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General Spitfire messages

Afternoon all.

Sorry if this sounds a bit like some of my previous posts - it seems like every time I get enough information to progress with something I come up against another hurdle....

I know that this topic has been covered before, but I trawled the messageboards and nothing exactly the same as this has come to light.

I'm currently trying to sort out the running of my Mk IV Spit. The car is running K&N's and a sports exhaust, along with electronic ignition - all of which has been in place for some time and the car has previously run sweetly with these components in place (so it's not a case of the carb needles not matching the set-up etc), but since a top end rebuild a while back I've struggled to get the car running well (or indeed at all).

I've checked (and double checked) all the basics such as the plug gaps, the timing (static and running), the rotor arm, the compression, the spark, the fuel supply and the valve gaps, but I still can't get the car back to a drivable condition.

I was recently directed to a guide on tuning SU's which involves the lifting pins and the mixture settings along with the idle speed adjustment and a balancing tool to make sure that the two carbs are working together. I can get the car to a very sweet idle at around the right speed, with the carbs drawing in the same amount of air and the lifting pins having the right effect (so I'm told) of briefly increasing the engine speed then it remaining steady, but this all goes to pot as soon as you touch the throttle (mis-fire back through the carbs and drop in engine speed / stall).

I'm also concerned that it took far more adjustment of the mixture screws than I was expecting - the guide advised that I should back them off one flat at a time, but I must have backed them off at least 3 full turns (18 flats) from the recommended starting point before I saw any change.

I'm more than happy to invest in a professional tuner to come and have a look at it, but I don't want to shell out that sort of money if there is a chance that something is either attached incorrectly or broken which would prevent them from making any improvements.

Any suggestions greatly appreciated at this point! Summer is slipping away fast and I really want to get some miles under my belt this year!

"mis-fire back through the carbs" equals timing problems

Hi Neil,

I had a similar problem with my PI saloon. As soon as I had her running sweetly at idle, I apply some power and she'd cough and splutter and die off. After lots of fiddling and replacing, we diagnosed it was electrical. I checked all the earths and replaced the balast resistor, the coil, the points and the alternator and she now runs beautifully.

During the investigation I converted to and from 12V coil and back to 6V coil with and without Ballast resistors - now I'm back as it should be with the 6V coil and Ballast resistor.

Good luck with your investigation.

Pete

Confession time....

In between downpours (it rains more inside my garage than it does outside) I managed to get 15 minutes tinkering time and I found not one but two schoolboy errors that I'd made:

1) I hadn't tightened the dizzy clamp back up when adjusting the timing, so it was 'self adjusting' itself. This is far more common than you'd expect with me - I never seem to do ANYTHING back up again, which is why nothing ever works for long....

2) This is the really embarrasing one. I've just realised that I was setting the timing AFTER TDC rather than BEFORE. Obviously I hadn't bothered to even think about which way the crank was rotating!

It doesn't matter how easy you make things, there's always some fool who can cock it up, and that fool is usually me.

Running much better now - still needs some fettling, but moving in the right direction. It even started without a spray of Eazyee Start yesterday - things must be looking up! Just need to unseize the brakes now.

Sounds like you may have cracked it!
So it will be on the road for the errrrrr......Summer???

I'd like to think so, but there are a couple of jobs that I know need doing before it goes for an MOT (reverse lights aren't working which I think must be the switch on the gearbox, and the brakes are binding a bit), and funds are a bit tight at the moment - but fingers crossed it'll get there. I'm trying to run the engine every day to make sure that everything stays free and this has encouraged me to get it back on the road.

Still stockpiling my GT6 parts for an engine swap at some point - had the brake calipers shot blasted the other day and they came up like new.

The reverse light isn't part of the MoT, so don't worry about that. The brakes could well be lack of use. I often drive to an MoT with my foot lightly on the brakes as much as poss if the car has been stood for a while. Front or rear brakes?
Maybe see you (and russell) at the sussex meet 7 august?

I might be wrong but if a reversing light is fitted it has to work. Having said that it has never been MOT checked on any of my cars modern or classic.

Jon

I suspect the brakes will free off pretty easily - they weren't seized before I went on holiday (late June), so it's not a long term thing. Sadly I'm lacking my trolley jack at the moment as I had to lend it back to it's true owner (long term loan!) and I haven't got it back yet. Till then it's hard to tell whether it's the front or the back binding up - With the engine as ropey as it's been recently I haven't had enough bhp available to do anything other than crawl in and out of the garage, and you don't get much of a fell for the car at 3mph! If it's the fronts I might just put on the new discs and pads that I've got sitting in a cupboard somewhere - it'll need doing at some point.

Hope to get to the meet in August, especially if the weather is good, although I don't expect to have the spitfire MOT'd by then. I think the ticket on Russ's has expired too, but he he's waiting to sell another of his modern fleet to pay for the work needed.

Just had to fit a length of guttering INSIDE my garage to keep the car dry - given up on plugging the leaks now and just decided to work with them. Just counting myself lucky that I'm not in one of the flood affected areas.

I also guilty of that. Can't tell you the times I've set off in the Spit and rembered 200yards down the road that the wheel nuts need tightening, after some road side antics in the drizzel!

Touch wood nothings fallen off yet!

Jon

Only forgotten to tighten whell nuts once,, for about 50 yds.
Did drive all the way to Boston from Lincoln with the dipstick on the front chassis member, and once got about 12 miles with the radiator cap on the rocker cover.... Perhaps if I stop checking things that are not playing up and just keep driving the thing life'll get easier!!
Al M

Section : General

Tuning a Mk IV

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Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV

Tuning a Mk IV