L28E conversion to round top SU carb

Pedey · Post by **Pedey** » Fri Nov 16, 2012 11:08 am

Hi everyone,

As per my other tech help thread -

"Thanks for the replies - ok so just an update - I've decided it's time to ditch the EFI.

It's problematic and always makes me nervous any time I drive it because I'm not sure if the car is going to make it, aside from it running like crap/randomly not revving over 2g etc. After looking into the problem further, without discovering the cause of it not starting for sure I've also found broken and leaking injectors and other problems that will surely only get worse the older it is."

As the carbs are coming straight off Mikey's stock L24, I'm able to get everything I need - manifold, carbs, airbox, even an electric fuel pump. I've been doing a lot of research around and it doesn't seem if there's anything else I need, bar a gasket.

So, I have a few questions -

is there something I'm missing? Anything else that I may need for the conversion? Especially considering my car is LHD and does not have a choke toggle in the cabin.

Does anyone know exactly what gasket I need in order to cover the injector holes on my L28?

I'm a bit hazy on exactly what has been done to my L28, but it definitely has some form of angry cam and extractors - compression appears to still be low though and the car only made 100hp at the wheels on the dyno as is. With that information, will I need to modify the carbs with new needles/jets or similar to get it running right? Will it run, if not perfectly, with the stock needles that are in the carb currently?

I know there are a few questions there, and I've done a bit of research on the subject, but I'd much rather trust my local brethren who have local experience.

Thanks very much in advance!
Pedey

us2 · Post by **us2** » Fri Nov 16, 2012 12:16 pm

It's all been done before. You stock 240 carbs will work well . So they say.

http://www.google.co.nz/url?sa=t&rct=j& ... vg&cad=rja

Bruce Palmer on that forum is from Z Therapy and has the knowledge on SUs.

Jabo · Post by **Jabo** » Fri Nov 16, 2012 3:02 pm

I Have just been though this swap you need to use the l26 gasket I think from memory

ZMAD · Post by **ZMAD** » Mon Nov 19, 2012 10:28 am

I think you will need a twin choke setup for easy starting.

Pedey · Post by **Pedey** » Mon Nov 19, 2012 1:41 pm

Thanks for the replies guys,

Picking up an L26 gasket today and I'll look into the twin choke thing tonight. Thanks!

us2 · Post by **us2** » Mon Nov 19, 2012 2:02 pm

Yeh the SU's need a choke cable as there is no accelerator pump on them.

ZMAD · Post by **ZMAD** » Mon Nov 19, 2012 6:23 pm

I actually have the twin cable and knob (not perfect) from my 75 260Z. Where you would put it, who knows. A thought I just had, twin stepper motors activating the choke with a control in cabin allowing adjustment. A future project for myself maybe.

Pedey · Post by **Pedey** » Mon Nov 19, 2012 11:26 pm

bummer - the fuel lines are different diameter but most importantly the carb manifold fouls up on the headers and makes them about 5-10mm too high.

old_datto_fan · Post by **old_datto_fan** » Mon Nov 19, 2012 11:36 pm

Sounds to me like you need a set of Triple carbs to match the rest of the mods you are doing.

You will not be able to flow enough through twin Hitachi/SU type carbs to make full use of the cam and extractors so just bite the bullet and do it properly!

And then providing you get someone to set them up properly you will get the performance plus the lovely sound triples make. Better than any car stereo.

hamish262001 · Post by **hamish262001** » Sat Dec 01, 2012 4:24 am

Pedey wrote:bummer - the fuel lines are different diameter but most importantly the carb manifold fouls up on the headers and makes them about 5-10mm too high.

you can grind down or file the manifolds to get them closer together