Running lumpy at mid revs

[roy the potter]

Hi, my gtl has been running lumpy at mid revs especially on inclines, then the other day it ran really nice as it did when I first bought it, but the next day it started running lumpy again. Before the bad running I changed old femsa distributor for a new ducellier, leads, plugs, air filter, fuel filter. and new manifold gasket, could it be the carb? Hope someone can help. Thanks Roy

 

[mojobaby]

Hi Roy, can you define "lumpy". Do you find that you now have to change down a gear to go up a hill, where before it wasn't a problem?
If so, it's a timing problem. Check your points gap again and advance the timing a fraction

 

[benchseat]

One of my R4s started to run lumpy, though in my case it was when idling.

The problem was a blown cylinder head gasket.

Take the top off the radiator header bottle, run the engine. If the gasket is blown you will see a continuous stream of bubbles running into the bottle from the radiator feed pipe.

 

[roy the potter]

Hi, it is a stuttering king of lumpiness if you know what i mean at mid revs, it doesnt do it at low revs or not so much at high revs and why would it run so sweet on the other day and then go gack to stuttering, hope this defines the prob a bit more, thanks.

 

[roy the potter]

Hi, it is a stuttering king of lumpiness if you know what i mean at mid revs, it doesnt do it at low revs or not so much at high revs and why would it run so sweet on the other day and then go gack to stuttering, hope this defines the prob a bit more, thanks.

Ok, just cleaned the carb, lots of black residue in bottem of float chamber, gave it blow out with the compressure gun, then gave her a run. Stuttering stopped but now running a bit flat at mid revs, as in not pulling very well! Tried advancing timing but still the same. What next!!

 

[Cornish4]

Hi there Roy, to be fair you did renew quite a lot of bits so it could be any one of these that is giving trouble. If your car was running "ok" before maybe refit the Femsa dizzy, if all ok, then you know it's probably the Ducellier one that's giving the trouble. New condensers are notorious for being faulty. Have you checked for air-leaks around the carb, and not trying to be clever here, but is the fuel filter the right way around. I think it's going to be a case of trial and error. Good luck, Brian.

 

[roy the potter]

Hi, yes there was a problem before changing everything, its just strange that it ran really nice for one day last week. Think i'll take it to the mechanic now!! Thanks for reply's.

 

[Sprackers]

Sounds familiar. Runs perfectly then next day rubbish. Before you spend the cash for a mechanic. You are going to have to start at the beginning.
I am sure you have taken the plugs out and clened them.
I Changed the whole lot and found out it was the plugs and the new leads wernt actually on correctly!!
And what is teh ref number on the side of the Ducellier?