Silver Shadow 1 non-ignition

[adamski46]

In the process of making my father's '72 Shadow roadworthy. Have carried out the following - Rebuilt and syncroed carbs (new jets and new needle valves adjusted), rebuilt fuel pump, installed powerspark ignition, new plugs, new leads, new coil. timing set to between 5 and 10 BTDC (makes no difference to the problem I have). Choke cleaned out and seems to be working fine - is fully opening when car is warm. Carbs reasonably balanced and mixture roughly set on both - down about 2 turns. Airfilter is clean.

The problem - plumes of white smoke from the exhaust, which does not seem to be a rich mixture problem but unignited mixture being kicked out through the exhaust.

As far as I can see there is a spark at each plug - shadows are a bit tricky to get in to see all the plugs

The engine is missing on at least one cylinder because there is definitely 'lumpiness' on acceleration. Plug at B1 is wet when I took it out, all the other plugs at least look like they are firing

It could be something 'tricky' like a stuck valve - have put some Wynn's in the oil to see if that helps, but I cannot stop thinking that I am overlooking something relatively simple.

Engine is original with 22k on it. Has not been run for about 12 years, and not so much before that.

This is likely to drive me bonkers, so happy for any suggestions. Cannot get her MOTd as she will smoke out the garage..

[TerryG]

Are you losing water? white smoke to me says blown head gasket. If you are worried about a sticking valve have you done a compression test?

[adamski46]

Thanks. Water level is not dropping and smoke has a petrol, not antifreeze smell. Compression test was suggested elsewhere and is next thing on the list.

[JPB]

Is the hydraulic fluid level dropping? White smoke can be a sign of a leak from the back of the brake master cylinder into the servo on a car with a conventional, inline servo and cylinder but perhaps there's some way in which the accumulator on these can leak to the inlet manifold?

And if the issue is a sticking valve, then adding stuff to the oil won't help so much as adding a suitable UCL (2 stroke oil, Redex, brake fluid, etc.) to the fuel. Add a teaspoonful directly into the affected cylinder too, that'll make even more white somke but will soon get a sticking valve moving, especially if the car is taken for a damned good thrashing.

[zipgun]

he means a spirited drive

[adamski46]

Thanks all.

Hydraulic fluid level is fine. I went out this morning and noticed a couple of things - peculiar how writing down a problem makes you focus on it...

1. There is soot around the carb piston = ignition in the carb chamber. Have cleaned up and will check again tonight to see if that has gone away. I had not seen that before, but that is symptomatic of a stuck inlet valve - maybe the Wynn's will help. Picking up a compression tester today and shall check those tonight.

2. The floor of the carb around the jet is soaked with petrol, even after standing overnight. I have checked and rechecked the float chamber settings, but I have noticed that the needle end nearest the piston is pitted, which would lead to excessive flow of fuel. Will replace on both carbs.

onwards and upwards...

[adamski46]

cracked it. Bent pushrod on number 1 inlet valve. Tedious, but could be worse.

[Luxobarge]

cracked it. Bent pushrod on number 1 inlet valve. Tedious, but could be worse.

Well done and thanks for letting us know.

The immediate thought that comes to mind is - why? Do you have any idea how it became bent? Wouldn't happen in the normal run of things....

Cheers!

[JPB]

Wouldn't happen in the normal run of things....

Oddly enough; it's pretty common among some more prosaic engines including the 1200cc ancestor of the B series, as found in various of the "Counties" Austins. Also, when they first set up in the UK, FSO dealerships all made sure to have at least one pushrod straightening specialist in their workshops as the 1300 and 1500cc engines in the 125P suffered from this phenomenon. Though they would happily run like this and rectification was an item on the major service schedule at 12000 miles or more frequently as required.
I'm surprised that the mighty Rolls-Royce/Bentley L series suffers this way though, they have a reputation for being strong enough.
Mind you, some folk claimed that [the L series] was a recycled GM product and that wasn't true either so who knows..

[adamski46]

I am going to strip it down this weekend. The engine was hardly run for about 10 years, so my guess is:

1. either the pushrod got stuck and when the car was started it stayed stuck, or

2. the hydraulic tappet failed.

possibly a combination of the 2.

Shall report back with some pics in due course.