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Carb mixture adjustment
Posted: Fri Oct 05, 2012 8:53 pm
by BBF Roadster
I'm trying to set the metering nozzles.
Mine are all out of wack.
If they are turned all the way in to lean,
How many turns out toward rich should they be roughly.
I hope someone can help so I can finally get it running.
Thanks
Re: Carb mixture adjustment
Posted: Fri Oct 05, 2012 10:36 pm
by Lee2000
Are you saying it doesn't run at all right now no matter where you set the jets? Every engine will be different but you might try a base line setting of 1 1/2 to 2 turns out from full lean. Just make sure EVERYTHING else associated with the engine's tuning is set-up and adjusted properly before going hog-wild turning jet screws.
Re: Carb mixture adjustment
Posted: Sat Oct 06, 2012 7:27 am
by jrusso07
1.5 to 2.5 toward rich is a good start. I tend to go rich as you adjust this out as you set up the system.
You should review this
http://www.311s.org/su-setup/su-setup.html" onclick="window.open(this.href);return false;
Re: Carb mixture adjustment
Posted: Sun Oct 07, 2012 2:18 pm
by BBF Roadster
The engine runs, but has no throttle response, just drones with no power.
I replaced the head and had it rebuilt, so also need to check valve lash.
Thanks for the ball park setting.
Re: Carb mixture adjustment
Posted: Sun Oct 07, 2012 5:09 pm
by GeoffM
If you have a micrometer, adjust the nozzles to a depth of .092" to start.
You should read this excellent write-up:
http://www.311s.org/pmwiki-311/pmwiki.p ... sNewSuTech" onclick="window.open(this.href);return false;
Re: Carb mixture adjustment
Posted: Sun Oct 07, 2012 8:54 pm
by BBF Roadster
I set the metering nozzles to two turns.
After a hard start again, I noticed a bad spark plug sparking around the ceramic.
Bought a new plug and it idles smoothly now. Yeah
Now when trying to rev the engine, it backfires through the carbs.
Also the distributor is set to full advance, but seems like it needs more advance.
Im very happy that it is closer to driving.
Thanks for any help guys.
Re: Carb mixture adjustment
Posted: Mon Oct 08, 2012 10:02 am
by Gregs672000
Dizzy may be a tooth off. There is a small degree of additional adjustment available by loosening the 8mm bolt that locks down the metal pointer on the dizzy. What is the initial timing set at? What curve? Also, check your firing order 1,3,4,2 counter clockwise. If you are not able to set the timing to where it should be you will have to remove the dizzy and set it correctly... let us know and we will walk you through it.
R or U motor?
Re: Carb mixture adjustment
Posted: Fri Oct 12, 2012 8:12 pm
by BBF Roadster
Thanks to everyone.
I pulled the distributor and started over.
The oil drive was 180 off,then I cleaned and greased the distriburator so the vacuum advance would work.
Now it idles smooth and revs like a beast.
Now I will hook up the new clutch cylinders and get my first attempt to drive this car.
But I better not go far since I have no brakes yet. Lol
Re: Carb mixture adjustment
Posted: Fri Oct 12, 2012 9:56 pm
by jamesw
That's what the e-brake is for on these cars (in south TX where it's flat).
Just make sure the e-brake is CONNECTED first though
Good to hear you got her running smoothly.
James
Re: Carb mixture adjustment
Posted: Tue Nov 03, 2020 8:23 pm
by v8_ranch
I know this is an old thread, but just wanted to say thanks! It affirms everything I have sort of stumbled into today working on my 68, after getting confused by reading a lot of other information about what to expect from the SU carbs.
Re: Carb mixture adjustment
Posted: Tue Nov 03, 2020 8:28 pm
by Linda
I think the .092 nozzle depth mentioned is confused with the .092 nozzle opening size for the 1600, as stated in the Tech Wiki article.
http://www.311s.org/pmwiki-311/pmwiki.p ... sNewSuTech
Linda
You are reading, which is GOOD
Re: Carb mixture adjustment
Posted: Tue Nov 03, 2020 8:30 pm
by v8_ranch
Yeah, I saw that as well, but was mostly looking at the baseline settings for mixture adjustment. Still trying to find a depth for the 2000, but I guess it probably doesn't matter if you know the approximate number of turns...
Re: Carb mixture adjustment
Posted: Tue Nov 03, 2020 8:36 pm
by Linda
Problem for me with “approx number of turns†is it is too “approximate†and therefor hard to “match†the carbs as well. I always thought “2 turns†etc was easy to duplicate, but measuring showed something else.
I suppose you could do “ 2 turns out†or whatever, then pull the domes and try to match per a measurement, then reassemble and run. Keep doing that till correct. Tedious, but once set the carbs should be good. Matching is important per ZTherapy instructions so I figure it is worth pursuing, but others might not care...
Linda
Nozzle size for 2000 is.100 per TW
Re: Carb mixture adjustment
Posted: Tue Nov 03, 2020 9:55 pm
by v8_ranch
Linda wrote: ↑Tue Nov 03, 2020 8:36 pm
Problem for me with “approx number of turns†is it is too “approximate†and therefor hard to “match†the carbs as well. I always thought “2 turns†etc was easy to duplicate, but measuring showed something else.
I suppose you could do “ 2 turns out†or whatever, then pull the domes and try to match per a measurement, then reassemble and run. Keep doing that till correct. Tedious, but once set the carbs should be good. Matching is important per ZTherapy instructions so I figure it is worth pursuing, but others might not care...
Linda
Nozzle size for 2000 is.100 per TW
Good thinking...
Re: Carb mixture adjustment
Posted: Tue Nov 03, 2020 10:16 pm
by spl310
If you want absolute accuracy, get a Gunson Colortune.