280zx su carb conversion

[carlos12245]

hi have a 1980 280zx na i was planning on converting to a turbo set ,but i have a set of su's sitting and i am want to to convert to them instead. my question is what is all needed to set them up

[datzenmike]

Probably need re-jetting for the increased displacement.

 

You will need the intake manifolds for the SUs, including the throttle and choke cables. Probably heat shields for them also.

 

Can't use the electric high pressure fuel pump. SUs work on about 1/10 the pressure. Get a 3.5-4 PSI pump.

 

You're in luck as the distributor is compatible. You may need to wire into the ignition switch.

[carlos12245]

ok thanks man i have choke cables will i need a shift and im having them rebuild from ztherapy i also have the manifold ,but will a stage one cam be ok with them and thanks for the info man

[datzenmike]

Run any cam you like but better to have less and want more than have too much and wish you had less. 

[carlos12245]

will i need a switch for the choke

[datzenmike]

No... they are cable operated. You said you had them.c

[carlos12245]

yes i do have them but the 240z has a lever inside the cabin for the choke

[datsunfreak]

but the 240z has a lever inside the cabin for the choke

 

Which you will need to source and install.   ^_^

[datsunfreak]

but will a stage one cam be ok with them and thanks for the info man

 

What is the advertised lift/duration? 

 

FYI the SUs carbs operate off vacuum. A "race" cam doesn't make enough engine vacuum to allow them to work at anything below 3000rpm. They will not idle with a lumpy cam either. Great for racing, annoying and bothersome on the street. 

[datzenmike]

will i need a switch for the choke

 

 

yes i do have them but the 240z has a lever inside the cabin for the choke

 

You won't need a switch.... you will need a lever.

[carlos12245]

ok thanks guys , yes i lever i ment sorry im new to the Zs use to have a gst eclipse ,but got interested in the Zs and ok on the cam a buddy of mine gave it to me ill keep that in mind . where can i get a lever

[HRH]

Oh, they'll idle, just not well. ;)  I had to have it set at 1200 rpm to idle right with dual SUs and the giant cam in the race motor in the 510 way back when.  Love the carbs still.  And who really wants to sit at idle all day?  I just throttled to the floor everywhere! :D

[carlos12245]

gotcha so far i have the dual su carbs with manifold ,choke( no lever),mechanical fuel pump, but i heard i can use my stock pump but ill need a fuel press regulator, also off topic ive gotten an oil cooler and msa headers ,but the carbs are what have got my attention i want to preserve the soul of the car which is why i canceled the turbo swap ,but thanks guys

[carlos12245]

also what do i do with the ecu

[datzenmike]

Easy enough to just leave it where it is..... or rip it all out.

[carlos12245]

does it have any part in the conversions ,like one of the sensors on the thermostat housing or is that ok

[datzenmike]

Well there is the water temp sender for the dash gauge, not to be confused with the one for the EFI. Likely in the thermostat housing and not worth removing just to plug the hole. Haven't checked but all the injector wiring, dropping resistors, TPS, MAF (etc) wiring may have it's own harness that enters the cabin on the driver's side? to the ECU. You could remove it all.

[carlos12245]

ok i just remember one of the sensors goes to the ecu from the thermo housing but not sure , i got a new housing and im not sure if the sensors are bad just found gas in my oil ,havent converted to the su's yet