Poor Running ?

On standard SUs the needle shoulder should be flush with the base. On 240Z carbs the shoulder is visible because the piston has a groove across the middle - collar is still flush with the true base of the piston.

SU needles should have the reference number stamped into the collar area but this may have been worn away. A good starting point is the old favourite for 1.75" carbs, the SM needle - available from stock at MJP (!).
For 2" fixed needle carbs use OA7; for 2" swinging needle try BAR.

The blown areas on the exhaust parts of your manifold gasket are typical when using the standard Nissan gasket with a header manifold. I stock the gasket supplied with the MSA headers we sell.
 
900ss said:
man7.jpg


Standard 240 carbs had the needle sticking out this amount so this is a good starting point when you have sorted the bottom out.
How long has it had these carbs on & did it run OK to start with or is it a new car that already had them on & it was never running right?
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Wyn, I told ya there was some thing wrong, take some advice, go to southern carbs in London SW19, get them rebuilt properly or go to tripples of FI, spend ya dosh once mate.;)
 
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Mr Ex said:
is it a new car that already had them on & it was never running right?
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Yep, run sh*t from day one when I bought it.
Still that's what you get for trusting peeps
dowa.gif


Anyway after speaking to the chap at Burlen and having now sussed the carbs as being Rover P6 2” HS8 fixed needle SU’s it seems the jets have been re-sized as have the needles. Not that that’s much, but they are re-sized as in they are the “not meant” for those carbs.
Anyway I’ve ordered new needles today and also have some jets coming but the needles will need to modded from sprung type to fixed before I can use them
Will it ever run right again lol, soon see :D
 
Jets n needles arrived from Burlen, as did a few other Z bittys from Mr F :thumbs:

Has anyone ever modded SU needles like these before as this is a new one ta me lol

As you can see the old fixed needle on the far right doesn't have the washer/ top hat
I know I need to remove that upper top hat section, but has anyone any tips, apart from don't bend it lol


newnee2.jpg


newnee1.jpg


Also the new bearings are slightly diffo as the brass sleeve is a much tighter fit in the alloy bush. Either that or the ol one was worn to fook lol :eek: :D

newnee3.jpg
 
My first reaction to the needles is that they are wrong. Get back to the supplier before you do anything with them.
 
For 2" fixed needle carbs use OA7
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SU part number AUD 1277.

Early Rover carbs have 0.090 jets as standard and these are usually modified to 0.100 series for use on Zs. The OA7 needle would be for use with the latter...
Part number for 0.100 jet is CUD 2752.

Info as per Steve Jones article in Z Club magazine Autumn 1987 - perhaps this could be scanned from the archives and added to Tech Articles? I believe Burlen used to make reference to a copy of this article when dealing with 2" SU Z related enquiries...
 
Cheers Mike, think I’ll try the OA7 needle next
Would be nice if someone could scan that article as this SU lark is new to me
Still shes all back together now and running miles better.
So far I haven’t driven it but its certainly not spitting back or running on anymore
Saying that I’m sure its still to rich on tickover. Might lower the needle to were it was before lol :unsure:

Btw, just incase someone else needs to mod a needle this worked well if you have nothing else to hand ...

Secret tool :D

http://img.photobucket.com/albums/0703/900ss/260z/bay1.jpg

Place the needle in a snug fitting brake pipe n just tap the needle down. Top hat just pops off.
Bingo and not a mark on them :)

bay3.jpg
 
Well done!

I misunderstood I thought the Top-hat section was part of the needle not a separate collar.
 
Lol so did I :eek:
I took it just the top washer part would pop off leaving me to file the rest down :confused:

Was I happy when it came off as one :)
 
Time for an update
Atlast I got to drive it today and guess what :eek:
It still missfired at high rpm lol :eek:

Still I took it for a blast whilst the sun was out n then decided to fit some new HT leads I had brought.
After fitting those I took it up the road n the thing actually reved over for the 1st time, pulled like fook after 4k aswell!
Fantastic I thought, at last it revs. :thumbs:

Guess what, I got to the end of the road and the misfire came back lol :confused:

Starting to think this is electrical again.
Cap, plugs and arm next n if they don’t work its back to square one n change the dizzy :conf2:
 
900ss said:
Time for an update
Atlast I got to drive it today and guess what :eek:
It still missfired at high rpm lol :eek:

Still I took it for a blast whilst the sun was out n then decided to fit some new HT leads I had brought.
After fitting those I took it up the road n the thing actually reved over for the 1st time, pulled like fook after 4k aswell!
Fantastic I thought, at last it revs. :thumbs:

Guess what, I got to the end of the road and the misfire came back lol :confused:

Starting to think this is electrical again.
Cap, plugs and arm next n if they don’t work its back to square one n change the dizzy :conf2:
Click to expand...

Before you do all that try a different coil.
 
Nigel Brook said:
Before you do all that try a different coil.
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Cheers Nigel, I already tried another coil before, but just incase you were right I tried a 3rd just to be sure, but it still missed the same.
Was an elecy Ford coil (all I had to hand) but I cant see that making any odds?
So I fitted a new cap, rotor arm n tried that
Guess what, still the same
Onto the dizzy next
Fitted the new elecy 2.4 Laurel dizzy I bought off ebay n its still the same lol
Tried another set of plugs …… still the same lol
They way the car misfires/ cuts out at high rpm is just like an ignition fault, almost as if the ignition is killed for a split second.
Odd thing is first thing this morning when I first drove it it would rev to 5.5k+ but within a few miles it got worse n ending up missing at 4.5k. Leave it 10 mins after trying a new part n would do the same again each time.
Run out of ideas n things to change now lol :conf2:
 
If you have messed with the carbs chances are that it's fuel related missfire. Not sure of the best way to check but you could drive it flat out until it strts to missfire then with your foot still hard down on the accelleartor pedal switch the ignition off. Pull the spark plugs and see if they are wet.
Do you have an electric on mechanical fuel pump?
 
Car uses an elecy Facet pump
The reason I’m thinkin electrical n not fuel is the way the car misfires at more or less the same rpm each time, no matter what gear, load or speed. Will even do it in neutral but to a lesser extent.
All the plugs seem the same colour so I cant see it being one carb at fault?
Also I don’t believe it can be fuel as the instant I change gear and floor it again it pulls like a train. If it were fuel starvation? Surely it wouldn’t pick up instantly each time?
Yes I pulled the carbs apart, but I cant see anything amiss now?
Obviously I’m assuming the car was set up and ran fine before I brought it.
One thing I’ve still yet to check is the fuel flow from each fuel line to the carbs
I cant see it being that but its something to do next time lol
As for the ignition I’m not sure what I can do there but I’ll take a look.
 
Paul I think it was fourways who fitted the dizzy, coil etc so yes the resistor has been removed by them I guess?
As for the rev counter it dances about when it misfires
 
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