Tipidave Posted August 6, 2018 Report Share Posted August 6, 2018 Hi All having just collected my new herald 1200 I have worked my way round a poor starting problem. Amongst the usual adjustments (inc valve clearances that were all too tight) a new hi torque starter motor as helped enormously. However compression test cold ( can't run up to temp until new thermostat cover arrives) revealed some interesting and low results as follows 1= 110 psi 2= 70 psi 3= 55 psi 4=90 psi other than a very tired engine, does this likely mean a gasket fail between 2 and 3? Before leaping into a full rebuild, would a head off visual inspection for scoring, relap of valves, skim and new gasket be a logical first step .... or am I simply putting off the inevitable? Your thoughts greatly appreciated ? Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 6, 2018 Report Share Posted August 6, 2018 So this is a cold test ? Was the throttle held open ?? Whats the running problems ? Mis fire lumpy , lethargic or what ? Is this with a std solex carb ? And yes HG bridged would give low on 2 and 3 Pull a head nut off look at the state of the washer if its all deformed by a now lost torqure on the nut then a gasket failure is very likely In the cost of things I would give the head and valves a good appraisal before you jump into deep pocket sydrome Link to comment Share on other sites More sharing options...
Nick Jones Posted August 6, 2018 Report Share Posted August 6, 2018 You need to do another compression test, preferably with the engine hot, but more importantly including a second round with a couple of spoonfuls of oil added to each cylinder as a wet test. If the compressions are significantly higher on the wet test, this suggests rings/bores are an issue. Little change implies valve seating issues. The latter is quite likely given the tight tappet settings you report. Nick Link to comment Share on other sites More sharing options...
Tipidave Posted August 6, 2018 Author Report Share Posted August 6, 2018 Yes throttle open poor start from cold... seems to run quite sweetly but some blue exhaust fumes when under load ( reported by guy following me back home on collection) feels a bit lacking in power (but it is a few years since I last drove one ) haven't driven above 55mph because a wheel wobble needs sorting... then I found corroded thermostat housing that leaked a bit so waiting for replacement before further investigation Link to comment Share on other sites More sharing options...
Tipidave Posted August 6, 2018 Author Report Share Posted August 6, 2018 Ah thanks nick.. makes sense. By a little oil do you mean a few drops? Or a tablespoon? I will wait to sort thermostat housing before conducting the test hot. ? Link to comment Share on other sites More sharing options...
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