Spitfire 1500 will not run without choke :(

[alan.gilbert_6384]

Hi All,

Been having some troubles with my spitfire 1500.  Put it away a few weeks ago and all was fine except a timing issue.  This keep changing for no reason (using a strobe to set it), so talked to power spark and after some advice on this forum concluded that my 45D4 was not as should be for electronic ignition module (the actuator ring could sit too low on the shaft leaving a significant gap between it, and the rotor arm).  It used to run ok, but not anymore.  Ordered a new dizzy from Powerspark (points type as I already have the electric unit).  So came to fit it, only to find that the relatively new solenoid (4 months old) was now stuck in, aghaaaaa.  Replaced this with the old solenoid (keep this as spare just in case) and all worked.  Came to fit the new dizzy, checked the offset dissy drive was in the correct place and fitted the points dizzy.  Set the timing static for now using a test lamp, and started her up, all well.  As the car warms up putting the choke in, then it all stops, the darn thing will not run without choke when warm.  Has any one got any ideas ?????????  Have I now got a third fault with the carbs ?????  feeling very unlucky at the moment

[Pete Lewis]

are you not just a bit retarded( dont take that as a personel reference ) and you old idle setting is just now too slow 

i would advance it and set it by ear  turn the dizzy to the get the fastest idle and back it off a small amount ( you dont want it at "best")

if this brings the idle up it then your static /bulb setting is either not enough advance or  it was too far advanced before and the idle screws both need a turn 

to get that right with the correct timing 

Pete

[alan.gilbert_6384]

Hi Pete,

Thanks, I set the static according to the book, ie lamp on at 24' and then turn engine to 10' then turn dizzy until light goes out.  thing is as soon as it starts to get warm if you start to push the choke in it just dies, no matter how much accelerator pedal you give it

[johny]

Its sounds like the mixture is very weak for some reason so runs ok on choke but then becomes unsustainable when thats pushed in. Its going to be either too much air from somewhere or too little fuel....

[alan.gilbert_6384]

Hi Thanks Johny,

I tried the old dizzy still with the electronic unit (the dizzy was marked on its rotation before I removed before this issue arose, so i knew were to set it) exactly the same issue, soon as it gets warm, try getting the coke in and it just dies, no matter what you do with the throttle.

[johny]

Hey I would keep off the coke, thats not going to help😂 But something must have changed on the carbs, stuck piston, mixture adjustment or air leak? 

[Pete Lewis]

2 hours ago, alan.gilbert_6384 said:

10' then turn dizzy until light goes out

not sure where that comes from you turn the crank pointer to where you want it   eg 10 deg and turn the dizzy till the light just comes on ie the instant the points open  never till the light goes out ,          

(or leccy unit triggers is the  just the same as points , )

[johny]

Depends how youre set up Pete, series or parallel. I do it ignition off and use a supply from the battery through a bulb and connected to the points supply wire then the bulb is illuminated to start with until you get to 10º BTDC and the points open so the light goes out....  

[Pete Lewis]

 ok  but me always small bulb   ignition  on  and  connect bulb between coil dizzy line and  earth  

bulb lights as soon as the points or leccy opens .

Pete

[alan.gilbert_6384]

Hi Johny,

Will begin the carb checks today, minus the coke

HI Pete, I set them according to manual, guess there's more than one way to skin the cat

[Anglefire]

Trouble is modern fuels are different today with different burn characteristics so timing to the book is not always the best way. 
 

[Pete Lewis]

as it was running fine before you swapped the dizzy insides it is most unlikely to be any mixture problem

sorry i will stick with olds school  timing methods they have worked fine for 60 years with me 

pete

[Mjit]

If the engine needs choke then, as jonny said it means the mixture is weak.

My first stop would be to remove the carb/rocker breather hoses and give them a very good inspection off the car.  Had a time when my Spitfire would drive fine for miles then, usually after being given some beans, need choke to run.  Turns out the extra RPM would open up a (while fitted) invisible split in one of the breather hoses, so dumping extra fresh air in to the mix.  Was right on the jubliee clip so impossible to see till I remove the pipes from the car.

At least a cheap fix if it's that!

[alan.gilbert_6384]

Cheers Mjit, I am planning on more investigation tomorrow, and will look carefully at the hoses.

[Mathew]

My 1500 twice had a problem of not running except at 3000 rpm.

First was waxstat leaning the mixture off, the second was when the blanking plug for the servo take off on the manifold unscrewed! Luckily it was on the manifold, stoped at the big roundabout at st.albans .

[alan.gilbert_6384]

Hi every one,

Update on the issue, looking at the manual it has this,

[alan.gilbert_6384]

So then dismantled the carbs to find this,

[Pete Lewis]

so the jet is too high and the needle too low   how did it run before ...with difficulty  i would think  ???

you  should feel a big difference with them set to the basics 

Pete

 

[alan.gilbert_6384]

As you can see the root cause is a bloody loose screw (they do say that dogs look like their owners temperament and all, wonder if its the same with triumphs ?)  So set it back up again level with bottom of the piston.  Now the manual says adjust the jet to the top of the bridge, but it does not say exactly which part of the bridge, as the jet bearing is also present and just slightly lower than the aluminium area around it.  So I lifted the jet until I could just feel the piston to move and marked the flat of the nut.  Then down two full turns, and then (when engine is nice and warm) back up each one one flat at a time until the engine just starts to lower rpm and then back one flat at a time until back to same rpm.  I then checked with the colour tune (last used in 1981/2, never throw things away;) to make sure all was well as well as using two balance measures.  The Malcometer and the more normal flow meter.  All now good, checked after extensive run and the plugs look good as well, yippee 

[alan.gilbert_6384]

Also decided to oil the trunions as the sun was out.