foshi Posted July 30, 2023 Report Share Posted July 30, 2023 strange one reversed spitfire up onto ramps to do a bit of welding shot up no problem. following 1 week started it yesterday started first time but runs like a bag of old nails seems to be on 3 cylinders strange as only opend the bonnet to disconnect the battery . done all the usual checks plugs leads ect . only thing i can think of is muck in the carb was a bit low on fuel , thoughts please paul Link to comment Share on other sites More sharing options...
johny Posted July 30, 2023 Report Share Posted July 30, 2023 Does sound like the most plausible possibility although as always our cars are cunning and can throw in electrical faults just when least expected😬 Link to comment Share on other sites More sharing options...
foshi Posted July 30, 2023 Author Report Share Posted July 30, 2023 was running very well , looks like i will have to start checking fuel and electrics have a spark on all cylinders though Link to comment Share on other sites More sharing options...
johny Posted July 30, 2023 Report Share Posted July 30, 2023 It runs rough even on tickover? If so that would have to be a really serious problem with fuel supply as it only needs a whiff at that stage.... Link to comment Share on other sites More sharing options...
Piglet Posted July 30, 2023 Report Share Posted July 30, 2023 Do you think since you reversed up the ramps some crap from the tank has found it's way into the carbs? What's the fuel filter looking like? Alex Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 31, 2023 Report Share Posted July 31, 2023 might have caught some dreaded rubber hose slivers in the float needle valve ...crafty blighters Pete Link to comment Share on other sites More sharing options...
johny Posted July 31, 2023 Report Share Posted July 31, 2023 ha, ha yes first thing to check if the carbs are overflowing! Link to comment Share on other sites More sharing options...
chrishawley Posted July 31, 2023 Report Share Posted July 31, 2023 16 hours ago, foshi said: started first time but runs like a bag of old nails A difficult one because there are so many possibilities but some first-aid steps I'd consider would be: • Add a couple of gallons of fresh fuel, disconnect fuel line at carbs, crank engine and observe for good fuel delivery (into jam jar!) of about a desert teaspoon per pulse. • Remove air filters, check free upward movement of carb pistons, observe linkages for correct operation (including symetrical action on lowering and retruning jets when choke cable operated), top up dashpots. Check rocker cover to intake breather pipes (direct to carbs or PCV depending on engine) for poor fit or splits in rubber. • Remove distributor cap. Inspect for cracks, worn contacts, burnt points (if applicable). • Run engine. Observe for fuel leakage at top of float chambers; may show leakage or just staining (leakage may be more evident just after the engine is turned off). With engine still running disconnect each of the plug leads in turn: if removing a particular lead does not worsen engine running then a problem in that pathway is indicated. Hardly a comprehensive list of procedures but are all £0 except for fuel. If the vehicle has electronic ignition it is not outside the bounds of possibility for it to be 'sparked' by welding, but far from the most likely scenario. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 31, 2023 Report Share Posted July 31, 2023 It nothing else was done then I'd guess either something electrical has been fried by the welding, or else the angle of the car on the ramp has dislodged sediment from a previously unaffected area of the tank and allowed settled particles to enter the fuel lines, especially if the fuel was low. It could be a multitude of things; my Herald ran really rough last month then I found No3 sparkplug hanging out, with no assistance from me. Link to comment Share on other sites More sharing options...
foshi Posted July 31, 2023 Author Report Share Posted July 31, 2023 thanks all will let you know what i find paul Link to comment Share on other sites More sharing options...
foshi Posted July 31, 2023 Author Report Share Posted July 31, 2023 well not going well , started on the button from cold choke in running like on 3 again , blew fuel lines through checked have a good fuel supply all good . so then started the car removed each lead all made the engine note change the back as i touched the lead back onto the plug so seemed all good , coffee time so indoors 30 minutes went back out restarted even worse than before now not running on 3and 4 , took plugs out dry leads ok . suppose next compression test not making sense though drove on the ramp fine was driving well . forgot to mention its a 1300 engine on a single stromberg 150 , thoughts please paul Link to comment Share on other sites More sharing options...
