| Author | Message | ||
     George Constantine New User Username: theo Post Number: 2 Registered: 6-2012 |
Hi all, a 1979 Corniche Mk II, A4 Solex carb. I get a very rough idling and bad hesitation when I step on the gas to pull away. It seems to be ok on high revs. I adjusted the carb and timing, all seems well? Can anyone advice | ||
| bobuk Unregistered guest Posted From: 92.40.255.89 |
Check accelerator pump engine off look down chokes work throttle and a squirt of gas should be seen no gas punctured diaphram block some where non return valve fautly There is no adjustment for overall mixture. This is preset by the size of the jets. go to workshop manual and read before you diy. I hope this last line does not sound disrespectful (Message approved by david_gore) | ||
| Nigel Johnson Prolific User Username: nigel_johnson Post Number: 117 Registered: 12-2008 |
Nice to see you commenting again bobuk. Regards, Nigel. | ||
| George Constantine New User Username: theo Post Number: 3 Registered: 6-2012 |
Hi Bobuk, Thanks for your reply. I have a good fuel jet from the pump. I checked the compression, all coming up to around 10. No A2 and A3 plugs are a little oily?. I did replace the stem sills 2,000 miles ago, I was thinking of changing the HT leads again but I'm getting an even spark though, when using a see through adaptor at the end of the HT lead? I,m not certain if it's the Solex carb or ignition now Any further help would be much appreciated Many thanks George | ||
| George Constantine New User Username: theo Post Number: 4 Registered: 6-2012 |
Hi Bobuk, Sorry I forgot to mention in my previous message, when I do remove the HT leads on the A2 and A3 plugs which are oily, I do not notice any variation on the idle or at least, very little and the engine continues to idle rough regardless? Cheers, George | ||
| Paul Yorke Grand Master Username: paul_yorke Post Number: 1028 Registered: 6-2006 |
Hi George, check for air leaks as well. Split hoses and gaskets etc. A2 & A3 leads aren't swapped over are they? Cheers, Paul. | ||
| George Constantine New User Username: theo Post Number: 5 Registered: 6-2012 |
Hi Paul, nice to hear from you. Checked for air leaks etc, and no the leads are not swapped over, I've checked for that. Cheers, George | ||
| bobuk Unregistered guest Posted From: 94.197.127.20 |
Check vacuum to cruise control under washer bottle the speedostat ( aweful name) has sponge springs which turn to dust and cause an air leak connect rev counter to engine at idle note rpm disconnect each plug lead in turn noting the rev drop which should be the same for each cylinder if a2 and a3 are down ie no or little rev drop then check dizzy cap for cross firing and tracking Using sunlight check inside the cap for grey lines which is evidence of tracking I had this on a vauxhall Viva once and after an hour of fiddling they chief mechanic ( who used to a sunbeam talbot racing mechanic in the 1930s) Explain that losing two cylinders could be a dodgy cap he was right and I have never forgotten -- no substitute for years of the spanners This would also explain the oily plugs they can't clean themselves if they don't fire These engine are not spark sensitive like some of the modern stuff so providing the leads are giving a spark and are not tatty then they are good to go I am assuming that 10 on compression means 10 bar or 150 psi (Message approved by david_gore) | ||
| George Constantine New User Username: theo Post Number: 6 Registered: 6-2012 |
Hi bobuk and Paul, Thank you both for your help. I have checked all points you both mentioned. Something very odd came to light whilst checking everything. One of the three bolts securing the AC compressor triangular bracket to the inlet manifold became loose and dropped off. This has left a clean hole straight into the manifold which was sucking-in air. I simply re-tapped the hole and replaced the bolt. The misfiring/flat spot was solved and the engine idle greatly reduced. The car now drives wonderfully and smoothly. Unfortunately I still cannot get the engine to idle 100%? on idle but I suppose I can live with that for now. I thank you both again for you assistance. George | ||
| bobuk Unregistered guest Posted From: 92.40.253.185 |
Engine running spray WD40 around carb base and throttle spindles if the WD40 gets sucked in then you have leak. spindles should have no lift They may have rubber seals (Message approved by david_gore) | ||
| George Constantine New User Username: theo Post Number: 9 Registered: 6-2012 |
Hi bobuk, Thanks for the WD40 trick, I actually did this a while ago but couldn't see any visible signs. I'm now putting it all down to carb' wear Cheers again George | ||
| Benoit Leus Frequent User Username: benoitleus Post Number: 70 Registered: 6-2009 |
Hi George, I had the same problems and in the end I solved it by rebuilding the carbs and then having them professionaly tuned. Benoit | ||
| George Constantine New User Username: theo Post Number: 10 Registered: 6-2012 |
Hi Benoit, Thanks for letting me know about your experience. Well, I've tried everything else,and it seems that my next step would be tackling the carbs (time permitting) | ||
| bobuk Unregistered guest Posted From: 94.197.127.235 |
An important to remember about this carb and other fixed jet carbs is that there are only two ways to adjust the overall mixture and that is by raising the fuel level which will richen the mixture and vica versa Or by changing the jets Both these are factory set Check the petrol level Set rpm 700 max any more will cause bump when selecting gears Setting idle to slow causes rough idle The mixture adjust screw only works on idle when under power the amount of correction from this adjustment has hardly any effect. So adjust this to get engine as smooth as possible cutting fuel back will not give better mpg in fact the opposite happens (Message approved by david_gore) |
