project 1980 Austin Princess

[vulgalour]

There's a flap on the air intake that's supposed to automatically decide to be open or shut, the foam that seals it has long since dessicated, so I imagine that won't be helping matters.  It works much like a bimetallic relay, just larger.

[PhilA]

Those little vacuum motors tend to be moderately reliable, and some foam padding missing won't have much of an effect (probably find it's there to stop the flap vibrating).

 

I found timing being a bit off and the intake temperature getting stuck on hot caused some unreliable engine characteristics. The valve that opens to control the flap motor had failed, in my case.

 

Phil

[vulgalour]

If you go around a left hand bend quick enough, the flap does go ting-ting-ting-ting.  There's no vacuum motor or valve, it seems to be purely heat-powered.  The air box has a spout inside of which is the flap.  There's two outlets on the flap, one goes to a box around the exhaust manifold, the other goes to the fresh/cold air intake.  I suppose I could just disconnect the cold air intake pipe to reduce just how much cold air is getting fed to the air box and see if that improves matters, or cable tie some cardboard to the grille as a rudimentary muff.

[dollywobbler]

To think - everyone is taking their hat's off to you, and they probably haven't driven it! I have, so my hat is exceedingly well doffed in your direction. Very doffed indeed.

[vulgalour]

Well... when you drove it the poor thing got a bit of stage fright, it's better now.  Mostly.

[PhilA]

Aha, strange contraption then. Very BL.

 

I think you're in the correct direction though. Check the timing etc.

 

 

Phil

[timolloyd]

Sometimes I wonder how much things like misfires at cold are actually normal, except we've forgotten what its like to have ‘normal’ cars and are too used to the consistency of fuel injection

[PhilA]

Pop snap cough back through the carb is normal enough for a cold engine in a cold environment.

 

However, some are more prone to it due to wear or age.

 

I believe that is "character", and can usually be adjusted out though.

 

Phil

[vulgalour]

If it were a more regular occurance, this occasional misfire-when-cold thing would bother me but I think it is more a character thing, like you both suggest.  I do think this is what I missed with the Rover, its reliability and ability to iron out these idiosyncracies one of it's greatest features and yet also its greatest flaw for me as an owner.  I prefer a vehicle that feels.. well, not alive, but as though it's mine.  The sort of car where I know how to drive it, and which of its little noises and quirks are fine and which are to be worried about.  Anyone can get in my Rover and drive it, piece of piss, Princess not so much.  You've got to be a particular sort of person to be able to drive the Princess, and indeed to want to, and that's the way I like it.

[Noel Tidybeard]

i don't even think its a misfire more of a cold cough- my mini only needed 1/2 a choke to start and then about 1/4 for a while the it would run pretty well with only an occasional "primus pump" of choke for harder acceleration untill fully warm

[vulgalour]

That's pretty much exactly it.  A case of TADTS, most likely.

 

I'm sticking to a weekly check regime, and it being Sunday that marks the end of Week 2.

 

Coolant - no apparent loss

Oil - no apparent loss

Wheel arches hosed out, bottom half of car hosed down, including sills and under the front and rear valance.

Corrosion check - no noticeable advancement except for one area.  On hosing out the rear inner arches it looks like at some point this week I lost a chunk of old underseal and it's revealed some rust I was unaware of.

 

 

The upper circle marks where there's a small hole and some heavy pitting.  The lower circle isn't crumbly, but does look like it might be flakey rust or a crack.  Thankfully the area is easy to access and repair.  I should be able to repair this area without disabling the car for more than a few hours so when I get the next opportunity to do so I will clean this up and sort it out.  I'll also clean all the old underseal out of this inner arch and redo it.  Once I know it's solid, I'll do the other side too and that should see us good for a while longer.

[SiC]

Is there a bit of surface rust to the right of the lower circle?

[vulgalour]

There is, I gave it a stabby-scrape with the screwdriver and it's very minor surface corrosion.  Nothing is crunchy, thankfully, it seems to be fairly localised corrosion so shouldn't be too difficult to deal with.  With the rear wheel removed I should have lots of space to do the repair somewhat comfortably.  Of course, I won't know how good or bad it really is until I get in there with power tools and cleaners, so here's hoping it's not an iceberg tip.

[vulgalour]

Today I got the Princess over to the unit so I could fix the inner arch holes I uncovered.  I also removed the cold air intake pipe to the air filter box and that improved the cold running considerably.  It took me longer to clean off the underseal than it did to do the actual repair.  Happily, the damage wasn't much worse than what was visible and was an easy fix as a result.

 

 

With the rear seat removed it was easier to see just how the rust had occured.  There's a seam hidden under some goop under the rear seat and this had blown.  The inner arch side of it was rotten, the bodyshell side was still solid enough to weld to, so the repair wasn't too bad.

 

I also found a small hole on the seam of the inner arch tub while cleaning off the underseal.  It's a little awkward to repair since I can't get many tools in at it and will require a patch about the size of a pound coin.

 

After a little bit of time I got some new steel let in where required and seam welded.

