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Spark plug colour


alan.gilbert_6384
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2 hours ago, Pete Lewis said:

well the electrode seems clear but thee base looks sooty  had this been running on choke   that can take 10mile of hot driving to clear it 

Pete

Hi Pete, oh, maybe I need a longer run after its warmed up, this was only about 5 miles.  I have done the carb lift pin check 1 to 2 mm (approx) and no change in RPM, then all the way up and it stalls (i believe this is correct).  Checked with the colour tune, and balance air meter all looks good.  Will try again, if it stops raining before Christmas ;)

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no point in a full lift it will just stall 

all sounds to be pretty much  OK

was the pin lift with air cleaners on  as taking them off gives very false results 

i see no logic in the books that suggest a lift with a screwdriver and cleaners removed as the 

intake vacuum is vastly different between being on or off    chalk and cheese results 

it must always be in  a as on  road running condition 

sorry in cold dismal mood   ha !

 

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good  were the needles changed from std to  get  the mixture right with KNs  as they would normally weaken from std as there is less 

depression to pull fuel from the jet  so with a std needle you probably have to set it richer to actually run reasonable ?

just some ramblings  

Pete

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Alan, there is a windows program called WinSu which allows you to enter the cars details and any modifications and it will then select some suitable needles and springs - obviously keeping everything standard will give you factory - which are either ADT or ABT depending on late or early 1500. I think early is the Mk4 and late the 1500.

If you take the needles out of the carb - the reference is stamped into the end of the needle. On the attached the red line is "standard" for my car and the other 4 lines the next suggested needles for the spec of my car - not a lot of difference!

image.thumb.png.3aa9ebc7b363a6eb3aad91262b8522cf.png

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early are ABT then late ADN std filters

KN and tubular manifold  AAR   

https://www.canleyclassics.com/?diagram=triumph-spitfire-mkiv/1500-carburettor-details-twin-carb-engine&ptno=AAR

https://www.canleyclassics.com/?diagram=triumph-spitfire-mkiv/1500-carburettor-details-twin-carb-engine&ptno=ABT

https://www.canleyclassics.com/?diagram=triumph-spitfire-mkiv/1500-carburettor-details-twin-carb-engine&ptno=ADN

when undoing the needle grub screw the whole bias block and its small spring will come out  just take care and replace in the same place 

so the screw locates in the slot and its flush with the base of the air piston 

pete

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10 hours ago, Pete Lewis said:

early are ABT then late ADN std filters

KN and tubular manifold  AAR   

https://www.canleyclassics.com/?diagram=triumph-spitfire-mkiv/1500-carburettor-details-twin-carb-engine&ptno=AAR

https://www.canleyclassics.com/?diagram=triumph-spitfire-mkiv/1500-carburettor-details-twin-carb-engine&ptno=ABT

https://www.canleyclassics.com/?diagram=triumph-spitfire-mkiv/1500-carburettor-details-twin-carb-engine&ptno=ADN

when undoing the needle grub screw the whole bias block and its small spring will come out  just take care and replace in the same place 

so the screw locates in the slot and its flush with the base of the air piston 

pete

Interesting - I went on the MOSS site for the references which are different - so the graph revised with ABT, ADN AAR and ABS which is what was suggested for my Spit

 

image.thumb.png.10690060559ce89d61f42f867d6154b5.png

 

And yes, that is a tubular exhaust.

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