johny Posted July 31, 2023 Report Share Posted July 31, 2023 You could have a look at the carb although the trouble with dropping the float bowl of the bottom is the gasket will almost certainly be damaged and the jet o-rings may not seal afterwards😮 As an easier test how about disconnecting its fuel feed, removing the air filter and with a tight fitting plastic pipe blow through the overflow. If the chamber is full (float valve closed) fuel should only come out of the jet especially if you lift its piston. Once the float level drops air should then start easily coming out of the fuel inlet connection and no more fuel from the jet.... Link to comment Share on other sites More sharing options...
foshi Posted July 31, 2023 Author Report Share Posted July 31, 2023 (edited) have the air filter off do you think it could be carb related number 3 and 4 not firing not come across this before strange it was running badly on 4 at one point , not even my car a favour job now my problem paul Edited July 31, 2023 by foshi Link to comment Share on other sites More sharing options...
johny Posted July 31, 2023 Report Share Posted July 31, 2023 well its the way the problem seems to be moving around and something electrical would be more consistent. Cylinders 1 and 2 dont have any misfiring though? Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 31, 2023 Report Share Posted July 31, 2023 is there any wobble on the dizzy cam spindle due to wear so the points gap varies as it rotates , has the centre carbon brush disappeared ? its unusual to have 2 of the 4 missfire on a single carbed 4 pot to be due to fueling Pete Link to comment Share on other sites More sharing options...
DanMi Posted July 31, 2023 Report Share Posted July 31, 2023 (edited) if a mk4/1500 check that all the fuel hoses are sound as it could be sucking in air rather than fuel particularly any hoses on the top of the tank. Doesn't really apply to mk1-3 as they take fuel out through the bottom of the tank mk4-1500 through the top Pete it is a spitfire so will be twin carb unless US spec or converted Edited July 31, 2023 by DanMi Link to comment Share on other sites More sharing options...
foshi Posted July 31, 2023 Author Report Share Posted July 31, 2023 pete done the dizzy checks all fine , pull the lead on 3 engine runs the same as 4 no backfire engine just jumping all over the place , feels like sticking valves but it cant be ? Link to comment Share on other sites More sharing options...
johny Posted July 31, 2023 Report Share Posted July 31, 2023 11 minutes ago, DanMi said: Pete it is a spitfire so will be twin carb unless US spec or converted converted... Link to comment Share on other sites More sharing options...
DanMi Posted July 31, 2023 Report Share Posted July 31, 2023 2 minutes ago, johny said: converted... ah yes missed that bit Link to comment Share on other sites More sharing options...
foshi Posted July 31, 2023 Author Report Share Posted July 31, 2023 just a thought could the diaphragm cause a problem if has a small hole to be honest all the years i have owned triumphs never had one fail so not sure of symptoms . spoken to owner said was topping up dash pot a lot lately ? Link to comment Share on other sites More sharing options...
johny Posted July 31, 2023 Report Share Posted July 31, 2023 On choke it should idle with minimal assistance from the piston diaphragm so I wouldnt expect a hole to cause any problems until the revs are increased. Also surely it would affect all cylinders? And difficult to see a connection to dash pot oil loss.... Link to comment Share on other sites More sharing options...
foshi Posted July 31, 2023 Author Report Share Posted July 31, 2023 will be something simple i bet will get to it paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 1, 2023 Report Share Posted August 1, 2023 whats the breather system on this conversion ???? this may have a problem/leak to affect the rear 2 pots ?? just what CD is fitted thames barrier choke/starting valve choke/bottom adjuster/top adjuster dashpot only aids acceleration flat spots it wont affect any normal running ongoing loss of dashpot oil has the ring of top adjuster needle there is no real loss from a fixed needle carb just normal service top ups but carbs dont on a single carb dont select which pots to supply Link to comment Share on other sites More sharing options...
foshi Posted August 1, 2023 Author Report Share Posted August 1, 2023 bottom adjuster thames barrier type, breather blocked off breath on rocker to a breather filter , was running fine before going on ramps , just strange it is 2 cylinders 3and 4 not firing paul Link to comment Share on other sites More sharing options...
Iain T Posted August 1, 2023 Report Share Posted August 1, 2023 Surely it can't be a carb or fuel problem as with a single carb all four cylinders would be effected. It must, and I use that word cautiously, be an electrical fault on 3 and 4 only. Try swapping leads and plugs? Iain Link to comment Share on other sites More sharing options...
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