything went ok with you i see.

...so i should give it a try

[baz]

you sure they are cast in ? just had a peep at some on the pug site and they look like removable chokes from what i can see

looks like remove the accelerator pump jet thingy ( tech term for the brass jets on top with 2 legs )

remove venturi

then looks like the chokes would come out the top , there will be some sort of locking stud but they do look like they should come out to me


another thought

carbed bmw 2.8 to 3.3 ( pre series cars ) used solex didta carbs , same patten for the bolts iirc and come in bigger choke sizes

[ahonda55]

Here are some photos for what i have (taken by a member "Damien" in aussiefrogs.com)

It is not removable !

[baz]

yep looked @ them and some on a french site and there there was this photo



in it the chokes look to be removable when the top plate is off
could be a different carb i have never played with solex apart from as door stops as they have never stayed on any car of mine longer than a trip out to get a weber after first getting a car

as i said

just looks that way to me from the photos i found

[ahonda55]

Yes in this carb it is clear, but in my Solex, the venturi is cast, like a Weber 32-36 DGAV it is cast too !!
I will start re-boring the carburetor very soon. And i will post the results here.

Greetings

[P.J. Romano]

Ahonda 55,
Those chokes are removable. You may increase diameter of the venturi tube but it is questionable if you will improve the performance. You might well find out that the performance might deteriorate. The principe of venturi tube is to create lower pressure that will suck the gasoline through the calibrated jet. Venturi Tube Simulation. If you change the shape of venturi tube (make the flat face, as you say), you will decrease the under pressure and you will likely get lean mixture which will deteriorate the engine performance.
I strongly suggest that you find discarded carburetor, remove the venturi tubes and carefully increase diameter using lathe, not the drill. That way you will increase diameter but keep the shape of venturi tube. Play with those modified tubes until you find which diameter works for you.
You might find that increased diameter will not do any good, in that case, you can still return your original venturi tubes.
I played with carburetors in my young days and learned this the hard way.

[ahonda55]

Originally Posted by P.J. Romano Ahonda 55, Those chokes are removable. You may increase diameter of the venturi tube but it is questionable if you will improve the performance. You might well find out that the performance might deteriorate. The principe of venturi tube is to create lower pressure that will suck the gasoline through the calibrated jet. Venturi Tube Simulation. If you change the shape of venturi tube (make the flat face, as you say), you will decrease the under pressure and you will likely get lean mixture which will deteriorate the engine performance. I strongly suggest that you find discarded carburetor, remove the venturi tubes and carefully increase diameter using lathe, not the drill. That way you will increase diameter but keep the shape of venturi tube. Play with those modified tubes until you find which diameter works for you. You might find that increased diameter will not do any good, in that case, you can still return your original venturi tubes. I played with carburetors in my young days and learned this the hard way.

Romano you make me wish to have Opel, to join this forum years ago, so many thanks.
So the main thing is the rounded edge, but if i got rid of the flat problem i may get some improvement, just like another carb with a wider venturi.
The venturi is removable?? strange, they look cast and there is no place to insert a hair between the tube and the carburetor body !!, the auxiliary venturi is removable yes but not the choke itself, i will inspect again.
Anyway, after all these talks, i rather not to perform anything. Because i dont have another carb !
At least i may use a sand paper to "eat" some of the venturi side walls to keep the rounded edge.
Many thanks for you all, but the topic will still open for any information.

Greetings

[wrench459]

Oh my bad I didnt post my progress with the carb.
one angle http://i250.photobucket.com/albums/g.../carbmods1.jpg
another http://i250.photobucket.com/albums/g...e/carbmods.jpg

With a 2.0L I'm hitting 115 gm/sec @ 3750 rpm's.

http://i250.photobucket.com/albums/g...wnthetubes.jpg

[ahonda55]

Originally Posted by wrench459 With a 2.0L I'm hitting 115 gm/sec @ 3750 rpm's. http://i250.photobucket.com/albums/g...wnthetubes.jpg

Many thanks for the photos, looks great!
Sorry i didn't get what you mean by the 115 gm/sec, emissions?, please explain more about performance and fuel consumption changes on the same motor.

Greetings

[wrench459]

Originally Posted by ahonda55 Many thanks for the photos, looks great! Sorry i didn't get what you mean by the 115 gm/sec, emissions?, please explain more about performance and fuel consumption changes on the same motor. Greetings

It gets tough when changing intakes,carbs,valve lash... to know if I'm going in the right direction. So I've started measuring air flow with a maf sensor.
I picked this one http://i250.photobucket.com/albums/g...000fordMAF.jpg up at the locale salvage yard for 20 bucks.
Fuel consumption is terrible when the secondary opens due to the six step increase in main jet size. It also moved the torque curve but it sure is fun to drive
The carb in action http://s250.photobucket.com/albums/g...ent=32-3Xa.flv

[ahonda55]

Very nice work, you have removed the air horn perfectly too.
Many thanks for your efforts

Greetings