randall977 Posted March 8, 2014 Report Share Posted March 8, 2014 Hi, I haven't had my TR for a while as I've been working on another car. One thing I've really missed is the helpful and informed advice I got on this forum when I had my TR. It's a bit cheeky but I would love some views on the condition of my plugs after a 10 mile journey... I think something isn't quite right on my car as when I go above 30 mph and it sounds like it's mis-firing. It's definitely not the electrics, I have eliminated that side of things. It could be fuel or air supply, the two carbs are in great condition but maybe the electric SU double pump is not keeping up (if that's possible). Below is a photo of my plugs, they are in order with number 6 being by the windscreen (cylinder 6). I would be interested in your thoughts, in particular on 2 and 5; 5 appears wet around the thread and 2 appears blacker than the others. Apart from that what does the colour tell you, as according to quite a few diagrams on the net these appear to be good??? Also, compression test shows fairly uniform compression but I'm not ruling that possibility out as a small amount of coolant has come out of the header a few times but no overheating. Many thanks! Quote Link to post Share on other sites
Fireman049 Posted March 8, 2014 Report Share Posted March 8, 2014 Hi Randall ~ The plugs look perfectly normal to me ~ a good brown colour (not Black or White). I wish my plugs looked like that ~ mine are always Black even though the mixture setting is OK! Regards ~ Tom. Quote Link to post Share on other sites
John L Posted March 8, 2014 Report Share Posted March 8, 2014 (edited) They look good to me As a matter of interest what make and model are the plugs, and which carbs do you have? John Edited March 8, 2014 by John L Quote Link to post Share on other sites
randall977 Posted March 8, 2014 Author Report Share Posted March 8, 2014 Hi, yes they appear okay to me too? It's a 1962 AML Rapide 4.0 with 2x Solex PHH44's. If the pump was not keeping up with demand when under load would this show in the plugs - would they look lean? Quote Link to post Share on other sites
Peter Cobbold Posted March 8, 2014 Report Share Posted March 8, 2014 (edited) This is the DB4 engine, right? Extra £££s. So best to be certain!! If you removed the plugs after a time at tick-over you are measuring tickover mixture, not mixture under load. To get an idea of mixture under load do a 'plug chop' - while under load, kill the ignition and coast to a halt ( unless you have a ig sw that is a steering lock!!). Look at plugs at road side. BUT if its misfiring - as it is - then it wont tell you a lot about mixture. With an engine that expensive I'd measure the mixture by fitting a wide band sensor, UEGO. Best to be certain. Even so that wont work correctly of the engine is misfiring. So first I think you need to correct the misfire. You have eliminated spark and timing, including centrifugal advance?. So your concern about fuel pump not being adequate might cause a lean mixture, and they are potentially dangerous. There is perhaps some evidence from those the tiny silvery spots on the earth strap- very obvious on #3, also on #5 (- zoom the image). If its molten aluminium you have a problem that really needs sorting urgently. Lean mixtures can detonate - and those blobs of ali have come off the piston crown ( if that's what they are). Before running under load again, clean out all fuel filters, get a tank full of highest RON fuel you can find, richen the carbs, fit new plugs, and see if the misfire goes. Dont run it misfiring for ten minutes. Retard the spark to see if it goes away. Once the misfire has gone measure the mixture. Lots of info on reading plugs here: http://www.crankshaftcoalition.com/wiki/Reading_spark_plugs http://brianesser.com/technical-information/the-ultimate-guide-to-spark-plugs/ (some of if seems OTT to me - like the timing marks on earth strap) Peter Edited March 8, 2014 by Peter Cobbold Quote Link to post Share on other sites
randall977 Posted March 8, 2014 Author Report Share Posted March 8, 2014 Hi Peter, thank you for taking the time to offer advice, it's very helpful. I don't think it is molten aluminium but chips in the carbon (the plugs are new and shiny under the carbon) - but I will be sure to carefully check tomorrow! Quote Link to post Share on other sites
PaulAA Posted March 9, 2014 Report Share Posted March 9, 2014 A '62 Rapide? You're a lucky man. I know this is not the right place, but would you post a couple of images of the beast? Paul Quote Link to post Share on other sites
Peter Cobbold Posted March 9, 2014 Report Share Posted March 9, 2014 Hi Peter, thank you for taking the time to offer advice, it's very helpful. I don't think it is molten aluminium but chips in the carbon (the plugs are new and shiny under the carbon) - but I will be sure to carefully check tomorrow! If you're worried about water loss coming from poor head gasket check the tell-tail weep holes. Quote Link to post Share on other sites
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