24 replies to this topic

[Steve66]

How new/clean is your fuel tank?
Do you have any inline fuel filters before the carb?

I have two filters before the carb and yet the gunk had still found its way into the float bowl. I’m hoping this is my issue

I have just removed my tank due to the gunk and rust.

https://www.dropbox....d8623cveyt&dl=0

https://www.dropbox....rthdh4pnjg&dl=0

https://www.dropbox....nzb5l4zyte&dl=0

I have just had the carb in bits to check the float height and it was totally clean.  Tank is clean.   Thanks 

[Steve66]

 The BDL needle is the standard MG Metro needle. I 'think' my 1275 is an MG Metro engine, and has a BDL needle in the HIF44. It ran super rich when I bought it. I've backed it off 1 1/2 turns and it still runs rich. BER is a leaner needle, but it's difficult to tell what you need unless you can find out what your emissions are (mine was 8% at MOT, so way over 4.5% limit).

 

 Have you tried moving the dizzy clockwise/anti clockwise to see if the car runs better? The timing may be the issue. I'm certainly no expert though. 

No I haven’t.  Thanks for the idea I will try it 

[Steve66]

I think I am going to have to book into a rolling road setup

[timmy850]

I've recently installed my HIF44 and begun the tuning process 

 

The first step is always to check the ignition system is working properly:

What plugs are you using and what gap? Are the plugs black from being rich?

What coil are you using?

You've set the base timing to 8 degrees, have you checked the timing at 2000, 3000, 4000, 5000 rpm? 

Do you have vacuum advance? Is it working and how much advance is it giving?

 

Once the ignition system is sorted you can move onto the carb. Once the engine is hot at operating temp:

Set the idle mixture using the screw

Check the mixture at 2000, 3000, 4000, 5000 rpm and note this down. 

Leave the engine to idle for a few minutes and make sure the mixture is stable, isn't varying up and down too much or trending higher or lower over time

Bring the engine back to idle and then snap open the throttle and check the mixture. If you have the right damper and oil it should get richer when you snap the throttle. 

 

Getting the right settings, especially when running in are critical for the life of the engine

[croc7]

How new/clean is your fuel tank?
Do you have any inline fuel filters before the carb?

I have two filters before the carb and yet the gunk had still found its way into the float bowl. I’m hoping this is my issue

I have just removed my tank due to the gunk and rust.

https://www.dropbox....d8623cveyt&dl=0

https://www.dropbox....rthdh4pnjg&dl=0

https://www.dropbox....nzb5l4zyte&dl=0

Yikes!  I'd have a look at the fuel pump as well.

[Steve66]

I've recently installed my HIF44 and begun the tuning process 

 

The first step is always to check the ignition system is working properly:

What plugs are you using and what gap? Are the plugs black from being rich?

What coil are you using?

You've set the base timing to 8 degrees, have you checked the timing at 2000, 3000, 4000, 5000 rpm? 

Do you have vacuum advance? Is it working and how much advance is it giving?

 

Once the ignition system is sorted you can move onto the carb. Once the engine is hot at operating temp:

Set the idle mixture using the screw

Check the mixture at 2000, 3000, 4000, 5000 rpm and note this down. 

Leave the engine to idle for a few minutes and make sure the mixture is stable, isn't varying up and down too much or trending higher or lower over time

Bring the engine back to idle and then snap open the throttle and check the mixture. If you have the right damper and oil it should get richer when you snap the throttle. 

 

Getting the right settings, especially when running in are critical for the life of the engine

Thanks this is very helpful list of to do’s.  Problem is I can’t measure the mixture other than plug chop.   Rolling road coming up!

[Earwax]

All the usual suspects  Air / Fuel / Spark..  

 

A couple of quick checks to help diagnose 

 

Spray water/ WD 40 / etc around gasket faces/ carbie/manifold/head to see if you have air leaks ( listen to engine change)

 

Slightly loosen dizzy and advance until it sounds happy running at about 2000 - 3000 ( then check what that timing is..... compare with your preferred curve)

 

All of the above are good areas to look into : just look into them in an orderly manner  and just because it is new doesn't mean it is known good. ( thinking of condensors but leads, plugs etc Good luck

[pcs]

I've just fixed mine, running bad around 2000rpm. There was a bit of fluid(petrol?) in the vacuum tube between HIF44 and the distributor. Cleaned that and now running fine....

[Davidmt]

 

Too much static advance?

 

If it's running on, without really warming up, it must be close to detonation.

Hi it only runs on when hot

 

strangely it needs choke for cold start and then is instantly too rich with choke and only runs without choke

 

Have you checked and replaced the choke seals - mine was the same.  Would only start on choke but would instantly run rich as the choke could not be stopped.  No end of playing with the timing or fuel mixture would sort it.  Eventually removed the carb and had it refurbed includng new choke seals etc and once refitted it was back to running perfect.  I believe the seals are quite prone to perishing so if they have not been changed I would start there otherwise you could be wasting time with the fuel mixture and spark which may already be fine.

Edited by Davidmt, 23 June 2024 - 12:19 PM.

[Ethel]

The choke seals do like to fail if it's not been used in a while. Then there's ethanol as well now.

 

If you remove the dashpot you can blow down the float vent pipe & with a strategical placed finger, on the main jet, see if & when fuel emerges from the choke jet.