48 replies to this topic

[mk1leg]

sorry to ask but have you got the leads and firing order correct......1-3-4-2 in anticlockwise order with no1 lead at approx 2oclock

[Bradshaw-s]

Hey guys,

 

Question:

 

1. Dave (Kernow) suggested that the timing may be retarded - I turned the distributor both clockwise & anti clockwise 90-180 degrees in both directions & did not seem to make any difference BUT the distributor is brand-new 59D (Lucas 41907) - is this the correct type for this head as it has just been replaced (CAM4810 Leaded) ?

Is this 100% an air leak issue?

 

2. If the butterfly did not close tightly with a tiny gap at the bottom (as Earwax suggested), would this cause the engine not to run (off choke) even when fully up to temp through a heat cycle? I do have a very, very small gap at the bottom of the butterfly.

 

3. I can be as sure of 99% that no air leaks through the mated surfaces as I have been meticulous with re-assembly using the gaskets & liquid gaskets, is there any other ways for the carburettor body to leak air in?...bearing in mind that a new service kit has been installed which includes the rubber spindle seals etc..

There are no other obvious hairline cracks in the body as I have carefully inspected & cleaned the body.

 

Yes the firing order is correct, along with the static timing & valve clearances - re-checked/set this on friday just to eliminate out of the equation - set to between 5-8 BTDC.

So because of the air leak suggestion - I again stripped the inlet & exhaust manifold off - ensured that the shoulders of the inlet & exhaust manifolds are the same thickness to eliminate this possibility. I had a new inlet/exhaust gasket which I installed - again cleaned all mating surfaces & used liquid gasket as a backup - 100% no air is entering through this area!

 

The needle is an AAU - recommended for stage one kit -Red spring fitted & engine oil used - have SU oil on order - this carb was purchased as seen so I serviced it & modified it as just stated.

 

Si

Edited by Bradshaw-s, 05 October 2014 - 03:46 PM.

[Earwax]

Hi

 

very frustrating for you.  If you had the car running and turned the dizzy, you should have made a difference.... it should have gotten better or worse or died etc somewhere along the movement cycle... if it didn't do anything ??? i would go back to the prior suggestion to get a known good dizzy and try that... You have been very thorough with the fuel possibilities , so now perhaps we just have to try the electricals again.... it does sound as if it is retarded as suggested above..

[KernowCooper]

As earwax has said by that amount of rotation on the distributor you should have see a big increase in revs or loss and stall ? can you turn yours 180degs ? I cant ? if the car will start and run and you rotate the distributor clockwise it should increase the revs a lot, if the car wont start and you do the above then it should kick back while cranking.

 

Can you go back and bring the No 1 cylinder to tdc with both valves closed and recheck you static advance again, rotor pointing to 1 oclock and place no 1 lead in the cap at that point and counter clockwise 3-4-2 and confirm

Edited by KernowCooper, 05 October 2014 - 11:58 PM.

[Bradshaw-s]

I have 2 dizzys spare - one from the recon engine (before I bought new) & one from the existing old engine - which was a non A+ engine.

Will give them a try today & reset & double check the static timing as Dave suggested - will report back later today.

Thanks guys!

[Bradshaw-s]

Groan!!!....

OK have changed the dizzy over to both the spare dizzys I have - one a known working one from the previous engine I took out - the other which came from the "Recon" engine I bought & have had all the trouble with )

Put new points & condenser in the old ones also...

 

Anyway I double checked the static timing & set at between 5-8 BTDC - using test lamp - rotor arm at 1 o'clock etc... unfortunately the problem did not resolve itself - but I did get response with engine revs when turning the dizzy as far clockwise & anti-clockwise as possible which I did not with the brand-new 59D I had purchased...

 

Is this progress Maybe????

When playing with the carb again...I managed to get the engine to idle without the choke....yay!...BUT only by blowing air through pipe A??!!

I took off the suction chamber off to see what this meant...when blowing through pipe A, petrol was being forced up the jet & air was passing through the overflow - but what should happen is the lower vacuum pressure within the carb would cause the higher atmospheric pressure within the reservoir to force the fuel up?

