My Zed's performance has deteriorated over the past few months, and I believe it to be running too rich (due to the petrol smell, dark blue smoke and backfiring under hard acceleration, it ran fine before) So i think I need to tune, and the options are either pay some one to do it (approx 300AUD) or buy the colourtune and unisyn and do it myself. I want to do it myself as this is one of the reasons I bought the car, to work on, but my dad thinks it would be too hard for me, and I have haeard it is quite difficult as well, but I still want to tackle it. What do you guys think?

Alan, Australia

 

Assuming all components are in good nick, it's a piece of cake. Start with the timing/points gap/dwell.

Then move on to setting the mixture to get the best plug colour on 1/2 & 5/6 (this puts 3/4 a tad rich). Generally that puts the power balance pretty close. The easiest way to check what direction you need to move (which is a good starting place for the mixture tune-up) is to pull 1 lead at a time at a known (say 1500rpm) engine speed. You then simply take note of which cylinders are not pulling their weight & take it from there. Chances are you will notice that 1 carb is doing more work than the other.

If you can't get a satisfactory result, then you will need to look at the carb pistons/needles & float level. All the good Datsun books give a guide to the proceedure.

Ben
Adelaide
Sth Australia
IZCC#1902
240Z L31ETT
L28ET MR30 Skyline
FJ20ET DR30 Skyline RS-X

 

This is not a major job. Do like everyone else said. Start with plugs cap points wires. Then the carb adjustments i have learned to be patient and only make small adjustments. It takes time and practice dont get discouraged use patience. The first time I did this it took all day but I was 16 and didnt have any idea what to do.
Enjoy this is why we own these old Zeds.

Friends dont let friends drive anything but a Z.

 

Alan if you have any friends who have a Z and know how to tune the carbs etc.. the best bet would be to kindly asked them to show u how to do it, its very simple, and i can easily do it now in around 15minutes. compared to 3 hours teh first time i did it.. hehe

also check ur SU oil, use ATF or buy some SU oil from ur local carburator shop

<font color=blue>76 260z</font color=blue>
The NiteRider

 

Thanks guys, i'll try that. I need to wait till I've finished exams though, which will be in about 3 weeks.

Ben, when you say pull the plugs I assume you mean pull of the lead to the plug so the spark plug is not working? How do I tell if the carb is pulling its weight, will it stall if it isn't? And when you say keep it a a known revs, should I just wedge the accelerator down with a brick to the required revs to keep it there?

once again thanks for the help

Alan, Australia

 

Is all this stuff in the haynes manual about points/dwell etc?

Alan, Australia

 

Alan don't wedge a brick on the accelerator you will end up revving it too high I'd say. You can do it from the engine bay
I think what he means is set the idle up high so u can hear how much each carb is sucking air then match them and using two screw drivers drop them both down to 800 rpm. Also does anyone else have that problem where u stop at lights and the idle is high and u give it a tap and it drops to about 800rpm where it should be? What sticks and how can I fix it seems to be a common Z thing.


Gavin,
Melbourne
Australia
72' Datsun 240z