Matt306 Posted September 28, 2014 Share Posted September 28, 2014 Hello everyone here for some ideas on Carb Problems.For the first time since the car was on the road (a long time ago) I ran the engine up to temperature. When warm I thought i would check the mixture and timing. Timing easily adjusted with the use of my Gunson light with timing advance function.The carb though is another issue. I rebuilt this carb with service kit, not included was a new metering needle or jet. I put in a new seals and gaskets needle valve for the float chamber. Now I tested the carb mixture by lifting the air valve slightly the engine picked up noticeably so I back off the screw on the base, no change, again , no change ... in fact which ever way i went the mixture wouldn't lean off screwing up or down.Took the carb off, floats fine, no holes , checked needle valve by blowing down the inlet , no noticeable leaks. Floats 18mm above flange of carb body. Diaphragm fine...Is it time for a new jet and metering needle or should i be checking something else? Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted September 28, 2014 Share Posted September 28, 2014 What carb is it? Quote Link to comment Share on other sites More sharing options...
Matt306 Posted September 28, 2014 Author Share Posted September 28, 2014 That would help wouldnt it! Stromberg CD150 as fitted to Herald 13/60... nothing special! Quote Link to comment Share on other sites More sharing options...
DougBGT6 Posted September 28, 2014 Share Posted September 28, 2014 Ah.... Mine are much later, temperature compensators and all that malarkey. So I'm not the expert on your one. However things that caught me out were: The carb to manifold gasket, these can be put on four ways, back to front, upside down, back to front AND upside down and finally, the right way. There is a cut out on the gasket to line up with a hole in the carb body. I put mine on wrong and got exactly the symptoms you describe. There again yours may not have the hole! ;DThe inlet manifold gasket may be leaking which will also mess up the mixture. I think even with a worn jet and needle you should be able to screw it down to run lean. How about the choke? Did that get overhauled? If that's not right you're gonna have trouble with the mixture. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted September 28, 2014 Author Share Posted September 28, 2014 Thanks for the reply, it all came apart and all given a damn good clean. The Choke (manual on these) came out and was cleaned too.As to the gaskets that could be an issue but wasn't aware it made much of a difference as they as item 63 here; http://www.canleyclassics.com/?xhtml=xhtml/diagram/herald1360carburettor.html&xhtmlcatalogue=xhtml/catalogue/herald1360.html&category=engine&xsl=diagram.xsl Quote Link to comment Share on other sites More sharing options...
Dave1360 Posted September 28, 2014 Share Posted September 28, 2014 Have you confirmed that the air valve isn't sticking and the jet's been centralised correctly?When I rebuilt my CD150, I replaced the jet and needle as it seemed a good idea while it was all in pieces. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted September 28, 2014 Author Share Posted September 28, 2014 Dave i think i have but i think i might not have done it properly Quote Link to comment Share on other sites More sharing options...
Dave1360 Posted September 29, 2014 Share Posted September 29, 2014 I also found that even slight over-tightening of the top cover screws sometimes caused the air valve to stick and not drop cleanly. It could be useful to get that right first without the jet fitted, and then get the jet centred. Another possibility is the needle - is its shoulder dead flush with the bottom of the air valve? Common sense tells you to drop it into the hole as far as it can go before clamping it, but that'd cause a rich mixture too. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted September 29, 2014 Author Share Posted September 29, 2014 I noticed that the air valve seemed tighter on with the screws tight. I thought they needed to be tight down to stop air leaks? Quote Link to comment Share on other sites More sharing options...
Dave1360 Posted September 29, 2014 Share Posted September 29, 2014 Sounds familiar. I found that if you keep tightening them gradually in turn whilst sliding the valve up and down then you can get to a point where the screws are nipped up but not stupidly tight and the valve still moves freely. This is all with the jet either removed or loose, of course. It seemed to work out ok for me anyway. Quote Link to comment Share on other sites More sharing options...
Matt306 Posted September 29, 2014 Author Share Posted September 29, 2014 I ordered new metering needle and jet to be sure. Before removing the jet and needle i backed off the nut underneath the float bowl screwed jet up and dropped the needle into the jet, did it a couple of times. Then placed a drift down the damper tube and held the air valve close an nipped up the nut. The air valve seemed to move better.The metering needle looked quite grubby so i suspect for £20 its worth replacing them, especially at the price of petrol! Quote Link to comment Share on other sites More sharing options...
Matt306 Posted October 5, 2014 Author Share Posted October 5, 2014 New Jet and Needle and jet properly centred seems to have helped Quote Link to comment Share on other sites More sharing options...
logicaluk Posted October 5, 2014 Share Posted October 5, 2014 Glad to hear it. Quote Link to comment Share on other sites More sharing options...
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