21 replies to this topic

[PeterG]

I have a HIF44 on a 1380. I rebuilt the HIF44 with the full rebuild kit from SU (Burlem Industries)

 

Always consistent. 7 turns to start cold. One turn to start hot.

[cal844]

I have a HIF44 on a 1380. I rebuilt the HIF44 with the full rebuild kit from SU (Burlem Industries)

Always consistent. 7 turns to start cold. One turn to start hot.

My minis behave similarly, the mechanical fuel pump needs to lift the fuel from the input into the carb

Edited by cal844, 09 August 2022 - 07:47 PM.

[Timmyquick]

It could indeed be a vacuum leak somewhere. What are the common places where the leak could be and what is the easiest way to find it?

Should I test cold starting with the vacuum advance disconnected?

Yeah, quick easy try to eliminate a dizzy vacuum leak, but at the same time might be advancing your ignition timing a bit on idle.

I was recently have similar issue and I had vacuum leak on the brake servo. I eliminated that by plugging the vacuum plug on inlet manifold (temporary for testing) Though my idle issue was a few issues together. Vacuum leak on servo, tiny split dizzy vacuum hose and a lean mixture on idle.

I also checked my valve clearances. Had to just keep eliminating stuff.

[Nielsj1996]

I have tried with the dizzy vacuum line disconnected but this does not give result I hoped-for.

I have connected a vacuum gauge which indicates between 17 and 19 inches but the needle does vibrate quite a bit. But if I turn the mixture richer the needle stops vibrating and remains nice and steady but then the engine is too rich.
As far as I can find, the vibrating needle means that the valve guides are too loose. I don't know if difficult starting and fluctuating idle are symptoms of this. And how would making the engine richer remedy this?

The car doesn't use a drop of oil either.
(Here is a video of the vacuum gauge, but the needle vibrates so fast that the video frame rate does not keep up. So imagine that the needle vibrates…  https://youtube.com/...w?feature=share)

Edited by Nielsj1996, 10 August 2022 - 07:37 AM.

[sonscar]

Vacuum needle vibrating at idle is an indicator of leaking valves.Just an old mans experience,Steve..
Rich mixtures light off easier as the fuel molecules are closer together.I was always taught that adjusting the carb was NEVER the answer(unless someone previously thought it was)

Edited by sonscar, 10 August 2022 - 03:34 PM.

[Timmyquick]

Unless you can do a leak down test, that's a bit harder to eliminate unfortunately without spending some wonga.

[Nielsj1996]

The idle problem has always been there. Possibly the previous owner also tried to solve it with the mixture.

 

I will ask my local mini specialist if they have another vacuum gauge and a leakdown tester. Just to be sure.

 

If the valve guides are the problem is it possible to use a different needle to make the car idle richer to temporarily solve the idle problem?  

and which needle should this be? (The current one is a BFY needle)

I know this is not the right solution but I don't use the mini much and would like to keep driving and overhaul the engine in a few years instead of doing things twice.