1275cc with HS4 running problems

[Piston broke]

Hi all.
I have just purchased a NEW HS4 marina 1300 carb from Burlen, for my minor which runs a marina 1275cc engine.
My local experts are having issues setting it up to run nicely. They cannot seem to get it to idle well on cold start and there are flat spots once running- and I'm having to floor it to get through them. Also seems to be chucking out some smoke at rear on occasions.

The oddities of the vehicle are- 3 branch manifold from Birmingham. Bigger bore exhaust also from Birmingham but only ONE silencer on it, and a K&N air filter.

I'm thinking it needs a better needle in the carb to cope... Anyone running similar or have any thoughts on this that might help her run smoothly ?! What is the best needle, currently it has a standard for the carb fitted.... Whatever's that is...!

Thanks.

[bmcecosse]

What needle is in it right now? Try EP90 in the dashpot.

[Piston broke]

It's got an AAQ needle in it at present.

Ep90? Really? Isn't that stuff really flammable?.

[bmcecosse]

Far from it.. The 'starting point' for the 1.5" carb is the AAA needle -quite a bit richer. But may not give best economy. Try the EP90 first...

[philthehill]

Whilst the HS4 as fitted to the Marina are similar there is a profusion of needles fitted.
What tag number is fitted to the carb? For example - carb with tag number AUD524 has the AAQ needle fitted.
The exhaust manifold should not make much if any difference to the needle required but the K&N filter may - but going right back to basics do you know what is the year of your 1275cc engine - and importantly what is the tag number on your carb.
Get those two right and that will be a good start line.
Here is a list of 1275cc Marina carbs with year, tag number and needle which will be your base line:-
71/72..................AUD354................AAQ
71/72..................AUD426................AAQ
72 >....................AUD541................AAZ
72 >....................AUD542................AAZ
75/76..................AUD670................ADG
75/76..................FZX1071...............ADG
76/80..................FZX1189...............ADG
76/80..................FZX1191...............ADG

[Piston broke]

The carb is AUD 354 so needle should be correct, I will try the alternative oil and may replace the air filter with something else like a standard morris or mg one. Or maybe I will give air filter a good clean and oil....thanks for the advice...

[bmcecosse]

The 3 needles listed above are insignificantly different to each other.... If the heavier oil doesn't help - get an AAA - or some find the AAU suits well. The AAU is initially the same as the first 3 then richens up as the flow rises. The AAA is richer again and from an earlier flow. The AAU is likely to give better economy, but perhaps with less power. Although it is a new carb - just check the piston is rising and falling freely. has the timing been 'optimised' - to just not quite pinking ? And is the vacuum advance connected? And the breather pipe ? What air filter is fitted? Not a daft 'pancake' I hope !

[Piston broke]

not sure what would be defined as pancake... It's far from flat but may be overkill. The vac advance is not present on this carb which I find odd... Could that be an issue? I'm assured from Burlen its a proper marina pattern carb and I thought they all had vac advance. Engine is not a plus. Standard 1275 marina type. No fancy tweaks.

It actually ran better when it was running lean.

Any tips to get oil out of dash pot without disconnecting the lot and tipping upside down?

[Declan_Burns]

Use a syringe and a piece of tubing to suck it out.
Regards
Declan

[bmcecosse]

Vacuum advance is very essential for good running, and economy. It both 'brightens' the engine response to the throttle - and improves economy... Leyland left it off on some engines to help eliminate 'main bearing rumble' - although how it was supposed to do that is well beyond me..... Try running without air filter..is it better, or worse..

[Piston broke]

I will be testing the theories (all except needle changes) on Saturday and will feed back. Cars an everyday runner.

[philthehill]

This is the correct type of air cleaner that you need to fit to your Marina engine Minor.
Ditch the K&N and as you already have the correct needle for the carb all should be well in that area.[frame][/frame]

Sorry about the size of the printing but could not get it larger without distortion.
The part Number for the air cleaner and silencer assy is 12G3590 (Plastic) & 12G2813 (metal).

The distributer Pt No: 12G4182 (high compression engine) or Pt No: 12H4853 (low compression engine) fitted to the Marina 1275cc engine should have the vacuum advance fitted and be connected/in use.
What is the number of the distributer (can be found on the side of the distributer).
It should be either 41372 (high compression engine) or 41234 (low compression engine)
The type of distributer is 23D4 (high compression engine) or 25D4 (low compression engine).
The illustration and part numbers are taken from a genuine BL Marina parts list Pt No: AKM 0034.

[Piston broke]

Thanks. If I can't rectify with tuning I will ditch the air filter. Have had same set up working well in the past... And the air filter did aid performance. Also.... Can't seem to find any marina air filters on eBay....

[liammonty]

The non-Marina exhaust is likely to be making a difference to the carb requirements - hence the standard Marina setup won't be quite right. Changing exhausts (especially manifolds) has, in my experience, made a huge difference to the running of the car. The £80 I spent getting my car set up on a rolling road was the best £80 I could have spent with its variety of non-standard parts. You need to find a place that is good with A-Series engines (especially SUs) though, as many places don't know what they're doing.

Many will say it's not necessary to use a rolling road to set it up a modified engine, but unless you have near unlimited time on your hands, plus a CO meter to be able to monitor mixture throughout the range of throttle openings and revs etc, not to mention the expertise, it really is. Just make sure that everything else (valves, mixture, breathers and so on) are set up perfectly before going for a session.

[bmcecosse]

I agree - but most places are only interested in producing a 'graph' of the power, so you can earn Pub Points with it on Saturday night. This is hardly a hugely modified engine - I'm sure the AAU will be fine.

[Piston broke]

Right...

The thicker oil made no difference.

Running without the air filter made negligible difference.

Adding two flats to riches the mixture didn't do loads either.

I did clean and treat the K&N to make sure it wasn't dry or dirty.

Will check out the distributor next to ensure its the right type.....

[bmcecosse]

Order an AAU needle.........

[Piston broke]

Dizzy is a 41270 B. Is that bad?!![frame][/frame]

[bmcecosse]

I'm a little bit surprised to see such an early dizzy on a Marina engine - but as long as you connect the vacuum advance (and check it's working') it should be ok.

[Piston broke]

It was one I had in shed!

Re the vac advance, the carb doesn't have facilities for this....