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Thinking of changing a few things..
https://www.ausmini.com/forums/viewtopic.php?f=2&t=87650		 Page 1 of 2
Author:  jprior2912 [ Wed Nov 05, 2014 9:11 pm ]
Post subject:  Thinking of changing a few things..
Hi guys

So I was still having an issue with my car not holding its idle even after adjusting it up.

So I decided to pull my spark plugs out and give them a check, the below picture is what I found, they're quite... black.. right? I also checked the brand and type (they came with my engine) and they are Champion N9YC. What are they equivalent to that in an NGK? With that plug the colour it is, would a hotter plug help? I don't think the mixture is rich because when I make it even one flat more lean it misfires but as it is it accelerates perfectly with no hesitation. I've also had the needles in the carbies changed to suit my engine (sorry I don't know what needles they are)

I was also thinking of getting a set of GR dual induction leads, as mine are 'Racewire' Brand and maybe that could help.

Maybe also a new coil, at the moment it is a lucas 105 sports coil, but I've heard good things about the GT40, or GT40R?

Image
Author:  drmini in aust [ Thu Nov 06, 2014 5:42 am ]
Post subject:  Re: Thinking of changing a few things..
Plug doesn't look too bad, at least it's not wet! Might just be running a little rich.

Champion N9YC equivalent in NGK is a BP6ES.
A BP5ES is 1 step hotter, is recommended these days for use with unleaded fuel particularly for traffic use.
Author:  drjbeam [ Thu Nov 06, 2014 6:18 am ]
Post subject:  Re: Thinking of changing a few things..
http://www.sparkplug-crossreference.com/
And there is crossreference pdf on the net id put some links up but they download straight away
Author:  jprior2912 [ Thu Nov 06, 2014 8:50 am ]
Post subject:  Re: Thinking of changing a few things..
drmini in aust wrote:
Plug doesn't look too bad, at least it's not wet! Might just be running a little rich.

Champion N9YC equivalent in NGK is a BP6ES.
A BP5ES is 1 step hotter, is recommended these days for use with unleaded fuel particularly for traffic use.


Thanks Doc

My mixture seems to be a mystery, if I make it any more lean (by one adjustment) I get a serious misfire between 1600-2000rpm under acceleration and load, once it gets over that rpm it's fine - It's running brilliant now - besides when I sit at traffic the idle starts to drop off nearly straight away.

My head is converted to unleaded and I run Caltex 98. Does the hotter plug help with fouling? Also would it make my engine actually run hotter too?

drjbeam wrote:
http://www.sparkplug-crossreference.com/
And there is crossreference pdf on the net id put some links up but they download straight away


Cheers that's a good site - I found similar ones online but they didn't give me as much info.
Author:  timmy201 [ Thu Nov 06, 2014 9:32 am ]
Post subject:  Re: Thinking of changing a few things..
It could be that you might need a slightly different needle, or get a professional to re-profile your current one. The needle will change your mixture at different points in the rev/load range. It could also be down to the idle settings...

If you pull the plugs out after idling, it will show the mixture at idle. If you run the engine under load and shut off the engine and check them it will give you an idea of the mixture when driving.
Author:  jprior2912 [ Thu Nov 06, 2014 10:14 am ]
Post subject:  Re: Thinking of changing a few things..
timmy201 wrote:
It could be that you might need a slightly different needle, or get a professional to re-profile your current one. The needle will change your mixture at different points in the rev/load range. It could also be down to the idle settings...

If you pull the plugs out after idling, it will show the mixture at idle. If you run the engine under load and shut off the engine and check them it will give you an idea of the mixture when driving.


Thanks Timmy

I might give different plugs a go - probably cheaper than getting my needles reprofiled. It's a shame that the cars runs perfect except for idle. I've recently upped the idle to about 1000-1100rpm, sits there for a few seconds sounding nice, then starts to drop and the techo starts to jump a bit

EDIT: Also - in terms of coil, I have the powerspark elec ign in a 59D body. Do I need a GT40, GT40R, or GT40RT?
Author:  drmini in aust [ Thu Nov 06, 2014 10:47 am ]
Post subject:  Re: Thinking of changing a few things..
What carby and air filter are you running?
And what needle is in it now?
if it's an HS4 carby with sports filter, the stock needle is too lean. Symptoms you have.
Try a CP4,or a 6, or 7.
These are fixed needles (which I prefer)- I have no idea what the swinging needle equivalents are.
Author:  jprior2912 [ Thu Nov 06, 2014 10:52 am ]
Post subject:  Re: Thinking of changing a few things..
drmini in aust wrote:
What carby and air filter are you running?
And what needle is in it now?
if it's an HS4 carby with sports filter, the stock needle is too lean. Symptoms you have.
Try a CP4,or a 6, or 7.
These are fixed needles (which I prefer)- I have no idea what the swinging needle equivalents are.


