Classic A-Series running issue

[itcaptainslow]

I should probably start by saying the running issue is it basically won't

Some of you may know I've got a 1980 Austin Metro 998. It was running delightfully until I took it off the road over winter to remove the engine, tidy it up by painting it, attend to a few oil leaks and get the cylinder head refurbished and converted to unleaded.

All went back together swimmingly and I tried to start it. The car struggled into life, backfiring through the carb and spitting fuel out of the same orifice like no tomorrow. It seems to be massively overfuelling - the tops of pistons 2 & 3 especially are soaking wet, and the plugs come out drenched in fuel.

Fast forward through the following checks;

- Valve clearances - all perfect at 12thou when cold, and I've rechecked them twice since setting them.
- I can barely get it to run but when it does, I've set the ignition timing to the book (15 degrees BTDC at 1,500 rpm with the vacuum advance disconnected), adjusting this doesn't really make much difference.
- Compressions are all spot on at 180psi across all four cylinders.
- Camshaft timing wasn't disturbed during the refurbishment work (I masked off the crank pulley etc).
- Carb was rebuilt when the car was restored - I've checked the float shuts off the fuel supply by doing the "blow" test with the carb removed.
- Tried adjusting the fuelling using a Colourtune as a reference, little joy here.
- Renewed the crankcase breather pipe.
- It's got a brand new distributor, coil & leads, but behaves exactly the same with the old stuff fitted.
- Carb dashpot is full of 20w50 oil.

The manifold was refitted (as was the carb) using all new gaskets, and I've had it all apart and renewed the gaskets again, just in case. The manifold mating faces are all clean and straight (checked with a straight edge), as is the cylinder head.

I'm suspecting some kind of carb fault causing it to dump loads of fuel into the cylinders uncontrollably, but I'm stumped from here being honest - I was raised on electronic fuel injection!

Any suggestions or ideas would be appreciated.

Edited by itcaptainslow on Thursday 25th June 19:08

[finlo]

Distributer out 180°

[itcaptainslow]

finlo said:

Distributer out 180°

Didn't realise you could fit it 180 degrees out...that's worth a check, thanks!

[hidetheelephants]

Modern fuel is toxic rubbish that evaporates and turns into glue, there's a decent chance something's gone wrong in the carb, although there may well be some other confounding problem. The perils of fixing things that aren't broken, should have just left it alone.

Edited by hidetheelephants on Thursday 25th June 20:24

[itcaptainslow]

hidetheelephants said:

Modern fuel is toxic rubbish that evaporates and turns into glue, there's a decent chance something's gone wrong in the carb, although there may well be some other confounding problem. The perils of fixing things that aren't broken, should have just left it alone.

Edited by hidetheelephants on Thursday 25th June 20:24

You're telling me! Regretting pulling the thing apart...! The fuel has been in the car since last autumn, so again I'm suspecting it's perhaps a stuck fuel needle or perished seal thanks to the horrible ethanol. I've also got a horrible feeling the carb was stored on its side, rather than up the way it should be, mimicking how it's mounted on the car.

Regarding the distributor being 180 degrees out, I should add I did have it running (ish) on a fast idle, and initially set the ignition timing by getting the engine to TDC and the rotor arm pointing to number 1 contact point (which looking at the distributor front on is the rotor arm around 10 o'clock).

[njw1]

I'm not too familiar with those engines but does the carb have a fuel return line? If yes, and this is probably a silly question, are the feed and return lines on the carb the right way around?

[itcaptainslow]

njw1 said:

I'm not too familiar with those engines but does the carb have a fuel return line? If yes, and this is probably a silly question, are the feed and return lines on the carb the right way around?

It's got a fuel drain rather than return, and can confirm they're on the right way around - already checked against the "before it was pulled apart" pictures.

[itcaptainslow]

I think I may have hit upon my mistake, thinking back through what I ve done in the rebuild process. I assumed the distributor ran clockwise, and didn’t check it.

I’ve just checked it. It runs anti clockwise.

I’ll let you know how it runs tomorrow when I have got the carb back on.

[hidetheelephants]

As the carb was rebuilt and you had it running before it may just be fuel gunk blocking a passage way or jet, stripping and attacking it with a can of carb cleaner may be enough to get you going again.

[ARH]

When I read the first post, my gut said firing order straight away. So you could be right. I have covered 100's of thousands of miles on A series engines over the years. Not much I haven't had to fix.

A few things to check, do they still use waxstat jets when rebuilding carbs?

Most rotor arms are rubbish, as are condensers if it still has these swap to something electronic, or at least check out some mini specialists for prats.

[itcaptainslow]

It’s got electronic ignition already fortunately. I’m very much hoping it is the above, even if it does make me look a prat!

[bangerhoarder]

First instinct was distributor 180 degrees out. Done it on a B Series, and it behaved identically to yours!

[littleredrooster]

Plug leads in the wrong order would be my best guess if you set the rotor arm to point to no. 1 cylinder at TDC compression (it was on compression, wasn't it?)

[redbulletv8]

Check firing order and check you have the leads on cap to suit rotation, (swap 2 & 3 if not certain).

[ARH]

itcaptainslow said:

It s got electronic ignition already fortunately. I m very much hoping it is the above, even if it does make me look a prat!

Don't worry the reason we are all saying firing order is we have all done it.

I once spent a hours trying to get fuel to a mini carb with no luck. My mate came round and tapped the fuel gauge it went to zero, a stuck fuel gauge didn't even cross my mind. It sooned worked with fuel in the tank.

[littleredrooster]

bangerhoarder said:

First instinct was distributor 180 degrees out. Done it on a B Series, and it behaved identically to yours!

I think the drive key is offset to prevent this on this era of the A-series.

[itcaptainslow]

It was me being a tit and presuming the distributor ran clockwise. Refitted the leads appropriate to anti-clock, it fired up perfectly, had a little splutter to clear the fuel and ran away merrily.

I’ve set the ignition timing, fuelling and idle and it now is back to its prior ways of setting the road alight with 42bhp(ish).

Thanks to all for their input - the poster who said “Distributor 180 degrees out” got the cogs turning, as it then made me realise the firing order could be wrong, as 2 & 3 were the soaking wet ones!

[hidetheelephants]

Excellent! Frustrating when you're the architect of your own misfortune, but no damage other than to your pride. Been there too many times myself.