 

 

Since I'm still running the experiment, I'm avoiding taking the car off the road and doing these repairs piecemeal.  The bulk of the time today was really stripping everything back to see what I had to repair.  Now that I've done that, getting everything cleaned back and freshly painted and undersealed will be much easier and something I shall be making time to do over the course of this week.

[320touring]

Tremendous! #drivethruwelding

[Uncle Jimmy]

Yes, they are that wide and parking spaces don't seem to have been changed since the 1990s.

More likely the 1950s, based on the width of a Bond Minicar and two trilby hats.

[vulgalour]

End of week report: Week 3

 

Weekly checks:

Coolant - no noticeable usage

Oil - no noticeable usage

Fuel filter - New one fitted today as the old one was looking grotty

 

It hasn't been a good week though.  The mystery misfire/stumble has been getting worse and I'm no closer to finding the cause.  I had thought it was fuel related since the fuel mixture screw has taken to unscrewing itself and, once reset, the problem seemed to go away.  Then it reappeared and became worse.  Today, I reset the mixture screw again, just in case, and replaced the fuel filter since it was behaving slightly like it did when the previous filter collapsed.  I also checked the points gap, which was a little large, and went for a drive.  It seemed much better until the car got up to temperature and then I struggled to get above 30mph.  Another go through the various settings to make sure everything was where it was and on my last run I was struggling to get over 20mph.

 

I'm baffled at this point.

 

When cold, the car fires up normally with choke, as you'd expect.  It runs moderately well with the occasional cough if the choke isn't just so.  Once up to temperature with the choke off the car will run fairly happily for about a mile or so and, as it get closer to full operating temperature, the problems really begin.  If you're really slow on the throttle you can creep the speed up but if for any reason you need faster acceleration or prolonged throttle usage - pulling out of junctions, climbing hills, etc. - the misfire/cough gets worse and worse, the car begins to kangaroo and the only way to resolve it is to back off the throttle and gently creep it up.

 

Once up to full operating temperature even creeping the throttle won't let you accelerate much.  It's like something somewhere is restricted once the car warms up.  This isn't a problem its manifested in this way before.  Monday, therefore, Mike and I will go through the timing, the ignition components, the fuel delivery, and see if we can locate the problem.  Fortunately my spare carburettor is with a skilled friend who is currently doing a top notch job on making it like new again and I hope a freshly rebuilt carburettor will help with some of these problems.  I had hoped to drive over to see him and fit it at his place, but I can't imagine the car will be any fun to drive for two and a half hours running like it is at the moment.

 

At the moment this doesn't end the experiment.  The car hasn't left me stranded and has always got me where I need to go.  However, if I can't resolve this problem promptly the experiment will have to be restarted.  At present I regard this more as a general problem, as can afflict any car of any age at any point.  Until I know more about what the problem is, I'm not prepared to bring the experiment to an end.

 

Here's a nice picture of the Princess a few days ago, when it was running much better.

 

 

[Rocket88]

Are you running a mechanical or an electric fuel pump.....

[vulgalour]

In-tank electric and, as far as I can tell, it is doing its job as it should.

[Rocket88]

Have you tried pulling the choke out when it starts to stumble..........

[captain_70s]

Sounds a lot like what the Doloshite was doing when that was up to temp.

 

I'd like to say I know exactly what caused it but I don't. I just fucked around with the ignition system and carb until the problem was lessened... What carbs do these have, waxstat SUs?

[vulgalour]

Colc: I have, and it makes things *lots* worse.

 

Cap'n: SU HIF6.  Let's hope it doesn't do a total Doloshite on me.

[Rocket88]

In that case........possibly running rich...............try leaning it off a little......

[vulgalour]

An small victory!  Glen over on another forum suggested it might be a blocked fuel jet so recommended pulling the air box off, covering the air intake with a hand while revving the engine.  The vacuum should then suck whatever's stuck in the jet, out of it.

 

Gave it a try and the running is improved, I can now put my foot down and it will actually go.  I'll take the carb apart and clean out the jet and that may well fix the issue completely.

[PhilA]

Does this design of carburetor have an emulsion tube on the pickup of the main jet?

 

Sounds like you may have drawn some grubby water though at some point, perhaps some refinery sand particles that are finer than the filter.

 

Reason I ask is you almost need to run a stone filter with emulsion tube jets, the holes are so fine.

 

Hopefully that's just it and you get to enjoy driving it again. Things like this are sent to test us, I'm told.

 

Phil

[vulgalour]

There's no emulsion tube on this carb.  I'm wondering if I've just left the old filter a tiny bit too long (not that it's lasted that long anyway) and it's started to degrade, pulling stuff in where it shouldn't be.  The last filter just collapsed and went to mush inside so it could even be bits from that one were floating around in the carb and have only now got themselves where they shouldn't be.

[PhilA]

That's a possibility. Particularly if something in the fuel (some gas pump additive) has caused the paper filter to fall to bits and start sending paper fibers towards the carburetor.

 

I don't think the flow would be high enough for a centrifugal filter, though would a fine metal mesh be enough to trap particles big enough to block up holes?

 

Phil

[vulgalour]

Like a post-filter filter so I can filter my filter with my filter to stop my filter getting into the carb?

[vulgalour]

Filter.

[PhilA]

Quite possibly.

 

 

Phil