I'm planning to replace the Weber carb on my '67 wagon with a pair of SUs. The SUs were in a box of parts that came with another '67 wagon project. They were semi disassembled when I found them. I have had the throttle shafts replaced and the bodies rebushed and have most of the parts in hand but can't see how the choke linkage connects to the jets. The arms are there, one of them is missing a little bushing at the end, jets are new, but what holds the arm to the jet ? Most of the parts diagrams show what looks like a wood screw...

Thanks

Greg

I'm in the process of cleaning up the carbs and have several questions:

1) is worth taking the linkages apart to clean them up ? I gave them a little tug and they did not seem to want to come apart easily.
2) does anyone flatten the float bowls, lap the vacuum chamber to the throttle body, flatten the mounting flanges, etc. like you would on an AMAL Concentric ?
3) are you using in any grease or lube on the jet assembly, piston and dome, etc ?
4) is the float setting of 3/32" still good with non-oxy pump premium ?
5) what are you doing for air filters ?
6) are any of the SU manuals worth having ?

Thanks

Greg

4. don't see why the float height would change with premium, but I also see no reason to use premium, regular is fine in a well tuned engine.
5. You can do anything for air filters, I use the rectangular air box from a twin SU 140 volvos, this reduces engine noise quite a lot. Others modify the old air filters to hold new air filter elements, pretty much anything goes as long as it breathes enough.
6. the tuning protocol in the Haynes manual for 120 volvos works fine for me, if you search online you will find plenty of guides for tuning SUs they were on a ton of cars and tuning/balancing them is not that hard and fwiw if badly tuned/ balanced the car will still drive, just not as well.

Finally and most importantly, tuning the carbs is the last step of tuning the engine.....
1.valve clearance
2.ignition
3.carbs.
if you don't tune carbs last you are chasing your tail.
--
Patrick, '68 220 , '53 GMC 4104, '97 VW Transporter.

patrick wrote--"but I also see no reason to use premium, regular is fine in a well tuned engine."
I wouldn't necessarily count on that. A '67 or '68 B18 will have a compression ratio of 10:1 and premium was what they ran on "back in the day". With the alcohol diluted gas most of us have he might be able to use a mid-grade for easy cruising driving but I think regular would be pushing the envelope. These motors had run-on and spark knock problems to begin with.
Regarding Phil S's note about filter housings--'69 and '70 cars had Strombergs -- '71 and '72 had SU's. Individual filters as on the '67 and '68 look cool but the filter box I have on my '69 144 (w/SU's) makes filter changing a cinch and nets you an automatic "cold air intake" bonus that so many lust after. -- Dave

I'll just add that most of the air filter boxes I've seen are for Stromberg carbs, and do NOT fit SUs without modification.

Hi Greg,
In regards to question #5 about air filters for SU carbs, you might be interested in my "air filter conversion kits" I manufacture & sell on Ebay. They're $59.99 per pair and have a powder-coated blue finish and use replaceable elements, available at any auto-parts store, or on-line from many different sources. Saves money from now on at every filter change.
I keep them listed on Ebay most of the time. I'm in Spring Branch, Texas and can ship anywhere in the USA.

"Most of the parts diagrams show what looks like a wood screw..." That's exactly right. The lever lines up with a "boss" cast into the plastic part of the jet. The "bushing" is important because it spaces the lever properly to the jet--and allows motion there without binding. I have some spare "parts" carbs - which carb needs the bushing -- front or rear? If I have what you need I'll send it along for postage. Get back to me before there's a foot of snow on the ground--then all bets are off :-) -- Dave

Hi Dave, Thanks for the offer. The bushing is missing from the rear linkage arm.

I'll send you an email.

Greg

You can reach me at -----fastforwardphoto(AT)yahoo(DOT)com---or call six-three-one 968-8933. I checked--do have the part available. -- Dave

The choke linkage retaining screw is a pan head Phillips wood/sheet metal screw.

The spacer/bushings on the end of the choke linkage arms are important and something needs to be there to hold the lever away from the jet tube.

FYI, the jet tubes are handed and it is important to install the correct jet tube for each carburetor.

If you are using original SU jet tubes, they have a colored band on the hose to help distinguish which jet tube goes where. A yellow band for the front jet tube and a red band for the rear.

I have seen more than set of carbs with damaged choke linkages because the wrong jet tubes were installed and someone forced the choke linkage to fit.
--
Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Thanks Eric, Good to know about the colored bands on the jets ! The screw was a bit of a puzzle because the hole goes all the way through the plastic on the jet but the parts list didn't show a nut for it. I mean, who would use a wood screw on a twin carb set up ?

Greg

Greg;

In the first place, a self-tapping (sheetmetal) screw into a maleable plastic actually works by the identical mechanism that a nylock locking nut does...in the second place, I've never seen one back out due to vibration...it does take significant and deliberate loosening torque to remove, so although low budget, it does seem to be an perfectly effective solution, so I'm really OK with it...

On the other hand...I would like to see the Jet Supply Tube be held a bit more positively into bottom of Fuelbowl than by the minimal compression force of the seal...I mean it doesn't take much more force than brushing up against it in the wrong (pulling) direction to remove it...

Cheers

Someone who cannot keep a normal nut and bolt from coming loose with a lot of use. No room to stake the nut.

Believe it or not, I remember the first time I saw nylock nuts was in Popular Mechanics in the '60s - long after SU carbs were regularly used in British cars.

Some frustrated engineer went to his scrap parts box.