 

Am I correct in assuming that this proves that there is insufficient differential pressure to allow the fuel to be forced up the jet?...which then proves an air leak somewhere as Kernow has always stated...but where from...???!!

Its 100% sure its not through the mated surfaces - with new gaskets & liquid gasket this can now be eliminated - where else can I check??

 

Can you guys explain to me the process of pipes A & B on this carb? - I realise its for economy originally, but how does it work?

Shall I just get a replacement carb?....wife is not happy with the progress & I am desperate now - just need to know its the carb for sure!!

 

Si

Attached Files

•  CarbQuery.jpg   42.02K   33 downloads

Edited by Bradshaw-s, 06 October 2014 - 04:22 PM.

[silve1999]

Im no expert so dont listen to me but it seems that Essentially you were adding more air to the mixture, I guess leaning it out will make it run. Could it just a be very very rich mixture? :)

Edited by silve1999, 06 October 2014 - 01:08 PM.

[Bradshaw-s]

By blowing through pipe A I was increasing the air pressure in the fuel reservoir I think as air was also coming through the overflow, this in turn forced it up the jet - this indicates to me that there was insufficient vacuum in the carb to create the pressure differential needed to allow the fuel into the carb.

 

Adjusting the mixture only really effected the running at either of the extremes ...very lean or very rich.....I just need confirmation that this is the case )

Edited by Bradshaw-s, 06 October 2014 - 01:21 PM.

[silve1999]

Ignore me i am looking at a bad diagram

Edited by silve1999, 06 October 2014 - 01:24 PM.

[Bradshaw-s]

)...hey any inputs welcome - )

[silve1999]

I found this similar problem ¬

http://www.theminifo...-after-fitment/

[gazza82]

I found this in my collection of downloaded images .. this is a HIF44 though.

 

Edited by gazza82, 06 October 2014 - 02:59 PM.

[silve1999]

also found this on a minors owners group

 

 mbimage.jpg   26.07K   23 downloads

[Bradshaw-s]

Hi Guys,

Thanks for your replies - I have already sussed what pipes are which in an earlier thread a few months ago with the help of Kernow & Tommyboy - had blanked the correct ones as stated - but my problem is related to not idling without the choke being at least half way out - 

Still feel I have an issue with an air leak from elsewhere - not the pipes or mated surfaces - maybe through the linkages - at a loss!!

[Bradshaw-s]

Groan!!!....

OK have changed the dizzy over to both the spare dizzys I have - one a known working one from the previous engine I took out - the other which came from the "Recon" engine I bought & have had all the trouble with  )

Put new points & condenser in the old ones also...

 

Anyway I double checked the static timing & set at between 5-8 BTDC - using test lamp - rotor arm at 1 o'clock etc... unfortunately the problem did not resolve itself - but I did get response with engine revs when turning the dizzy as far clockwise & anti-clockwise as possible which I did not with the brand-new 59D I had purchased...

 

Is this progress Maybe????

When playing with the carb again...I managed to get the engine to idle without the choke....yay!...BUT only by blowing air through pipe A??!!

I took off the suction chamber off to see what this meant...when blowing through pipe A, petrol was being forced up the jet & air was passing through the overflow - but what should happen is the lower vacuum pressure within the carb would cause the higher atmospheric pressure within the reservoir to force the fuel up?

 

Am I correct in assuming that this proves that there is insufficient differential pressure to allow the fuel to be forced up the jet?...which then proves an air leak somewhere as Kernow has always stated...but where from...???!!

Its 100% sure its not through the mated surfaces - with new gaskets & liquid gasket this can now be eliminated - where else can I check??

 

Can you guys explain to me the process of pipes A & B on this carb? - I realise its for economy originally, but how does it work?

Shall I just get a replacement carb?....wife is not happy with the progress & I am desperate now - just need to know its the carb for sure!!

 

Si

 

Attached Files

•  CarbQuery.jpg   42.02K   13 downloads