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Spitfire Mk2 Jammed Throttle


Alisdair Lamplugh

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For a week or two my spitfire has had a sticking throttle in that from no revs it would not be smooth and jump a little. Yesterday the throttle pedal locked up and won’t move at all from the no revs position. I’ve had a little look at the mechanism but can’t see where there is any obstruction impeding the movement of the throttle pedal and wonder if this happens on other Mk 2 cars and what I need to do to remedy the situation. Thanks for any help.

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My daughters Mk2 Spit had rod and lever accelerator activation no cable except choke which is piano cable

The rod and lever system is a bugxxr when crossing speed humps so I’ve modified her car with a later pedal from a 1500 engine which connects using cables and I used a bike handbrake cable only issue it’s stainless and the nipples can’t be soldered on!

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It is a mk2 spit people there is no throtle cable it has push rods. First check that it isn't the carpet causing issues. It should be easy to see where it is catching though, watch the movement as someone tries to press it down and try pushing the rod attache to the carb linkage up. It might be worth disconnecting the linkage below the carbs to see if the fault is carb or pedal end. There is a bush where the rod passes through the sid of the bulkhead but failure here would make it flop around not stick

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Hi DanMi

Thanks for the advice; I have partly removed the carpet and underfelt from around the pedals but will remove it completely. When I operate the carburettor end it does move but I think I should disconnect this to see what this does. It went stiff suddenly and feels like something is now hitting the bulkhead and stopping the pedal from moving and Im hoping I will find a loose nut or pin that’s impeding.

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Hi DanMi

I followed your advice and found the rod attached to the carburettor connecting rail. I think this rod had become jammed and by moving it manually I managed to release the return spring and the accelerator pedal works again however it is still slightly sticking from the no revs position and I think this rod needs to be adjusted. I. See there is a screw in the top of the rod and a nut down near the bottom. 

I have the relevant Haynes manual and have tried unsuccessfully to find any mention of how to adjust this rod and think I should shorten the rod to get over its sticking perhaps by turning the screw. I wondered if you have ever adjusted the rod on your Mk 2.

At least I have got the car operating again and know how to un-jam it if it sticks again so thank you for your advice it has certainly helped.

kind regards

Alisdair

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the length of the rod between the carb linkage and the arm can be adjusted, it has a thread on both ends that the joints attach to. I would also check for play in the bush on the end of the pedal shaft, or rear of the arm under the bonnet. It is a small rubber bush that holds the throttle rod as it passes through the bodywork, if this is broken down the mechanism could catch

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Posted (edited)

Hi DanMi

The adjustable linkage on my car has an elbow shaped fitting at the top which had become loose. When posiitioned by the rod between the carbs and tightened up it allowed to mechanism to work properly in a sort of cam motion. Probably not the best description, anyhow with this done it works better than ever, although the bush through the bodywork does need replacing.

When I look at the Haynes manual the relevant diagram does not show this elbow shaped piece and the rod seems quite a bit longer. I wonder if this arrangement with the elbow fitting is specifically for the Mk 2?

Thanks for your help, its great to have car running well again.

 

IMG_1264.jpeg

Edited by Alisdair Lamplugh
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It looks the same as mine. MK3 was slightly different but essentially the same. The elbow shaped fitting operates the throttle and should be adjusted so they move the throttles exactly the same after balancing the carbs at idle

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