High Idle Speed Mk3 Spitfire

[Maff]

Hi all. 

Long story short, took my spitfire to a local restoration place in Rothley to look at the temp gauge. He charged me £308 to replace the thermostat and give a general check up. 

Now my idle is at 1500 whereas it was below 1000 before I took it in. He claims the idle was 'all over the place' yet I can't recall this being the case. 

Is it easy to adjust the idle to the ideal speed? What is the ideal speed? 

Many thanks in advance! 

[johny]

Hi, Im not sure what work they carried out but that seems a lot of money!

The idle smoothness of any engine is dependant on quite a few factors so unless you're certain other adjustments such as tappets, carb balance etc are correct the best thing would be to check those first. There can also be air leaks or wear in the carburettors themselves which will also make it very difficult to get a smooth tick over however the good news is that the adjustment itself is very easy.

Our cars as standard are fitted with very simple carbs where the accelerator pedal just operates a butterfly valve in each carb to increase the amount of fuel/air mix going to the engine. The tickover setting is purely achieved by holding these butterfly valves open a little when the pedal has been released and this is done by a screw on each carb butterfly operating mechanism. They should be easy to see if you locate the accelerator cable (which must be slightly slack) and need to be undone a little and by the same amount on each carb while the engine is running and hot.

If you cant maintain a stable tick over at about 900rpm then you will need to look at some of the other factors that I mentioned earlier....

[Pete Lewis]

You have two carburettors each has a screw to  hold the throttles at any desired speed  adjust with a scredwriver , they should both be set the same , so they have a   balanced air flow just unscrew each equal amonts to bring the idle down to around 750 /800

And dont use this guy again.

There is also a screw which rides on a cam to speed up the idle when you use the choke  with choke fully in there must be a small gap between this screw and the small cam

Pete

[Ben Caswell]

Travelers were often fearful of being robbed by highwaymen and the Leicester Journal for  12 December 1775 reported that: ‘On Sunday night last the coach bound for London was stopped by a single highwayman near to the second milestone on the Harboro’ Road. He took from the passengers about £14; told them that necessity obliged him to do that or go to goal’.Was the garage owner a relative of a George Davenport by any chance!

[Maff]

Thanks for the useful advice, I'll have a look at the weekend. 

I'm well aware of being massively overcharged, it is painful but what can I do? He's an idiot and I live by the saying, what goes around comes around. 

[Clive]

Get along to your local Triumph meeting (TSSC/CT whatever) and get some advice on (a) how to sort the car and (b) who you can take it to in the future. Often people there who can sort anything and payment is peanuts.Or beer.

[Pete Lewis]

I would Put a workshop manual be it haynes autobooks or a club  reprint original on your christmas wish list

Pete

 

[Maff]

Cheers fellas. ?

[Anglefire]

Check the manifold gasket is not leaking too - mine was too high and wouldn't adjust down until I replaced the inlet manifold gasket with a proper payen one with compression rings around the inlets.

[Clive]

http://vitessesteve.co.uk/

Use that link to find free pdf's of a variety of workshop manuals. If the actual mk3 sit one isn't there, there will be the earlier herald/spit/vitesse one (combined) that will do 99% of what you need. And other manuals will have engine details.... Plus it is the genuine manuals with far fewer errors than some of the others!