cliff.b

Hmm, I have just read that the 76 to 79 Spits had FZX1122 carbs and apart from any other differences these were fitted with ADN needles which appear to be leaner across the rev range than ABT's. ADN is grey line I have always found that if I set the mixture at home it is always much weaker if I stop in a layby and check the plugs during a run. Guess this might explain why 🤔

I'm considering refurbishing these carbs, maybe over the winter, but looking at parts I see there were various carbs fitted to the 1500 Spit and even 2 different types of waxstat jet are available. Does anyone know what the differences are?

In answer to all the above, I did some work on the linkages and refitted the jet so, by eye, the top of the jet was roughly the same height as the front carb. Adjusted further after a quick check with Colourtune then off for a road test which went well, to start with. I stopped & checked the plugs and rear ones were a bit weak, so lowered jet one flat. After this, the tickover was perfect and goes well with foot down, but running rough at slower speeds. Once again, pulling the choke out solved it do progressively richened the mixture and it got better, but not perfect. Now jet half a turn lower than the setting I started with and barely any difference to plug colour. I will work through all suggested here.

Hmm, took both jets out and the rear one does appear to be a couple of mm longer. Might be due to the waxstat "bodge" but the jets are solid in the carrier with no discernable movement. So how did this problem suddenly come about.? While looking at this I found the choke operating linkages are a bit sticky and I'm wondering if that jet has been stuck too low for ages and when I got the car running I adjusted around it. So if it suddenly freed up the jet would be too high and almost cut the fuel supply off to that carb at small throttle openings. Not sure if that is plausible but best I can come up with at the moment.

That is the one I gave loosed right off. I did the penny trick with the waxstats over 2 years ago so assumed the jet wouldn't move in the housing anymore.

Both jets

Spitfire been running really well for ages but today very rough, won't tick over and feels like misfiring until throttle opened wider & revs rise. All ok if choke pulled out a bit. Found tickover no worse if plug leads 3 or 4 removed so assume rear carb problem. After further investigation I noticed the jet on that carb is protruding 2 or 3 mm and obviously, operating the choke cures this. This explains the problem and winding it down several turns gets the car running ok but now externally, everything is considerably lower than the other carb. Struggling to work out what has happened 😟

Back in 1978 I put my first Spitfire, a Mk3, nose down into a roadside ditch and apparently went flying a considerable distance out of the open roof and ended up in a ploughed field. I say apparently because I don't remember it myself but there were witnesses. I'm in no hurry to repeat this.

Indeed. Perhaps having doubts about the collapsibility of my steering column will make me drive more carefully and therefore a "safety feature" lol

I don't have any "Allen head" bits that I can use with my torque wrench so used a ring spanner to give a bit of leverage on a regular Allen key. Tried not to over do it but presume if too tight it is the "collapsing in an accident" bit that might be compromised?

Ok, yes, that makes sense. The bolts were right but so was the grub screw at that point do I will check again. Incidentally, I have just tested and the steering feels more precise then before so although I wasn't aware of an issue it may have been a bit loose for some time. Anyway, thanks for the help 👍

I had about an inch play at the steering wheel rim but steered as normal when that was taken up. Wasn't like this a few days ago when I last drove her. Stopped and could see lower steering column not moving until flack taken up. Found locknut on safety clamp loose so tightened & play reduced but still there. At home tightened the grub screw and locknut and play now gone. Do you think this might be hiding another issue then?

Noticed some play when turning the steering wheel and on inspection, the locknut on the safety clamp is loose. Just wondering if the grub screw should be tightened up as much as possible before relocking or if there is a particular way to do it.

I know I have a Spitfire but have 185/70s on the rear and at 25psi, they seem to act like additional suspension, smoothing out the bumps and generally pretty comfortable. A small change to 27psi or above and the ride is far harsher.

As was the E-type, allegedly lol. Some say the car that was famously tested at 150mph may not have had a completely standard engine 🤔

Unfortunately he was a bit short on technical details and obviously a marketing man but well aware of the issues that the motoring press had raised for the earlier cars. Anyway, it added interest to a very pleasant lunchtime with an old friend who also brought his classic along and enhanced by a couple of those other Spitfires flying overhead on a perfect sunny day. Things don't get much better than this 👍

Just arrived in a pub at Duxford to meet a friend for lunch and while waiting in the car park, an old chap came over and said he organised one of the press launches for the MK3 Spitfire. Claims they fitted them with rear suspension off a Vitesse so the motoring press wouldn't do the sort of things they did with the earlier cars.

I did wonder if the engines got re-torqued after they were assembled in the factory.

I will take that as a vote for cold then 🥶

As I have just said on another thread, I will shortly be doing my re-torque and as advised, was planning on doing this with the engine warm. But this seems to be yet another of those things where there is a difference in opinion. So just wondered if anyone has anything definitive that clarifies this or if not, any compelling reasoning one way or the other? I presume if warm the studs would expand, thereby lowering the clamping pressure, but wouldn't the specified torque take account of this?

Ah, I missed this post. Makes sense.

Thanks. See he is doing it with the engine cold.

Did he explain why he backed them off first?

Interested that you suggest not loosening nuts during a head re-torque. I'm almost at the mileage for doing mine after my recent head gasket replacement and most advice seemed to be to warm the engine, slightly loosen each nut then re-torque before moving on to the next one. Not sure what the reason for the loosening was though.

Does the odometer/trip read distance correctly. If so then that suggests it is the Speedo mechanism at fault and everything else is ok. As is the case with my Spitfire which also under reads speed.