Smoking

[kevin s]

Looking if anyone has a any thoughts on an issue with our minor.

It's a rebuilt 1098 engine, with new A+valve guides and seals on the inlets, exhaust valves recut seats, and a fast road kent cam. Drives very well with no smoke when driving (I followed it) but leave it idling and it begins to smoke, drive away and it clears. Obvious thoughts are valve guides, I had acquick look when we adjusted the tappets, the only thing I noticed is the spring seems pretty compressred.

rps20220701_152028.jpg (125.3 KiB) Viewed 1584 times

It seems to have got worse since we adjusted the clearances (all were quite loose).

I'm wondering if the bottom of the valve spring cap could be hitting the top of the A+stem. Seal, anyone heard of this before? Any other ideas?


When I have some more time I will try to measure it and check the seals are all there and not damaged.

[Sleeper]

Where is your breather routed to , the carb?

John.

[kevin s]

It goes into the back of the standard 1098 air cleaner and I can easily blow through it into the crankcase, A carb and exhaust uprate is on the cards but I'd like to get it running perfectly before we go there. It idles perfectly with np suggestion of plugs fouling, is it possible that it's being pulled down into the (gas flowed) exhaust ports?

[Sleeper]

Just a thought, when idling there will be little vacuum pulling any crankcase pressure , will this vacuum increase with engine revs ?

John ;-)

[kevin s]

It has the type of breather that pushes from the crankcase through a can then into the air cleaner.

New unrelated problem now though, it's my son's car and he is using it while we are on holiday, he's been using it for 2 years now with no problems but now it's suffering from fuel starvation ( idles fine but after a few minutes driving starts splutterung, stop with it idling for a few minutes and it is fine for another mile or so, apparantly you can drive at about 20mph ok). Only reason we can think why now is he had to put a tank of E10 in a week ago and it's damaged something in the tank pump or filter king, not the end of the world and shouldn't be difficult to find what's wrong though.

[James k]

I think that type of breather should be connected directly to the carb, not the air filter. That's where it is on mine.

[oliver90owner]

My thoughts?

What colour smoke? Guessing it is blue.

It would need a fair amount of positive crank case pressure to get oil down the exhaust guides - readily checked by removal of oil filler cap at tick-over.

Most likely is the very good vacuum, with the carb throttle plate closed, in the inlet manifold drawing oil into the inlet side. As (to be checked) the valve stem seals are not working, or the guides have too much clearance.

A few thou of an inch clearance change should not make a deal of difference, but will only increase the valve lift.

[kevin s]

It's blue and smells like oil burning, I think I will buy 8 new stem seals, and replace them all checking clearances and inspecting the old ones as I go, guides are all new and I couldn't feel any play in them,.

I've got a tool I used to use on ford engines somewhere which hooked under a spare rocker shaft with the rockers removed (have several of these) with a bit of soft rope in the plug hole you could do all 8 stem seals n 20 minutes or so.

[les]

I’m under the impression that the exhaust valve guides should not have seals fitted.

[kevin s]

Seems to be a area wven BL couldn't make their mind up on, some had 4 but later on they apparantly fitted 8 of the viton ones, I'll go this route.

[philthehill]

It is better if top hat seals are only fitted to the inlet valve guides.
Unleaded fuel can be considered to have little if any lubricating qualities - therefore the exhaust valve stems and valve guides need all the lubricant they can get otherwise there is the possibility of the valve stem picking up in the guide.
If top hat seals are to be fitted the correct valve guides must be used. Both small block and large block valve guides with the top hat location groove are available from ESM.
The correct valve guide for the head must be set at the correct height above the valve spring seat otherwise the top hat seal may foul the valve spring top cap.
When the valve guides have been fitted the correct size reamer should be run through the guide to ensure the correct clearance between valve stem and guide. Also when new guides have been fitted the valve seat should be cut to the new valve guide otherwise there is the possibility of poor valve to seat contact.
When BL could not make up their minds as to using 0, 4 or 8 valve stem seals unleaded fuel as we now use was not around - the valves and valve stems were lubricated by tetraethyl lead. It is the use of unleaded fuel that should determine as to whether valve stem seals are used or not.
The original 'O' ring seals are not worth fitting as they become useless very quickly.

[oliver90owner]

Back in about ’71/72, I recall a head (I had work done on) gave trouble with a sticking exhaust valve. The fellow had reamed the valve guides, recut valve seats, tidied up the gas flow through the head and removed several thous from the head face (more than enough to require rocker shaft pedestal spacers).

The new valves, or his reamer, resulted in the clearances being a bit on the tight size, and the engine went on 3 cylinders once run a bit energetically. Cast iron guides, of course.

Ford supplied valve stem seals for all 8 valves in the head gasket sets of the day. Removal of the seal on the offending valve stem (and likely the other exhaust valve seals as well) solved the slight glitch on that engine, so I have never used seals on exhaust valve stems since.

Maybe BL changed the guide material when they changed the exhaust vale stem seal requirement? Like PTH says, I would never even contemplate changing guides without recutting the valve seats, for concentricity. Doing half the job is not the way to go.

[philthehill]

Thanks to Les I have the correct size reamer 9/32" which was part of a batch of small reamers I purchased from him.
Having a little slack in the valve guide is better than having the valve a close fit in the guide.

[kevin s]

Valve seats were re-cut by the place that fitted the guides.(exhaust had unleaed seats and new valves too). All we really did is an attempt at gas flowing as per vizard and assemble it.

It runs superbly, and has done long trips towimg so I don't think there is any problem with valves sticking, it's done the smoking since the day it was built though.

I Think I need to pop a couple of springs make some measuements on the guide protrusion/ spring cap clearance, check I have fitted the seals on the right valves and go from there.

[mowogg]

Have you changed the breathing as suggested above. The can breathing system was only fitted directly to the carb inlet or pcv valve. You have a non standard set up.

What cap do you have on the rocker cover? Breathing of closed

[kevin s]

This is the breather set up, as far as I can see threre is nowhere on the carb to put it, the rocker cover cap has a breather hole in it.

rps20220709_081329.jpg (21.06 KiB) Viewed 1278 times

[mowogg]

This is not correct. The breather should be connected to an intake on the carb on the bulkhead side. I suspect you have a different carb fitted.


If would be worth changing the engine breather to an earlier type and vent to atmospheres. You could change the carb but it would be easier to do the engine breather

[kevin s]

Quite possible it was a mixture of 948 and 1098 parts when we bought it, eventual plan is twin carbs and a PCV system, as it is it vents into the air ceaner case so effectively to atmosphere.

[Sleeper]

" Where is your breather routed to , the carb ? "

" It goes into the back of the standard 1098 air cleaner and I can easily blow through it into the crankcase "

So it's not blocked.

" Just a thought, when idling there will be little vacuum pulling any crankcase pressure "

On the filter side of the carb...

" I think that type of breather should be connected directly to the carb, not the air filter. "

" Most likely is the very good vacuum, with the carb throttle plate closed, in the inlet manifold drawing oil into the inlet side "

On the filter side of the carb ?

" Have you changed the breathing as suggested above. "

John ;-)

[philthehill]

Whilst the system may be non standard - if you google images of Morris Minor engine bays the set up that is fitted to Kevin's Minor is quite common.
I would be tempted to leave well alone and at a future date fit the twin carbs with a PCV valve. Make sure that the PCV valve used is the latest type as the earlier type with the diaphragm vulcanised to the valve disc is no longer available and/or parts discontinued.