flat top carbs

[dpellizzaro]

hi guys just installed a pair of hitachi flat top su's from a 260z onto my l28. i was wondering where a couple of the vacuum hoses go and i have struggled to find any diagrams or any thing to point me in the right direction. Also is there a tuning guide for these carbs?

 

Any help would be appreciated.

 

cheers

David

[Scoota G]

Hmmmmm, shouldv'e put your flame proof suit on first.

[Enzo]

Hi Mate,

          I have the Flat Top carb tuning manual but can't compress it enough to send through the Forum because of the 256kb limit. If you can supply an email address I will send it to you.

As Scoota is inferring, Flat tops are not the way to go. You should purchase the earlier 240z (pre- emission) round top carbs. These are a much better option. If not available through the forum, ebay should be a second choice.

David

[dpellizzaro]

thanks message sent.

 

i know that they have a bad rep, but i only have these to work with for the moment so i will try to make it work.

 

Does anyone know where the vacuum line from the distributor connects to the carb?

 

cheers

david

[zzzzed]

This may help a bit

[Scoota G]

Sorry for the cold reply but just look at them.!? It looks like a Transformer spewed. I have a set here on an L26 if you need bits. Seem to be in good nick.

[neRok]

Ive just put some twin carbs on mine. The vac hoses are quite basic. You need 2/3 at the bare minimum;

- 1 small for dizzy

- 1 small for auto transmission (if fitted)

- 1 big for brake booster

 

You also have the PCV valve (big pipe) which goes to the breather on the block (sometimes the rocker cover in L28 efi from my research).

 

You may have some extra for any air con and emissions.

 

The emissions gear is likely what gives these carbs a bad wrap, I dont know much about carbs or SUs, but i noticed they are very basic. If you removed all the emissions gear, I cant see what would make a round and a square top any different. At the end of the day, the piston moves up and takes the needle with it, which allows different amounts of fuel in. Unless they have a crappy needle that doesnt let much in, they are basically the same. Maybe the manifolds are different shape too?

[zzzzed]

Flat tops are so very different to round tips. Emission gear or not.

[dpellizzaro]

thanks guys, those photos are gold... i have been google image searching so many different things to get the right angles. I have all the emissions stuff stripped off mine and they seem to have been recently serviced and are in good clean condition. Hopefully they work well and i wont need to worry about round tops.

 

either way im very happy with the response's and hope i dont need too much more help.

 

cheers

david

[Gyzmo]

If you need to tune your carbs, read my article posted on ZParts.com

http://www.zparts.com/zptech/articles/mal_land/ml_sucarb2/images4/SUcarb_111601d.htm

 

The flat top carbs are not tuned the same as the Hitachi Round Tops and SUs.

 

In the pics provided you can see a large white screw at the front LH side of the carb (behind the air filter).

This screw bleeds air into the side of the carb to lean out the mixture.

 

The jets are fixed - not adjustable.

 

Don't use light duty oil in the dashpots...

Why?  Read my article...