The All New, New "What have you done to your Bay today" thread.

Get 'em on!

 

Probably yes.

Todays effort uncovered the source of " blowing oil out the back and it runs a bit rough" ..



Found a few random small bits of foam under the tin all about 20mm across. Nothing major.

And one of the heads had a crack in the sparkplug threads going right through to the outside- you could see black marks where it had started leaking.

So I ordered a set of four 1641cc AA pistons and cylinders to match whats on there at the moment, and because they were in stock at Heritage.

And an EMPI 040 head, the last one in stock..

And yet another bag of seals and gaskets.

I dont think theres any big chunks of metal in the engine as they could only come via the oil control ring and the piston is just melted on one edge.
I couldnt find any metal in the oil pump, only a few flakes under the strainer and what came out of the full flow filter and sump looked just a bit glittery.

As I think I am more likely to mess up splitting the case I will go for a few rapid oil changes.


Spent the rest of the day tidying up the tinware , cleaning aluminium flakes off the good head ( which had the melted piston under it.)

 

Ouch!
So, the question is - what caused it? You know you need to work that out or it might happen again on you next drive with all those new goodies. Loose inlet manifold?

 

But it`s a 1641 , that`s plenty enough for any man ...

 

The rear cylinders do run a little leaner on normal days, going by plug colour.

Standard distribution of mixture for not having FI or 4 carburettor barrels..

But when I looked at the plugs the other 3 were pretty identical, light brown, no deposits.

The other pistons have an even coating of carbon, no "softened" edges or signs of metal flakes. And compression as new.

The manifold was tight and the manifold boot was tight ( Will look for split tomorrow) The plug lead turned out to have a slightly loose end.. and the crimp pulled off easily.. maybe misfiring or losing spark energy sometimes as a result.

The distributor I was using was my number 3 ..

1. Bosch with Accuspark electronic module that failed back in 2021, kept for analysis.
2. Moved to a Bosch with points for a year .. but that went wrong on the way back from TE this September.
3. Fitted Accuspark cheapie Chinese points distributor .. this timed OK at 8 TDC idle, but the max advance check was done years back with an adjustable timing light that turns out to be under reading over around 8 degrees. But generally that distributor would have been used at TE to start engines and then put away.
Except on Wednesday.

Looking back the effect was that because it was over advancing I was backing off the throttle, the "power valve" wasnt cutting in so it went back to about 14.5:1 AFR , when normally I would have been putting pedal closer to the floor at around 60-65 mph and getting power valve operation, 11.5-12.5:1 AFR and seeing temperatures stay steadier.

"Normally" it only leans out rolling down steepish hills on the motorway at 60-65mph, the rest of the time it runs richer..

 

So... the over advancing thing is conjecture really. How do you explain the other cylinders looking fine?
I get than one will let go first, but to me it seems like it's been running under very different conditions than the other 3.
So, yeah, out of all your theories above I'd go with unburnt fuel from poor spark pre-igniting on the compression stroke... i.e. the dodgy HT lead.
But I'm not expert at this sort of diagnosis. Did you hear it pinking? I only here pinking with the window open and it's not "real" pre-ignition, it's just slightly advanced normal ignition. Proper pre-ignition is (apparently) much more severe, I think you'd have heard it/felt it.

 

Believe me , you`ll not hear anything untoward at 75mph in a 1600/41 ....

 

today i laughed and smiled at the bus i now own

400 miles around wales and back home this weekend...

Sent from my ELE-L09 using Tapatalk

 

Shifted back to installing the electrics for the heated windscreen as I await the expensive parcel from Heritage.

Had a bit of a panic.. wired up to the spades on the screen. Measured DC resistance to chassis using a digital volt meter and got 24 ohms on the left side area and 11 ohms on the right.
Which is not anything like the nominal 0.99 ohms...
Noticed that when the sun warmed it up the resistance seemed to drop a couple of ohms, so I decided to whack it with 12 volts, so I ran the end of the wire to the leisure battery positive and dabbed it onto the wire tail I had made up.

It went sparky, much more than about 1 amp would do, so I did the same the other side .. also sparky.. and the resistance is now about 1 ohm both sides.

So its worth continuing.

 

Painted @Lasty 's bits.

 

They're very spangly

 

Are they golden?

 

Definitely golden then, very fetching

 

You ask first

 

You'll have to wait till next month's GQ magazine comes out...