out of ideas

spike4073 · Feb 16th, 2011, 12:02

my 340 dl has run lumpy for years , its been off the road for a while now and im working on getting it running and now its so lumpy when idle that the mot station wont pass it,

ive already replaced a bent valve and checked all the clearences so i know theres no problem there,

the carb has been stripped and re-built so short of a little tweaking i dont think theres much else that can be improved there,

plugs are all brand new so i know they ae ok,

ive had the pressure in the cylinders checked and thats ok,

i am aware that it could do eith a new dizzy cap , rotor arm and some new leads, i know these things can cause poor idle/running but cant beleive that they are causing it to idle as lumpy as it is (like a tractor)

any ideas anybody???

cheers

Joe Harding · Feb 16th, 2011, 12:13

duplicate reply

Joe Harding · Feb 16th, 2011, 12:22

Forgive my ignorance, I'm sure the 340DL is 1.4 but I need to check.

You haven't mentioned the anti-run on solenoid on the carburettor. Checked that?

Check the brake servo vacuum assist. If that leaks you'll hear it hissing esp. when you depress the brake pedal. Check pipe and non-return valve.

Check breather pipes to rocker cover. If they're blocked or leaking you can kiss goodbye to a smooth idle. Especially that one that goes to the lower port on the carb. and the tee-piece on the rocker cover.

You've had the carb refurbished, have you checked the base for flatness? Also that resin gasket that goes between the carb hot seat and the inlet manifold. They can develop tiny cracks. I smeared mine in gasket compound with no ill-effects.

Hope this helps.

spike4073 · Feb 16th, 2011, 12:22

yeah its 1.4,

the idle solenoid has been checked and works yes, sorry i forgot to mention it,

all air hoses were checked a while back and are all good as far as i know,

TonyS9 · Feb 16th, 2011, 12:37

There is a breather pipe running into the manifold just below the carb (or maybe into the carb body). Make sure there is a restrictor between it and the rest of the breather system.

There are 2 types, early cars had a little plastic tube inside the pipe with a small hole in it. Later cars have the restriction in the T-piece on the valve cover.

Anyway block off or clamp the pipe to test it. If it improves things you need to readjust your mixture with everything correct.

Hair bear · Feb 16th, 2011, 19:15

HT leads in the right order? Just a thought...

VND · Feb 16th, 2011, 19:52

Warped carb base?
Any air leaks along the base of the carb?

Carb bolts possibly stripped?

Floats ok?

Clan · Feb 16th, 2011, 20:25

The weber carb on the 1400 was never one for warping the flange , that was saved for the 1700 !

VND · Feb 17th, 2011, 07:18

Quote:

Originally Posted by Clan

The weber carb on the 1400 was never one for warping the flange , that was saved for the 1700 !

Two of mine have mind.
I must just be unlucky.

spike4073 · Feb 17th, 2011, 11:38

there arent any air leaks that i can find, theres no warping,

yeah the leads are in the right order,

my mechanic has told me the carb may be nackered as when he tries to adjust the mix to improve idle it makes little to no difference so hes pushing the idea of a new carb,

trouble i find is that mechanics in my experience sometimes suggest un needed new parts to get more work,

cant convince myself it needs a new one, its only done 60k and the carb was recently re-built so i find it hard to beleive thats to blame,

stumped...

Feb 16th, 2011, 12:02	#1
spike4073 Member Last Online: Nov 26th, 2011 11:12 Join Date: Aug 2008 Location: sheffield	out of ideas my 340 dl has run lumpy for years , its been off the road for a while now and im working on getting it running and now its so lumpy when idle that the mot station wont pass it, ive already replaced a bent valve and checked all the clearences so i know theres no problem there, the carb has been stripped and re-built so short of a little tweaking i dont think theres much else that can be improved there, plugs are all brand new so i know they ae ok, ive had the pressure in the cylinders checked and thats ok, i am aware that it could do eith a new dizzy cap , rotor arm and some new leads, i know these things can cause poor idle/running but cant beleive that they are causing it to idle as lumpy as it is (like a tractor) any ideas anybody??? cheers

Feb 16th, 2011, 12:13	#2
Joe Harding Premier Member Last Online: Today 07:45 Join Date: Oct 2010 Location: Bristol	1.4 or 1.7 duplicate reply Last edited by Joe Harding; Feb 16th, 2011 at 12:23. Reason: duplicate reply

Feb 16th, 2011, 12:22	#3
Joe Harding Premier Member Last Online: Today 07:45 Join Date: Oct 2010 Location: Bristol	1.4 or 1.7 Forgive my ignorance, I'm sure the 340DL is 1.4 but I need to check. You haven't mentioned the anti-run on solenoid on the carburettor. Checked that? Check the brake servo vacuum assist. If that leaks you'll hear it hissing esp. when you depress the brake pedal. Check pipe and non-return valve. Check breather pipes to rocker cover. If they're blocked or leaking you can kiss goodbye to a smooth idle. Especially that one that goes to the lower port on the carb. and the tee-piece on the rocker cover. You've had the carb refurbished, have you checked the base for flatness? Also that resin gasket that goes between the carb hot seat and the inlet manifold. They can develop tiny cracks. I smeared mine in gasket compound with no ill-effects. Hope this helps.

Feb 16th, 2011, 19:15	#6
Hair bear Junior Member Last Online: Apr 7th, 2024 11:21 Join Date: Feb 2011 Location: Hampshire	HT leads in the right order? Just a thought... Last edited by Hair bear; Feb 16th, 2011 at 19:41.

Feb 16th, 2011, 19:52	#7
VND Now with added T4 Last Online: Jan 4th, 2020 20:25 Join Date: Dec 2008 Location: Newcastle Upon Toon	Warped carb base? Any air leaks along the base of the carb? Carb bolts possibly stripped? Floats ok? __________________

Feb 16th, 2011, 12:37	#5
TonyS9 Premier Member Last Online: Apr 9th, 2024 21:44 Join Date: Jul 2009 Location: Holywood	There is a breather pipe running into the manifold just below the carb (or maybe into the carb body). Make sure there is a restrictor between it and the rest of the breather system. There are 2 types, early cars had a little plastic tube inside the pipe with a small hole in it. Later cars have the restriction in the T-piece on the valve cover. Anyway block off or clamp the pipe to test it. If it improves things you need to readjust your mixture with everything correct.

Feb 16th, 2011, 20:25	#8
Clan Experienced Member Last Online: Yesterday 23:35 Join Date: Jun 2007 Location: L/H side	The weber carb on the 1400 was never one for warping the flange , that was saved for the 1700 ! __________________ My comments are only based on my opinions and vast experience .

Feb 17th, 2011, 11:38	#10
spike4073 Member Last Online: Nov 26th, 2011 11:12 Join Date: Aug 2008 Location: sheffield	there arent any air leaks that i can find, theres no warping, yeah the leads are in the right order, my mechanic has told me the carb may be nackered as when he tries to adjust the mix to improve idle it makes little to no difference so hes pushing the idea of a new carb, trouble i find is that mechanics in my experience sometimes suggest un needed new parts to get more work, cant convince myself it needs a new one, its only done 60k and the carb was recently re-built so i find it hard to beleive thats to blame, stumped...

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)