240z SU Carbs P79 Head, Required Gasket

Evanso · Oct 2, 2020

Hi

Going to be putting 240z SU carbs on L28 with P79 Head and I have a couple of questions. If anyone has any advice I would greatly appreciate it.

Do I want to be using a gasket to fit the head or the carbs?

Also what needles do people recommend for a SU L28 combination or am I okay using the stock ones?

Will I need to run a return fuel line?

Thanks

toopy · Oct 2, 2020

Evanso said:
Hi

Going to be putting 240z SU carbs on L28 with P79 Head and I have a couple of questions. If anyone has any advice I would greatly appreciate it.

Do I want to be using a gasket to fit the head or the carbs?

You should have an isolator block for each carb, they go between the carb and the manifold, i think they are approx 15-20mm thick to reduce heat transfer, and you need a gasket for both sides, so 4 gaskets in total.

johnymd · Oct 2, 2020

Good question. That's a round port head so I'd probably use the one with round exhaust ports and the injection cutouts so that would be the 280 gasket.

johnymd · Oct 2, 2020

I haven't used a return line on my su's for a couple of years with no problem. Just use the cheap dial type fuel pressure regulator in the fuel supply hose.

Bazzateer · Oct 2, 2020

To answer your other question, you most definitely want to be using a gasket to fit the head. Or was that a typo?

johnymd · Oct 2, 2020

The question is clear to me. Gasket that matches the 280zx head face or 240z inlet manifold face.

Bazzateer · Oct 2, 2020

Reads different to me but maybe that's just me.

Evanso · Oct 3, 2020

Yes sorry I mean do I use gasket that matches the 280zx head face or 240z inlet manifold face.

Thank you all for the advice.

The head does have round exhaust ports and I have a 280z gasket so will use that and hope for the best.

Bazzateer · Oct 3, 2020

I don't know the differences involved but can you get the manifold and head ports machined to match? You could then make a gasket or perhaps modify a stock one?

Evanso · Oct 4, 2020

Going to try my 280z gasket as think that work. Otherwise, I may have to go down the machining route.

johnymd · Oct 4, 2020

I'd use the p79 gasket. It has round exhaust ports and 36mm inlet ports. The head and gasket does have cutouts for the injectors but after checking today it will still seal against the su carb manifold. Close but will seal.