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Mon Jul 07, 2025 6:48 pm

ETA: New question posted below.

I have no idea what brand carb this is, the seller was unsure as well. I know he said it was a knock off, but I have nothing to go on to find out how to adjust it. I know there is one mixture screw which I have messed with but I cannot figure out how to increase the idle speed.

Has anyone seen one like this before?

Mon Jul 07, 2025 8:14 pm

Idle speed on the earlier Solex carbs (and presumably your similar knockoff) is adjusted by using the screw at the top of the throttle lever (the thing that moves back and forth when you step on the accelerator pedal), which regulates how far open the throttle butterfly is at the idle (no accelerator pedal depression).

Mon Jul 07, 2025 8:26 pm

kreemoweet wrote: Idle speed on the earlier Solex carbs (and presumably your similar knockoff)....

Which early solex would this be closest to? Maybe I can gain some knowledge by looking at those. 30 pict 1?

Mon Jul 07, 2025 8:39 pm

Looks like a 30 pict 1

Tue Jul 08, 2025 3:50 am

Yes that looks just like a 30 pict-1. Very easy carb to work on and I have used it on many engines in the last 45 years. I have never had one of these copies of those carbs so I cannot speak to the quality of it. The adjustment on the original is simple. Start the engine. Adjust the screw on the throttle lever to an idle speed you like, then slowly turn the mixture screw in till the engine stumbles, then back out slowly till it runs its best, then about 1/4 to 1/2 more turn and that's it. All of this is done with the choke flap wide open and engine at operating temperature. Bob

Tue Jul 08, 2025 6:56 am

Looks like the speed screw is already turned all the way in.
Find the procedure for adjusting the carb. the folks above think it is.
Start over. Maybe make sure it is clean. Check your timing too.
Unless there is something wrong with it. (is that why the seller was selling it?)
Good luck

Tue Jul 08, 2025 4:52 pm

Willin wrote: Looks like the speed screw is already turned all the way in.

It is. It's one of the things that has been bothering me since it was previously pointed out.

Today I backed it all the way out, adjusted the choke properly, and then adjusted the screw. It was EXTREMELY hard to start and idled so low that I had to stay on the accelerator to keep it running. It also backfired once or twice on my way to work.

When I got to work, I made a few more adjustments but the ONLY way to keep it idling properly is to keep that screw ALL the way in. There's no other way around it. I also screwed the mixture screw in until the engine started galloping a little, and then backed it out a half to full turn.

I'll be looking for a genuine Solex to rebuild and replace it with.

Wed Jul 09, 2025 3:35 am

I think your carb might be one of the Chinese copies that I see on eBay. I have not read any reviews on these. I have read reviews on the Chinese copies of the popular webers and of gm quadrajets. Some very well versed people with carburetors have found many incorrect things inside and the fixes were quite involved and not practical for the average person. I think in the case of this carb you will probably be better off getting an original solex and rebuilding. The difficult area of these is the throttle shaft bushing. If it is worn it will need to be rebushed. When worn this causes a vacuum leak which causes the mixture screw to not function. Good luck-Bob

Fri Jul 11, 2025 8:22 pm

So i was just about to pull the trigger on an H30/31 PICT that I would rebuild.

However I was reading Rob & Daves page and even though they say th 25.5mm venturi works well for 1500 and 1600 engines, they state that it's hard to tune.

Quote: One thing though - the H30/31 carburettor is usually delivered with very lean jetting, and if you are using it on a 1300 or 1500 it may be OK, but if you have a 1600cc engine in your '67, then it will almost certainly run lean, and be difficult to tune.

So now I'm not sure if I should stick with finding a 30 PICT, or if I should go ahead for the H30/31.

Fri Jul 11, 2025 9:02 pm

When I was bringing my 1966 single cab back from a 26 year slumber I decided to go through my small collection of German Solex carbs and have one professionally rebuilt by Tim at VolkzBitz.

I sent my best 30 PICT-1 and paid the man. Ended up with a perfect running 1600 single port. The engine actually already had a low miles Brazilian H30/31 on it I could have easily put a kit in but I wanted the perfect matching carb done up by probably the most reputable builder.

Money well-spent.

Fri Jul 11, 2025 9:21 pm

b-man wrote:
I sent my best 30 PICT-1 and paid the man. Ended up with a perfect running 1600 single port. The engine actually already had a low miles Brazilian H30/31 on it I could have easily put a kit in but I wanted the perfect matching carb done up by probably the most reputable builder.

Money well-spent.

So what I'm hearing is that a 30 PICT 1 and an H30/31 really don't produce much difference? I mean there's only a 1.5mm difference in the venturi and it's not like I'm going for racing performance or anything.

Sat Jul 12, 2025 9:50 am

Chris I think if you read through all the old carburetor threads on here which deal with these two carbs you will find that most prefer the original solex 30 pict-1. I have always used this carb on 1300s thru 1600s both single and dual port and on buses, Ghias, and bugs. For bigger than 1300 you want the 30 pict-1 with the 105-1 on the base because it has an enrichment valve for the larger displacement engines. Alot of people have run the 30 31 with good results. I think if you were going to spend the money to have one done by the person mentioned earlier in this post you would probably want the 30 pict-1. You could experiment with a used 30 pict 1 and rebuild it yourself. It's not real difficult and the thing to watch for is excessive play in the throttle shaft. If it is loose it will cause a bad vacuum leak. That would need to be rebushed by a machine shop or carb rebuilder. Good luck-Bob