Poor idle

[cass3958]

This is a very good post. Let's get one thing straight ~ No. 1 cylinder is located closest to the firewall with a firing order of 1-5-3-6-2-4.

Bit harsh Glyn, I do not think we need to say "Let's get one thing straight" it is what it is and it says so in the Workshop manual! Excellent information and lets leave it at that.

[Glyn Ruck]

Sorry ~ My blunt South African & oil company ways ~ we don't think twice about it & don't mean to offend. Good catch, I will modify.

[Glyn Ruck]

Duly modified.

[cass3958]

Thank you.

[JCS]

Awiedie

You will probably be aware, but you need to take care if you intend to use compressed air down the jet well. Excessive pressure down the jet on a HD6 S.U could well rupture the jet diaphragm, or distort the float and float arm.

If the carburettor checks do not show any fault it might be fruitful to check out the exhaust and see if you are experiencing a partial blockage. I have not examined the internal exhaust baffle arrangement on an S Type, but on some types a faulty baffle rotted out at the base and intact at the top can act like a flap. In the early days although these engines may run when throttled up, they will not stabilise and idle well. This problem more often affects vehicles that have been in store or run up for a short time when exhaust acids eat the lower parts of the baffles.

[awiedie]

Thanks JCS. I haven't tried it yet but if I do blow a LITTLE compressed air it will be down the slow idle bore, not the jet. Still waiting for some decent weather. As far as the exhaust baffles possibly rotting out is concerned, that's a last resort and to be saved for another day. Nothing good ever has come from me doing work on the exhaust system. At the moment, I'm trying to sew up a new tonneau cover for my MGA.

[awiedie]

Finally back to working on my poor idle/stalling problem. I put some Techron in each tank as recommended by Glyn and have run the car several times since. It will start up just fine on choke and most of the time settle on about 600rpm when the choke kicks out. Idle goes up slightly as the car warms up. Now, if I step on the throttle to get the car to 1500rpm or so and then take my foot off the pedal quickly, rpms drop down, down - to nothing! Car starts right up with the touch of the button and goes to around 600rpm again. Repeat. Any additional thoughts? This is driving me nuts.

[Orlando St.R]

I put some Techron in each tank as recommended by Glyn and have run the car several times since.

Yes, that does sound very frustrating, Alan. Have you actually driven it anywhere? Or is this just running the engine in the garage?

[Glyn Ruck]

If your problem is deposit related. Techron works on heat soak cycles. How many times have you run the engine up to operating & allowed it to cool to ambient Alan?

[NigelW]

Very frustrating experience. As mentioned in Orlando's post , have you tried it on the road under load yet? As you've exhausted all the carb/fuel checks can I suggest you have a look at the electrical side of things especially if your using points, try changing the condenser in the distributor. If this is faulty it would definitely show up on the road under load, I've experienced similar problems such as this with other cars in the past if they've been sitting for some time.