HIF44 tuning

[Skittles]

Hello everyone,

I am new to this site and new as a mini owner. I have a 1986 Mini Mayfair and I just put a 1293 in it with an HIF44 carb. Have a little trouble getting it tuned properly. Have done research on it and have followed the instructions in the repair manual. Can you give me any other advice to accomplish this task.

[LarryLebel]

This is a wide open topic. What have you done so far? Is the piston damper oil reservoir full of oil. There is purpose made SU damper oil. I use 30W synthetic. If you can't get the mixture in the 'ball park' maybe you have the wrong needle. Is the carb original to the motor? There's 2 questions for you to answer but we need more information to be able to help.

[wantafaster1]

Good carb but mine gave trouble with the choke mechanism not sealing. I blocked it off completely. You will find it impossible to get it calibrated with that problem. And you need to know if the float is actually shutting off the fuel supply.

[ianh1968]

I am new to this site and new as a mini owner.

Welcome!

Have a little trouble getting it tuned properly.(HIF44)

This is a wide open topic

Yes - Exactly... This one is a bit difficult to comment on, at the moment.

Please describe the symptoms eg:
It won't run at all?
Is it bad idle?
Does it run "sort-of-ok", but has poor acceleration?
Does it feel "hesitant"?
Has it made the plugs go a "funny" colour?
Was it OK before, but now it isn't?
Was it previously set up using proper diagnostic equipment and/or a rolling road or chassis dyno?
Has it caused an extra two cylinders to sprout from the left hand side of the engine?

The more information you can provide, the more useful/sensible the replies here will be.
What is the rest of the engine spec?
What needle and spring does the carb currently have in it?

Ian

[Skittles]

To answer your questions:
The engine is new and did not come in the car.
It came with a 998.
Yes, there is oil in the dampener, it has Automatic Transmission fluid.
The carb has been rebuilt and the choke works fine.
The car running ok but it stumbles upon take off.

Trying to get it dialed in so I can start driving it on a regular base.

Thanks for the input

[ianh1968]

What is your location? You do not have it set in your profile...
The reason why I ask is because ambient temperature will
affect some of the choices made in setting an engine up.

A typical normal 20W/50 grade engine oil is a popular choice
in the UK. I don't know much about ATF, but a quick Google
says that it is typically 5W/20, which would possibly be too
thin. I am NOT an expert on fluid viscosity, so I stand to be
corrected by anyone who is...

A thinner oil will cause the piston rise much faster on
acceleration which can cause a temporary lean mixture.
This is the whole point of having the movement damped
and may be why your car "stumbles upon take off".

As it is very easy to do, my first suggestion would be to
try some thicker oil, unless you are somewhere really
cold. Please update your profile!

Good luck!

Ian

[LarryLebel]

What needle is in the carb?
Have you tried to adjust the mixture screw? In to richen out to lean.
What colour are the deposits on the spark plug electrodes?
Have you used the piston lifting pin to check the mixture?

Ianh1968 could be right. The damper system is there to enrichen the mixture on hard acceleration. If the damper oil is too thin it could be leaning out he says.

[Frogeye61]

According to the SU site, the damper oil is and always has been SAE20

http://sucarb.co.uk/dampers-caps-oil/damper-oil.html

[ianh1968]

According to the SU site, the damper oil is and always has been SAE20
http://sucarb.co.uk/dampers-caps-oil/damper-oil.html

... agreed, and so say some of the manuals as well.

All of my Haynes books have specified engine oil, and this is what I
have always used, as have many others. I've had engines dyno'd on
a few occasions and never had mixture issues due to too much damping.

Given the symptoms of the problem being discussed here, thicker
oil has got to be worth a try... If it turns out that it solves the problem,
we have a result - no more having to have "special" oil for the carb.
Everyone should have a spoonful of spare engine oil available!

If the thicker oil does not cure the problem, try the items in
LarryLebel's list.

Ian

[Skittles]

Ok first I would like to thank of everyone for there help.

I am located in El Paso, Tx. The temp right now ranges from 20 degrees F. at night to 60ish during the day.
I have just changed the oil in the dampener to a 10W30 engine oil. I have a stage on kit from Mini Sport, the needle is a BDP. I got a Gunson colortune and got it really close. It is running pretty good now. Waiting on a relay for the lights. Hopefully it will be here before Saturday. Have a chance to get her on a Dyno (rolling Road).

[ianh1968]

I am located in El Paso, Tx.

... quite high up at 3800ft - Be very wary of any "expert" needle
recommendations from others at totally different altitudes!
The differences may be small, maybe they won't. I am no expert,
I'm just making an observation here.

I have just changed the oil in the dampener to a 10W30 engine oil.

MY PERSONAL VIEW - Engine oil should for the 'A' Series should be 20W/50.
Many of the thinner modern oils do not have the "EP" protection levels for the gearbox.
I have also found that thinner oils tend to "burn away" much faster.

I have a stage on kit from Mini Sport, the needle is a BDP.

See comment above re altitude...
That needle might be perfect at about 500ft, in Lancashire, England...

I got a Gunson colortune and got it really close.

The colo{u}rtune is only good for setting the mixture at idle. The engine is also
at "no-load", so it does not confirm the mixture during driving conditions.
Use of these "tools" assumes that the needle in the engine is the correct one
for that specification and that only adjustment is required. If the needle was
correctly calibrated and the mixture was correct at idle, it should be correct
throughout the range...

Have a chance to get her on a Dyno (rolling Road).

Great! This is the way to go...
... and if you have a laptop, you might want to take this with you...
http://mk1-performance-conversions.co.u ... l_carb.htm

Good Luck!

Ian