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Very lumpy when cold

Posted: Thu Feb 28, 2019 8:15 pm
by Brucky
Hi gents,
I am after a bit of advice please on my Essex Coupe. Its a problem that’s got gradually worse and has built up over the past two months. On a cold start up if it’s left overnight it’s very lumpy for up to 1 minute now, like it’s only firing on one bank, rough as a badgers, sounds like a Massey Ferguson :) After about 1 minute of driving it smooths out very quickly in just a few seconds, then it runs perfectly. If I start it from hot it’s perfect, it will fire up perfectly no lumpiness. Any ideas would be greatly appreciated.

Thanks John.

Very lumpy when cold

Posted: Thu Feb 28, 2019 8:20 pm
by AJL Electronics
Auto or manual choke?

Very lumpy when cold

Posted: Thu Feb 28, 2019 8:21 pm
by Coupe Racing
Possible gasket beginning to fail and seals when it warms up ?

Very lumpy when cold

Posted: Thu Feb 28, 2019 8:26 pm
by Brucky
It’s a manual choke, would 1 min be quick enough to warm the seals.

Very lumpy when cold

Posted: Thu Feb 28, 2019 8:41 pm
by AJL Electronics
Possibly not enough or too much choke for the ambient temperature. Once it fires, try playing with the choke position to see if things improve.

Very lumpy when cold

Posted: Thu Feb 28, 2019 10:14 pm
by Nigel Clark
My SE6A is quite lumpy on its auto choke for the first 1/4 mile or so from a stone cold start. After that it smooths out.

Different car, different engine and carbs but my Triumph GT6 with manual choke is fussy about how much choke it needs for the first 5 minutes from a cold start.

Maybe you just need to play with how much choke you give the engine. We soon forget that classic engines are not like modern EFi, which run perfectly from cold.

Nigel

Very lumpy when cold

Posted: Thu Feb 28, 2019 10:34 pm
by AJL Electronics
And again, if it is a conversion, you will not have the required fast idle speed. That will certainly make it feel lumpy. It should run at 2000 RPM after a cold start, reducing to about 1250 RPM once the throttle is used. That is how the factory spec carburettor works, the reduced fast idle is tripped when the throttle is blipped.

Nigel, I wonder if your fast idle speeds need adjusting?

Very lumpy when cold

Posted: Fri Mar 01, 2019 7:40 am
by Brucky
Thanks for the suggestions as she’s going into the garage next week for alloy timing gear I will get this issue looked at. She always started perfectly on a fast idle no lumps from cold. This has crept in over the past few months regardless of the outside temp. I am hoping it’s something that needs adjusting or carb related

Very lumpy when cold

Posted: Wed Apr 03, 2019 5:44 pm
by Brucky
Took took the Coupe to a carb specialist and ended up getting a new carb. Apparently it was completely worn out. It’s now set up properly. Starts from cold on the button no lumpiness. It drives a lot smoother and is more responsive and it idles significantly lower than before. It’s mad that one thing can make such a difference to the driving experience