swap 3-screw SU set for 4-screw?

[epsark]

Thanks Mitchell! The link you provided shows a good picture and it shows that it is the SK version. I'll be getting that one and the DVD that Ztherapy offers. Both great buys in my opinion, as I had no good reference material for a dual carb set up in my bug and the unisync was not worth the money or hassle to use.

[Bonzi Lon]

My experience,

New carbs (1980) 4 screw front, 3 screw rear, 96 miles on them then the car parked 26 years. Looked in front bowl, after gasket fell apart in multiple pieces, full of varnish. Tried getting rear lid off for 1/2 hour until it was decided surgery was needed. Trimmed enough to get the lid off, full of varnish and gasket parts.

Never been in a carb before 2006. Got the video, watched it twice, took both carbs apart, cleaned, reassembled and back on in under 3 hours. Fired right up, minor adjustments like the video showed. Found out the rear 3 screw was best at 2 1/4 turns down, front was 2 1/2 for plug color to match.

One other difference in the two styles is the choke cable attachment. The 4 screw uses a 'P' clamp with 2 clamping screws. The 3 screw carb has a single screw clamp attachment and has a steel cable stop swedged to the end of the choke cable.

Three weeks ago I changed out the above set for a set of rebuilt polished 4 screw carbs with cad plate attachments. Added a polished euro balcance tube and a polished valve cover. They were synced and set in less than 20 minutes. Light brown plugs.

My advise is get the video and either sync tool, these carbs are too easy, just misunderstood.

I remember seeing a motion emoticon (on here?) showing a SU carb working, at idle small amount of fuel flowing, choked the nozzle went down and more fuel flowed, at wot the butterfly opened, suction piston went up more fuel flowed. Anyone remember it or have it avaliable?

Bonzi Lon

[BTF/PTM]

Bonzi,

What did you trim to get that cover off? That's exactly what I'm curious about.

p.s. - contacting Ztherapy now to order that video =)

Edited May 24, 2010 by BTF/PTM

[Gary in NJ]

You don't need to trim the cover. Turning it 90 degrees and giving a bit of a tilt, it comes right out.

[Travel'n Man]

Remember how you got the cover off and the positioning - you will need to put it back on - be sure to order some gaskets before you take that cover off - you can order them through Z Theropy or directly from the Nissan warehouse from your local stealer.

[BTF/PTM]

I've ordered Bruce's "Just SU's" DVD as well as the other tune-up DVD, I figure it's a really cheap way to educate myself before I dig into the carbs. Soon as I can fix (or replace) the severely warped tail light housing flanges I'm currently dealing with and get the car put back together I can finally visit a fellow forum member who has offered to help me tune things up with all the proper tooling.

[Bonzi Lon]

Bonzi,

What did you trim to get that cover off? That's exactly what I'm curious about.

I didn't trim the lid. It was the ear with a hole sticking out above the lid. It is about 7mm long now, started about 12mm. I sold a set of 3 screw carbs and never thought to look to see if that ear was on them. :stupid:

Bonzi Lon

Edited May 27, 2010 by Arne

[BTF/PTM]

That's ezzakkly the protrusion I'm referring to, thanks! I wonder if that was part of the internal boring process that they later figured out could be done differently. I'd bet that there's a ball bearing plug at some point in that little hole; anyone know for sure? I can't smash my face down next to the carbs close enough to look.

[Bonzi Lon]

The hole is empty. There is the same protution on the other side of the carb, that is where the choke cable clamp is held on.

Bonzi Lon

[JohnnyO]

Eric -

I actually bought this one:

http://www.thezstore.com/page/TZS/PROD/60-9976

Did you need the Syncrotester too? What is it used for?