kiwi-jim Posted December 15, 2018 Report Share Posted December 15, 2018 I need your thoughts The rebuild of my 62 TR4 is well on the way and its sort of back on the road....except for the fact the engine is not running well Heres the story, full engine rebuild, with a tweaked cam, ( wasn't asked for but seems to be what I ended up with), new distributor, ( the Indian reproductions all I can find at present) new coil, etc. Car starts easily, but runs really rough, when cold with backfires, and missing. when it gets warmed up starts to run better. The carbs have all been rebuilt by a local expert and fuel seems to be flowing well. Had the whole set up into a reputed rebuild and restoration company to tune. Now one moment it runs fine, the next it starts backfiring and missing again. On a road run we can one moment be running sweetly at 100kms/hr, and the next it will lose power and backfire and fart around before picking up again and running sweetly again. I have rechecked timing , gap settings, changed plugs, tried the distributor cap and wires off my TR3 ( it runs fine) but its all still misbehaving intermittently. So i guess its either spark/ electrics or fuel related issue, I'm just lost as to what. What am I missing or perhaps should recheck. Quote Link to post Share on other sites
Ian Vincent Posted December 15, 2018 Report Share Posted December 15, 2018 Backfires suggest timing issues to me. Do you have anything loose near the distributor that might be grounding the low voltage circuit intermittently? Rgds Ian Quote Link to post Share on other sites
Z320 Posted December 15, 2018 Report Share Posted December 15, 2018 I would first check this: is each plug on the correct spark plug? But if this is the case you should realise this at once. Quote Link to post Share on other sites
RogerH Posted December 15, 2018 Report Share Posted December 15, 2018 As it runs well one moment and then bad the next it can't be anything that is fixed - Valve timing, etc. Check ALL the connection in the Dizzy especially the soldered tag on the flexible LT wire. Check all ignition connector joints. Have you got oil in the carb dash pots Roger Quote Link to post Share on other sites
Rob Salisbury Posted December 15, 2018 Report Share Posted December 15, 2018 Condenser? ....... even new ones are not necessarily good ones, ...... try a known good one. Cheers Rob Quote Link to post Share on other sites
RogerH Posted December 15, 2018 Report Share Posted December 15, 2018 2 minutes ago, Rob Salisbury said: Condenser? ....... even new ones are not necessarily good ones, ...... try a known good one. Cheers Rob .............and rotor and coil Roger Quote Link to post Share on other sites
Waldi Posted December 15, 2018 Report Share Posted December 15, 2018 Like above, my bet is on the electrical system, and in particular woven earth wire (inside the dizzy) or rotor or condensor, or coil. Check if all connections are solid. If you suspect electric feed, you could connect a multimeter with long wires to the + on the coil and drive the car. If voltage drops when error occurs, you can concentrate on that ( or rule it out). since it runs rough when cold and does better when warm, mixture cannot be ruled out completely, but I would first concentrate on the electrics. Regards, Waldi Quote Link to post Share on other sites
rcreweread Posted December 15, 2018 Report Share Posted December 15, 2018 Indian dizzies don't have the best reputation for reliability so I would try a different one to see if it makes any difference - are you running SUs or Strombergs - if the former, check the oil in dashpots, if the latter check very carefully the diaphrams. Also check fuel flow to the carbs - is there any **** partially blocking the fuel lines? Having said all that, I agree it sounds more electrics related - how about trying a direct cable from battery to coil to rule out any issues with the ignition switch and associated circuits. cheers Rich Quote Link to post Share on other sites
Tr4aJim Posted December 15, 2018 Report Share Posted December 15, 2018 I quick thing to try is running the engine with the bonnet open, in the dark. Look for any arcing. Something may be finding an intermittent path to earth. Jim Quote Link to post Share on other sites
Dic Doretti Posted December 15, 2018 Report Share Posted December 15, 2018 Try fitting your TR3 distributor, a known quantity and see what it is like on the road. Cheers Richard Quote Link to post Share on other sites
kiwi-jim Posted December 15, 2018 Author Report Share Posted December 15, 2018 Brilliant thanks everyone, like you I do suspect the electrics and in particular the dizzy somewhere, I will start the process of trying all your suggestions . However it will be a few weeks before I can do it and post a reply off the answer as I fly to Germany for Christmas in 48 hrs. Thanks again to everyone , I will eventually let you know the culprit. Have a great Christmas everyone cheers Quote Link to post Share on other sites
ctc77965o Posted December 15, 2018 Report Share Posted December 15, 2018 +1 Condensor Quote Link to post Share on other sites
kiwi-jim Posted December 16, 2018 Author Report Share Posted December 16, 2018 Hi everyone, your prompt responses got me to race out and try some of what you had suggested. So I started checking my connections , the lead from the Dizzy to the coil had spade connnections that seemed to easily slip on and off , so I made up a new connection with new spade terminals, plus I changed the condenser for another that was sitting on an old unused distributor. Flicked the starter and straight away you can see and hear the diffference, took the car for a short run and it was a different beast. There is still a bit of "run on "occurring but your suggestions have really helped. Thanks so much everyone. Have a great Christmas. cheers Quote Link to post Share on other sites
ianc Posted December 16, 2018 Report Share Posted December 16, 2018 Don't buy distributor electrical parts (rotor arm, condenser, points) in "Lucas" boxes unless very old stock. Get these items from Martin Jay (Distributor Doctor), who gets them made to the correct specification. Some condensers have only half the required material inside the can, some points are made with inferior material in heel and contacts (so wear rapidly), and some rotor arms break down (short). I had two modern "Lucas" rotor arms fail before Martin produced his rotor arms. Ian Cornish Quote Link to post Share on other sites
harrytr5 Posted December 16, 2018 Report Share Posted December 16, 2018 There is some fake red rotor arms about. I always buy from the source ie.. Martin Jay (Dizzy Doc) who now stamps DD on the rotor arm.( yes they can fake that) Regards Harry Quote Link to post Share on other sites
Mr Blue Sky Posted December 16, 2018 Report Share Posted December 16, 2018 One other thing that you may want to consider, is the coil, as they heat up the insulation can break down and give the symptoms you describe. The previous forumites are right to point out the condenser/rotor arm too. My wheeled vehicle mechanics course instructors at REME Borden always said check those items 1st when fault finding a misfiring engine. One last one, if your coil is now on the inner wheel arch as opposed to the block, check the dipstick isn't touching the terminals - don't ask how I know. Regards, Laurence Quote Link to post Share on other sites
Ian Vincent Posted December 18, 2018 Report Share Posted December 18, 2018 On 12/16/2018 at 8:50 PM, Mr Blue Sky said: One last one, if your coil is now on the inner wheel arch as opposed to the block, check the dipstick isn't touching the terminals - don't ask how I know. That's where I was coming from with my original response. Don't ask how I know either! Rgds Ian Quote Link to post Share on other sites
Mr Blue Sky Posted December 18, 2018 Report Share Posted December 18, 2018 Ian, my apologies, I had no intention to plagiarise your earlier post. I have since opened the split section of the dipstick so that it cannot rotate easily. Regards, Quote Link to post Share on other sites
Ian Vincent Posted December 18, 2018 Report Share Posted December 18, 2018 21 minutes ago, Mr Blue Sky said: Ian, my apologies, I had no intention to plagiarise your earlier post. I have since opened the split section of the dipstick so that it cannot rotate easily. Regards, Not a problem, I was just empathising with your experience. I also had to adjust the split section of the dipstick along with a bit of judicious bending adjustment. Rgds Ian Quote Link to post Share on other sites
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