8/71 SU Carb Help, Float Bowl Adjustment

[Captain Obvious]

It sounds like empty bowls to me.

Check the float bowl level with a clear tube. Don't just measure something mechanical on the float itself and assume that will result in a correct level. You actually have to measure the level directly.

Do you have the little screen filters in the carbs? Maybe they're clogged?

[AK260]

It sounds like empty bowls to me.

Check the float bowl level with a clear tube. Don't just measure something mechanical on the float itself and assume that will result in a correct level. You actually have to measure the level directly.

Do you have the little screen filters in the carbs? Maybe they're clogged?

 

Wot he said!! [emoji1375][emoji1375][emoji1375]

 

I do think you are chasing more than one root cause here.

 

Reading your first post, my immediate reaction was intake air / vac leak. It has caused me no end of headaches and cost me £££s changing the entire ignition system to no avail. But once I found the leaks (yes multiple places) the car came back to life.

 

FYI - the places I found leaks were: carb dome to main body, carb throttle shaft cap, intake manifold, brake booster vac line (the wiggly one that is NLA and hard as a rock given its age). Bear in mind my Z therapy carbs are a few years old now so the paste on the throttle shaft cap had heat cycled a lot. Take nothing for granted and check all potential areas for intake leak. The carb dome to body, looking at the diagram of its operation, should in theory not have caused an issue but boy did it improve the carbs’ operation once I made my own gaskets for them.

 

Reading your later posts I’m pretty sure you also have a fuel starvation issue at the same time. Blow out your fuel lines with compressed air and do the things the captain and others have recommended. I have a clear fuel filter and found lots of black fish in mine. Taking it apart, i found them to be soft fish, not rust. Rock hard rubber fuel lines from 2006 (under the car where the PO had performed a hack and added lots more rubber) had started to break down from the inside.

 

 

Ps. Yes that is fuel lines sitting tightly on top of the rear ARB!! [emoji33][emoji33][emoji33][emoji33]

[Pinbill]

Hey guys,

I was out in the garage this morning.

I did a compression test without oil in the cylinders, the carb bodies closed, and the motor cold. I got 137 / 141 / 141 / 135 / 132 / 135. I tried putting oil in the cylinders but the numbers were all over the place and I didn't want to put too much in and bend a rod. I suspect the numbers will be better if I do it again with the domes off and the slides off. The odometer is at 99k.

I ran two hoses into a container to test the fuel pump. Its getting plenty of clean fuel out of the fuel pump to the carbs.

I am assuming the thimble fuel filter would be in the banjo bolt on the fuel bowl lid. The banjo bolt was too stuck and I didn't want to break anything. I did back flush the fuel bowl lid with carb cleaner and compressed air. I blew it into a paper towel to check for debris. I didn't see any debris or anything come out. If there is a filter in the fuel bowl lid it is clean.

I blocked off all the vacuum connections to the smog pump. The two smaller gaskets on that same rail are new and tight. I checked the tightness of my carb blocks and gaskets. My intake and exhaust manifold gasket is new and tight. All my vacuum hoses from the vacuum booster (the expensive ones) are new. I sucked in on the distributor vacuum line. The distributor is holding vacuum. I was very thorough when I had the intake manifolds off. I tested the vacuum again when the car was "idling" and I got 10-12#. Does the brake vacuum booster ever leak?

I am headed to the hardware store right now to get a nipple for the fuel bowl drain to do the clear line test.

Bill

 

 

 

 

 

 

[Mark Maras]

 Those compression #s look low to me. I would expect #s in the high 160s. Did you hold the throttle wide open when you were turning it over?

[Pinbill]

I didn't hold the throttle open. I didn't use oil either on the compression test. I will do it again after I set the float bowl.

Found a 8mm x 1 threaded banjo bolt that I used once to set the transmission on my old w123 mercedes. That's why I don't listen to anyone who tells me to throw stuff away. LOL.

The reading is 26.5 mm from the top of the fuel bowl. I am 3.5mm too low in the fuel bowl. I will straighten it out to 23mm below the fuel bowl and report back.

 

Edited July 27, 2020 by Pinbill

[Pinbill]

Ok,

I just did the rear bowl. The car ran. I feel like when I do the front bowl it will be good. I will post back up with an update in a little bit.

Bill

[Mark Maras]

 Be sure to reset the nozzles to 2 1/2 turns.

[Pinbill]

Ok,

I did the rear bowl and the car ran better for about 15 seconds. I shut it off and checked the front bowl. The front bowl was good. I started it and it is back to running like garbage. I ran the car with the sight line attached to both bowls and the level didn't drop at all while idling. It seems like it getting enough fuel.

 

 

 

[Pinbill]

Does anyone know what voltage I should be getting at the resistor and coil?

Edited July 28, 2020 by Pinbill

[Pinbill]

Got the car back from Jeff at Rallye Sport in Westminster. It was the wiring in the distributor. While it was there he adjusted the valves, timing, dwell, ect.. It is running much better that I could have adjusted it. It was the way to go bringing it to a guy who has the touch. He has been working on these motors for a 45 years and it is running super smooth. He is a very good guy. I am very happy. Thanks again for helping me with the information.

Bill

[siteunseen]

When I first bought my orange 240 it ran like poo poo. Could not figure it out for the life of me. There was a black wire loose on the original points dizzy. Got that secured and it came back from the dead. Then I went to the ZX electronic distributor. Zero problems and runs better in my opinion. Cost $150 for the distributor and lower amp coil, bigger cap and button.

One of the top 5 upgrades to me.

[rcv]

On 7/24/2020 at 7:44 PM, Pinbill said:

I found this spec in the service manual and tried 10.31 because my car is 8/71 build date. Should I use the 14.28 setting?

 

Hi Bill, sorry to dredge up an old thread, glad to hear things worked out for you.  Do you have a link to that service manual you go the float level diagram from? I haven't seen that figure before in the FSM I've been referencing (http://xenonzcar.com/s30/files/FSM L20aL24engine.pdf) so I'm curious to know where it's from.