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MG Midget and Sprite General - K&N AIR FILTER help please

Hi. I have just put some K&N air filters on my Midget 1500 and I love the sound of them but haven't noticed any more power. I have read on here that the needle and spring will need upgrading. But I can't find looking through the archive any where to what upgrade can any one please help so I can order them. Many thanks.
n Allen

TBH, with a 1500 you REALLY need an extractor exhaust manifold before you should start thinking about different needles. The Midget 1500 manifold is the old Triumph Herald manifold and, as such, is extremely poor. The Spitfire 1500 had a way better manifold but even THAT needs changed before changing carb needles!

Once that is done then try the AAQ profile. Personally I would also replace the Wax-Stat jets with plain jets.

After that, try the heavier 8 Oz yellow damper springs.
Deborah Evans

I guess the ex-tractor exhaust manifold is needed because of that engine's ancestory?

OK - I'll get my coat...
OrangeSpyderMan

If it were the TR2/3/4 engine aye, but the small Triumph 4-pot never had anything to do with tractors.

So, good joke, badly applied! :)
Deborah Evans

I guess that doesn't even get me points for trying. Oh well, I said I was getting my coat :)
OrangeSpyderMan

no just putting K&Ns on you probably wont notice more power, lovely noise tho' and don't nedd cleaning for 50,000 miles

you could try adding the stub stacks too even more noise

the best way to get more power intially and inexpensively to to carry out full and proper servicing, maitainance and repairs as per owners Handook - (ref: 0058) http://www.mgocshop.co.uk/catalog/Online_Catalogue_Handbooks_5.html

then as part of the service after attending to other items you might adjust your carbs to suit your K&Ns (and stub stacks, different needles are not always necessary)

when your car is full and properly serviced then the whole car will go better not just the engine

if after this and subject to your engine and car being in good condition then you may get the best out of by having a rolling road tune up

after this it's best to upgrade items as they come up for replacement as getting more power gets very expensive

Nigel Atkins

Unless the standard air filter and box is very, very efficient, fitting K&Ns reduces the pressure drop on the jets resulting in a weaker mixture. This usually requires a richer needle to compensate, something like an AAM from (poor and getting worse with age memory). Deborah is spot on saying dump the waxstats or at least drill em to let the wax out and render them inoperable. You would expect 3-4 bhp at the wheels from the K&Ns, not really noticeable with around 46-48 at the wheels to start with, but every little helps.

Peter
P Burgess

Thanks for the advise everyone. I think I might start with replacing the Wax-Stat jets with plain jets. I this an easy job?
n Allen

"This usually requires a richer needle to compensate, something like an AAM from (poor and getting worse with age memory)."


Peter,

From experience, AAM is generally what you use on a Triumph 4-pot after you've done induction, exhaust, head work (std valves) and a fast road cam.

The basic progression for the 1500 is:

ABT/ADN - AAQ - AAM - AAL
Deborah Evans

Deborah,

My 1500 has had no mods other than a pair of K&Ns fitted and still has the original exhaust manifold. The previous owner fitted AAQ needles and i've always thought that it ran on the rich side. Would you consider that to be the right needle?

Dave
D MATTHEWS

No Dave, the AAQ will be way too rich for a stock motor on K&Ns wspecially at the top end.

You want to be using ABT with fixed jets (or ADN with wax stats) and richen up by a flat or two.
Deborah Evans

"I think I might start with replacing the Wax-Stat jets with plain jets. I this an easy job?"

Very simple. Moss do a conversion kit.
Deborah Evans

Hi Dave

Have you been on the rolling road to confirm rich mix?

I bow to your knowledge Deborah you have probably dynoed more 1500s than we have. I can only go by my own experience on the rolling road when I recommend different needles, I must say I have never found standard needles rich enough even with only K&N filters fitted. I know the aams can be rich at full chat but give the richer mix for cruising. Sadly, like MGB tuning the needle just right is never in the list. On Bs the AAA can be too rich whilst the standards are way too weak. We quite often end up grinding the weaker needles to suit. I have lost count of how many needles I have ground after running my own rolling road for over 24 years!

We also try and ensure folk have fitted heat shields to keep those float chambers cool, the bane of 1500 owners.A dedicated cold air supply via the side of the rad works well too.

Peter
P Burgess

I absolutely agree Peter!


I also second your comment about the heat shield - this is ESSENTIAL on the Midget 1500 especially since the engine bay runs far hotter than does the Spitfire (which is another reason the motor is less reliable in the Midget than the Spitfire). Another good mod is to put vents in the lower aft edges of the front wings (see the photo' of our racer in my vehicle profile).
Deborah Evans

peter and deborah.
While we're talking about needles, perhaps you could recommend a good 'starting point' for my 1275.
using twin HS2 SUs, Piper HR270 cam, stage 2 head, LCB exhaust. - This was how it was when I took it off the road over ten years ago when it seemed to be running ok. Now I'm well into the restoration I figure I should at least try to get close to the right needle.


Graeme
graeme jackson

<< keep those float chambers cool >>

I coated the float bowl with vinyl(?) (Plasti-Dip) back when running a single HS4. Did it help? Don't know, but it sure didn't hurt. Vinyl has a lot less thermal conductivity than aluminium.

Richard Reeves

Hi Graeme

What needles are you running at the mo?

I usually try a pair of Ms and work my way up or down from there, if you have biased needles I will have to work out some choices.

We are, we think, beginning to detect a difference in fuelling requirements with the ethanol added to our pump fuel in the UK, especially with webers. I am, I feel, having to increase the fuelling to get the AFR correct.

Hi Richard

We have used ally backed tape to reflect heat in the same way.

Peter
P Burgess

Hi Peter.
The car was running on whatever the original needles were. As I say, it seemd to be running fine but I would imagine it would have been a bit lean.

graeme
graeme jackson

best get it onto a rolling road so it runs as sweetly as it can.

Peter
P Burgess

This thread was discussed between 25/05/2011 and 27/05/2011

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