SLeonard

Looking for some sage guidance! Our Spitfire mkIV (with 1500 engine swap) has started to get an occasional issue with the clutch. This week, 15 miles into a drive, the clutch pedal went stiff and almost felt “rough” to press but still had full travel. On switching the engine off the clutch went back to normal and light. So, we drove home as didn’t want to chance it. On the way back it again went heavy in traffic for a moment then as suddenly went back to normal. Clutch fluid level is good and fluid looks clean. Not sure how old as it would've been the PO. Any ideas what might cause this before I started tearing bigger stuff apart? Thanks everyone!!

They are NGK BP6ES. So, pretty sure the fuel mix is right (colortune blue flame and idle stable when lifting the carb piston 1mm. The car runs under light load and at even speed, but as soon as you go open throttle it hesitates and stutters and doesn’t go. Sometimes this clears and it behaves for a few streets, then it comes back again. 2 days of tuning carbs I’m sure its good, and spark plugs are cleaning up and starting to tan now its been run a bit. previous owner ran E10 and lad has just put 97ron in. Not sure why this would matter, unless its messed up the timing.

Thanks @Pete Lewis We will pull the plugs soon as we are replacing. Any suggestions which ones and we’ll happily go with those. The existing plugs need binning anyway as they are pretty choked and obviously one is pretty wet. We’re fixing the oil issue and switching the plugs at the same time. Meantime, the car starts on the button and is smooth so I’m happy the issues are resolved.

Plugs and gaps are good. Cleaned and rebalanced the carbs and fixed the throttle linkage sticking. Car is running smooth with good power through the range and idling smooth at ~600 rpm. Might raise the idle slightly as get the charge light especially when fan is on, but its happy and voltage is 14V. Still pulls oil but nowhere as bad at the moment. We’re going to overhaul the valves and head in the next few weeks and fix various engine leaks. Thanks to everyone for their help! We have a happy 18yr old who now knows how to balance carbs, and a chuffed 45yr old whose dusted off some nearly forgotten skills. Here’s to some happy motoring!!

@JohnDIt was but not anymore 😂. Spark plug gaps were too large so I’ve reduced them to 0.025, and its been rough ever since, with uneven idle and drove terribly. Spark plug 3 is really wet with oil so its getting in somewhere. I’m going to recheck leads and plugs tomorrow but I also suspect oil is passing the valves on cylinder 3

@Josef I’ve realised it has Smiths aftermarket dials, so I expect a previous owner has fitted lights to the dash. Orange is the ignition warning/ charging light. Blue is main beam. Red I would imagine is the oil pressure. Not sure if that should also light on ignition on as a test, but never does.

So, compression test done, cylinder 3 spark plug was wet with oil, explaining the smoke. However, compression test results seemed okay to me? cyl reading1 reading 2 1 161 160 2 175 175 3 171 170 Wet Spark plug 4 166 165

Sage advice again @Pete Lewis and appreciated. I’ll check the little things and see how it goes. Exhaust is black with soot. For the effort and peace of mind I will pressure test tomorrow as well as its a fairly simple test.

Thanks @Steve P! Great to have a recommendation. We’re going to speak with Maynards. I’ve checked and turning anticlockwise raises the jet making it leaner. I should trust my ear as the car is running better, smoother and even, and the strong petrol smell has gone. The throttle linkage is catching as well which looks to account for the high revs after a little use. The springs seem quite slack so may tension slightly and lubricate with silicon spray. Unfortunately its smoking now (blue smoke though, not black). I’m doing a compression test tomorrow as I suspect a worn ring or valve seal. Maynards may come in useful! Just seems odd to just start smoking now although the car is new to us and we have overhauled the ignition, charging, tightened belts and are using it more. I wonder if its just highlighted some wear elsewhere.

Hi @johny . Not sure if I have an earlier mkiv dash, or it changed, but I have 1 orange light towards the passenger side of the car/ dash and 1 red light to the direct left of the main dials in the dash (never ever comes on even on ignition). No lights in the speedo.

Hang on @Steve P. Winding the jet adjusting nut anticlockwise makes it richer? I did get confused by the Haynes manual that states up for leaner, down for richer, so I screwed anticlockwise which is “up” the thread? You’re local then? Sounds like Maynards might be a good shout as engine needs a thorough going over too.

Hi all. Bit of an update. Wound the idle right down to just under 1000rpm and the had to turn the jet adjustment 3 full turns anticlockwise which I think is leaner. Car idles smoothly and is more driveable. It feels like it has less power, but smoother and less frantic. However. The bad bit. Car is now blowing blue smoke especially on initial throttle and acceleration and the orange light flickers on on idle. I can’t see how this has anything to do with changing the fuel/ air mix but maybe someone could enlighten me, or just plain bad luck?

Looks like a previous owner has already installed fixed jets (or they predate waxstats)as I can see a red end under each carb, so I’m guessing we will just need to balance them. I’ll test for air leaks too. Car runs at 1000rpm on cold start with choke but rises to 1500-1800 rpm quite quickly as it warms, with choke off. I’m going to check timing and then have a go at rebalancing the carbs tomorrow.

@JohnD Thanks for the comment. I have experience with classic Mustangs, although currently I have a newer 2009 GT500 with a built engine and larger blower. My lad though is looking for advice for reliability, not performance. At 18 any modification to drastically increase performance would need declaring and probably be too costly for his insurance. He is looking to drive the car much more regularly than it has done for years and use it. Happy for people to say use the stock fuel pumps etc, if they are reliable. Likewise the carbs and ignition, but have made the (maybe wild) assumption that there would be more reliable options to SU’s and the original dizzy/ points. This thread is already proving valuable and I am very appreciative, thank you!

Thanks. Thats some great advice and appreciated. I’ll look at making the changes this weekend. Pretty sure the bulb lights with ignition on but will check. Ordered an alternator anyway and will rebuild the old one with my son. It’s his car and great getting an 18yr old learning these skills! I’m also wondering if there’s a leak to the manifold adding air to the mixture when it warms up, so I’ll order some gaskets. Okay, so we’ll rebuild the carbs, find 4 x 1p coins (2 for each) and some gaskets! Wish us luck! Thanks again @Pete Lewis. This is a great introduction to the group and its value. I hope we can give back soon! Simon.