Series 3 2.25 Petrol stalls at idle

[rxl123]

Hi all. Hoping you can help. I am sure this has been asked before but I cannot find it in my searching.

Got a '72 S3 Petrol. It had been laid up for a while during the snow through a flat battery. Fired it up and petrol was leaking out the carb housing. So changed the carb. All seemed rosy.

First journey out of the drive was last week when it went 15 miles along an A-road at a steady 45 (near flat out!)

It seemed to handle that ok - a little tired maybe, but as soon as i came to the junction and the revs dipped below about 1500 it just stalled. I suspected was a bit low on power as well but may have invented this. So for the rest of the journey every time revs dipped below 1500 it cuts out. Very annoying. It still starts spot on, but then stalls.

Any suggestions on where to look? As it had been laid up for about 4 months anything may have gone. Temp was running just below the red on the gauge so a little higher than it should be, but it didn't get any hotter and go into the red.

No smoke from exhaust. All seemed ok.

Options I am aware of (but don't know how to check!) below, but am guessing there is a sensible order to rule out issues - don't really want to jump straight into head gasket replacement as a first diagnosis. Your thoughts and comments welcomed!

- Maybe I Didnt attach new zenith properly. Worked for a bit but could now be leaking air at joint - How do I check this?

- Head gasket shot - How do I check this?

Ok so its not many solutions I am aware of. Any others please? Thanks

Jack

[Quagmire]

I'd start with the simple things first- I think it's pretty hard to do a head gasket (comparatively) on a series motor.

You might have a blocked idle jet? If there is crud floating around in the tank or its been run dry then this happens. Has happened to me more than once in my series2, back in the days when i was a poor student and used to fill petrol £5 at a time...

I'd also try a different coil- recently I had a problem where mine would conk out when warm. Turned out to be the coil going south.

If you really did get it hot then checks for headgasket would be the usual things, compression test, are the hoses pressurising?

[samtope]

Perhaps check the ignition timing too. I was surprised at how far out mine had gone, of its own accord. This will equal lost power too. I loosened the collar at the base of the distributor while the engine was warm and twisted the body until the revs were at their highest peak. Then a tiny twist clockwise to retard the ignition to compensate for when you're driving along. Just a few degrees. Sorry if I'm showing granny how to suck eggs, I was just pleased with the results after following these steps. The temp gauge is also not to be trusted. Mine shoots it to the red immediately on turning the key.. Also take a spark plug out and compare it to the hundreds of pictures of used spark plugs on-line. Their condition will tell you all about the health of the engine and maybe why it keeps stalling..

[errol209]

Can I suggest the very obvious?

Did you adjust the new carb when you fitted it?

Do you know its history (i.e. are you sure its a good 'un?)

[rxl123]

Thanks for the comments.

On the blocked idle jet, not sure how to check this - do I need to take apart the whole carb or is there another way?

I will try a new coil - even if only preventatively. Seems like a good plan.

Hose are pressurising. May try the compression test.

Samtope - definitely not doing the suck eggs thing - comments are perfectly at my level. Will furtling with the distributor.

Errol - In terms of the carb, was a shiny new one out the box. Didnt know I had to adjust it other than set up idlign speed. It went on fine, fired up great and in driving locally around the villages behaved perfectly over the 5 or 6 mile country lane journeys it did. Was only when i took it out on the A road and was consistently at near flat out it seems to have gone wrong. This is what makes me think I burst something.

Will try the above - any other suggestions however simple please let me know. Tks.