Yeah I'm using twin HS4's (apparently off of a ex police cooper S) with K&N Cone filters I had them refurbed at SU midel in Sydney and told them my engine specs and told them to fit an appropriate needle. But I don't know what needle is actually in them now tbh. Is there a way of checking? Is changing needles a big job?

So, with a CP4, 6 or a 7 - does the bigger the number mean the richer the needle gets?
Author:  drmini in aust [ Thu Nov 06, 2014 10:58 am ]
Post subject:  Re: Thinking of changing a few things..
Police pack twin HS4s had CP4s in them, stock. Fixed needles.
When I had a set on Barney's 1293 I fitted no 6 instead, the mixture graph was then a straight line at full throttle on the dyno.

Put an A/F meter on, and see what mixture you've got.

[edit] load http://www.mintylamb.co.uk/suneedle/
select .090" jet size, and put these needle numbers in. You can then see the differences.
Author:  timmy201 [ Thu Nov 06, 2014 11:09 am ]
Post subject:  Re: Thinking of changing a few things..
The numbers are stamped on the end of the needle that is held into the damper. It has a little grub screw to undo to get the needle out. You'll have to be very careful not to bend the needle. I couldn't get one of mine out, but it would spin around, so I pulled out the grub screw and I could read the number through the hole.

This is a good example of the "needle stations" that are on the mintylamb site and what to look for
Image

Edit: I've got a spare carb in my shed if you want to borrow it on the weekend to see how they all work?
Author:  jprior2912 [ Thu Nov 06, 2014 11:45 am ]
Post subject:  Re: Thinking of changing a few things..
Thank you guys, great reference there. The size of the needles does make a big difference it seems.

This might seem like the most basic question EVER. But Timmy you said that the needle is on the damper? So I just went out and unscrewed the little black cap thing the top of my housing (that's the damper screw, yes?) and as I pulle it out a long silver thing came out with it.... Is that the actual needle that came out attached to the damper screw?

Thanks for the offer! I'll see how I go here in the next day or so, if I can't figure it out may be that would be a good idea.
Author:  phillb [ Thu Nov 06, 2014 11:53 am ]
Post subject:  Re: Thinking of changing a few things..
What specs are your engine. I can look what needles were in my 1.5 twins when I had them fitted.

If u do remove the needles be very careful. I use soft (aluminum) vice grips in a bench vice to grip the needle and then twist and pull the piston gently. They should come out easy as they haven't been in there for decades.

It's not that easy to read plugs now days with unleaded fuel. They will often be black from idle anyway I think.
Author:  jprior2912 [ Thu Nov 06, 2014 11:56 am ]
Post subject:  Re: Thinking of changing a few things..
Hey Phill

1275 A+ Metro turbo block, bored to 1310cc, GR RE83 Cam with converted unleaded head and slightly bigger valves. Bout it'

When I unscrewed the black plastic screw on top of the carby it all seemed to come out fairly easily.
Author:  timmy201 [ Thu Nov 06, 2014 11:57 am ]
Post subject:  Re: Thinking of changing a few things..
SU carbs are a bit confusing in regards to terminology as different people call them different things..

To get the needle you'll remove the top (item 15)

If you undo the three screws (item 20) on the dashpot (or vacuum chamber) and remove the dashpot. You can then very carefully pull out the damper (item 12) directly upwards in the axis of the carb.

The grub screw is number 13 and the needle will be sticking out the bottom of the damper.

Image

There is some good reference info here
http://sucarb.co.uk/technical-carburetters-introduction
Author:  jprior2912 [ Thu Nov 06, 2014 12:03 pm ]
Post subject:  Re: Thinking of changing a few things..
timmy201 wrote:
SU carbs are a bit confusing in regards to terminology as different people call them different things..

To get the needle you'll remove the top (item 15)

If you undo the three screws (item 20) on the dashpot (or vacuum chamber) and remove the dashpot. You can then very carefully pull out the damper (item 12) directly upwards in the axis of the carb.

The grub screw is number 13 and the needle will be sticking out the bottom of the damper.

Image

There is some good reference info here
http://sucarb.co.uk/technical-carburetters-introduction


Thanks Timmy, haha I was way off what I thought it was!!

That diagram makes it look very scary to pull my carbies apart. I might leave it until after Sunday's run incase something doesn't go exactly right. I'm not missing it!
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