Bullman Posted April 22, 2001 Share Posted April 22, 2001 I have changed the cam from a 234 to 244 ,ignition timing is set at 14 degrees b.t.d.c. lucas ignition, unleaded fuel,octane booster additive. The exhaust is backfiring at idle,there are yellow flames within the air filters prompting me to switch off.The plugs quickly foul up making restarting difficult without taking the plugs out cleaning them,that is if the battery doesn't go flat. please advise. thanks Bullman. Bullman Link to comment Share on other sites More sharing options...
John Whyman Posted April 23, 2001 Share Posted April 23, 2001 I would be tempted to check the valve clearances very carefully esp inlet. Link to comment Share on other sites More sharing options...
elie boone Posted April 23, 2001 Share Posted April 23, 2001 Bullman, check your ignition ( firing order 1-2-4-3 ) Link to comment Share on other sites More sharing options...
STEVE GILBERT Posted April 24, 2001 Share Posted April 24, 2001 I just had this and it was no more than Carbs out of balance(badly) after the re-build Link to comment Share on other sites More sharing options...
eric Posted April 28, 2001 Share Posted April 28, 2001 Hi I had the same problem on a stage 2 Head from Burton and a A2 Cam in my 1600 sprint engine The head is unleaded and I run 98 The flames went out from the exhaust and the 4 int 1 became red. And it was also spitting in the carbs The problem was due to the idle jet which are too small I have in the Caterham kit 50/9 and now with 60/8 all is perfect I know this is strange but now everything is OK I live in France in Marseille, in winter Main is 120 and air 180 in summer Main is 115 and air 180 I hope my mail will help eric Link to comment Share on other sites More sharing options...
Bricol Posted April 28, 2001 Share Posted April 28, 2001 I would second the firing order arrangement. I lost a valve seat insert which jammed the valve open. Re-did head, rebuilt engine - 234 cam, 40's etc, exactly how it was before - same as you - flames and backfires at the same time. Flattened three batteries. Dismantled timing case to check cam timing (although hadn't touched it) - seemed to be out a touch - reset it. stil same problem. Spent over an hour re-checking everything again. No luck- gave up and had tea. Came out again, re-checked - nothing wrong. Put the plug leads on the right way round - started first time and ticked over nicely. Ever get that feeling? Bri Link to comment Share on other sites More sharing options...
Rigs Posted April 30, 2001 Share Posted April 30, 2001 Hi from South Africa. I would start checking the timing, leads, dis. cap etc. and then check the carbs for balancing, leaks, jet setups, etc. It will take some time to do this but it is the proper way. Cheers. Link to comment Share on other sites More sharing options...
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