How are your SU carbs set up? Looking for a baseline for adjustments.

Tech tips and how to's

Moderators: notoptoy, S Allen, Solex68

User avatar
Linda
Fraternal Den Mother-RIP
Posts: 7807
Joined: Sat Nov 05, 2005 11:37 pm
Location: Los Angeles
Model: 1500/1600
Year: High Windshield-68-70

Re: How are your SU carbs set up? Looking for a baseline for adjustments.

Post by Linda »

If you don't have them, try the ADQ needles for a 1600. They help the idle.

Linda
Last edited by Linda on Tue Nov 03, 2020 2:53 pm, edited 1 time in total.
Sadly-Linda has passed away 2022. She was the 311's den mother and drove the first Rare-Parts ball joint project. RIP.
User avatar
svwilbur
Roadster Fanatic-Site Supporter
Posts: 688
Joined: Fri Aug 10, 2012 1:29 am
Location: Santa Cruz Mountains, California

Re: How are your SU carbs set up? Looking for a baseline for adjustments.

Post by svwilbur »

I have a 2000 with SU's.

I had issues for a long time with my rear carb, cylinders # 3 and #4 running too RICH and turning the spark plugs black.

For a little while it was partially the CHOKE cable to the rear carb was hung up on the holder. The cable running up out of the carb was lifted up and caused the CHOKE to be ON just a little bit. Basically that pulls the Nozzle down which richens everything.

When I figured that out it still ran rich and sometimes would run rough at idle and if you sat a long time (5-10 minutes or more) at Idle it would kind of get so rich that when i would accelerate from idle it would smoke some.

Then I found that the nozzle was riding loose on the little connecting bracket that pushes it down when you pull the choke. By loose I mean you could put your finger under the nozzle and push it up and it would go up a little. You could wiggle it up and down. When it was down it was running richer, up and it would run leaner. You need to have the nozzles be sitting up against the bottom of the carb without any looseness. Then tune them.

There was no good way to fix this other than slightly bending the choke bracket (connected to the bottom of the nozzle ) on the side out away from the carb and push it up a bit to take up the slack. Then check that the CHOKE still works ( nozzle goes down when it is pulled and goes back up and seats firmly against the bottom of the carb when the CHOKE lever is pushed back in OFF position at your dash). Make sure it is smooth and consistent in setting back in the full up position with no looseness. ***This fixed my richness problem***.

Basically that nozzle was bouncing around a bit so I would have it pushed up when I adjusted the carbs and balanced and adjusted them but then when I would use the car it would float down with use and gravity and then be too RICH. That made my plugs run BLACK.


*** So verify that there is no movement of the nozzles with the choke in the OFF position. If it is loose then it can bounce around and will give inconsistent results.


After than fix I was able to get it so that the spark plugs would all burn tan color after a few hundred miles. Just richen them if they burn white and lean them if they burn blacker. Once they are all tan in color you are close. You may also need to check air balance again after adjusting them for lean and richness.

While at Mount Shasta i also had Kieth Williams look at it for a rough idle issue and my air balances and rich/lean adjustments were pretty good. But he advised leaning about a quarter turn to try to see if we could get the idle to be a bit smoother. That did help and now it runs at idle a bit smoother than before. He said that if at highway speed if it skips every once in a while or hesitates a part of a second to richen it back up a bit. So far it has been good in the 1/4 leaner position.

I averaged 31 MPH on the trip.

I do need to lower the idle RPM speed a bit as I guess leaning it out that 1/4 turn raised the idle speed a bit.

Also make sure you do all this carb tuning when the engine has been fully warmed up. Otherwise you will end up tuning it cold and it will be too rich once it gets warmed up. To run these cars they have to be CHOKED to start if it has not started in a day or so and they have to have the throttle held down to keep them running or you need to pull that throttle cable out (on the far left of your dash) to keep it running until it has warmed a bit.

If you try to turn the carbs when they are cold it will be off when they warm up.

So check those choke cables and choke levers and nozzles.
Stacey Wilbur
1970 2000 SRL311-14335 White
User avatar
Linda
Fraternal Den Mother-RIP
Posts: 7807
Joined: Sat Nov 05, 2005 11:37 pm
Location: Los Angeles
Model: 1500/1600
Year: High Windshield-68-70

Re: How are your SU carbs set up? Looking for a baseline for adjustments.

Post by Linda »

Z Therapy can rebuild the nozzles back to spec. Don’t throw out your old nozzles.

Linda
Last edited by Linda on Tue Nov 03, 2020 2:33 pm, edited 1 time in total.
Sadly-Linda has passed away 2022. She was the 311's den mother and drove the first Rare-Parts ball joint project. RIP.
User avatar
v8_ranch
Roadster Fanatic
Posts: 109
Joined: Sat Oct 10, 2020 11:13 pm
Location: Jackson, TN
Model: 2000
Year: High Windshield-68-70

Re: How are your SU carbs set up? Looking for a baseline for adjustments.

Post by v8_ranch »

Does anyone have the baseline depth of the 2000 jets? Is it different than the one listed in this thread for the 1600? I would assume so but found no mention of it.
Shane

1968 SRL Project
User avatar
Linda
Fraternal Den Mother-RIP
Posts: 7807
Joined: Sat Nov 05, 2005 11:37 pm
Location: Los Angeles
Model: 1500/1600
Year: High Windshield-68-70

Re: How are your SU carbs set up? Looking for a baseline for adjustments.

Post by Linda »

I always assumed the .090 was for a 2000 nozzle for a 2000 carb, but not sure. Magic number for 1600 is .087 as you know.
I guess if there happened to be any debris or sediment at the bottom of the nozzles it could affect the fuel and also the needles. You can blast carb cleaner into the nozzles from the top and if sediment flies out there’s your answer. I have seen sediment in the fuel bowls so reasonable to assume it could proceed forward.
Linda
Might want to add your car model in your signature via Control Panel so we know what car you have for questions
I believe the 2k nozzles are different from the 1600 nozzle also
Sadly-Linda has passed away 2022. She was the 311's den mother and drove the first Rare-Parts ball joint project. RIP.
Post Reply