Hi i am new to austin 7's my 1935 ruby special appeared to have oil in no 1 and 2 cylinder so we removed the head tonight to check the bores and pistons, the bores look good as do the pistons, they is a bit of movement on the pistons

They are standard sized pistons, at what amount of wear do i need to get a re bore done.

Location: Suffolk

Hello Leon, with standard Austin 7 pistons it is usual to see some evidence of oil in all cylinders; be aware that, when new, The Austin Motor company quoted an expected oil consumption of 1 GALLON per 1200 miles i.e. 1 pint every 150 miles (and that was without taking account of leakage). Personally, unless the oil ingress is such that it is fouling the plugs to the point of misfire, I wouldn't worry about a rebore yet.
However, if you are running with Honda or Renault 4 pistons, that is a different story.

What oil are you running it on??

Ian Mc.

Location: Shropshire

Ian

Not sure of oil type as we only picked the car up on Good Friday and we only managed to drive about 35 miles with 6 break downs and then had to call out the recovery, after draining the tank and removing lots of rust we got it running but after about 10 mins of idling we had oil being pushed out of plug 1 and 2 and lost a good about of oil from between block and crank case. Our first thought was that it was pressurising the crank case, which is why we removed the head.

Pistons have got STD ID12 stamped on them, can we getaway with just new rings.

Location: Suffolk

Obviously, the 6 breakdowns due to crud in the fuel supply is a separate issue. I am concerned when you say "we had oil being pushed out of plug 1 and 2" as the plugs should seal to the cylinder head and under no circumstances should it be possible for oil to be "pushed out".
Loosing oil from the crankcase/block joint isn't unusual, how serious it is depends on the volume of oil being lost in this way. (something of a design weakness mating an ali crankcase to a cast iron block, given the different rates of expansion of the two materials)

To be honest, it is difficult offer much meaningful advice without personal sight of the car and its condition.
Worst case scenario, a complete engine re-build might be in order, but it would be wise to seek out and join your local club/group and let locals experienced in A7 mechanics give you their opinion having experienced your problems first hand. There are regular forum contributors in your county.

Do you know how long it is since your newly acquired vehicle was in "regular use" ???

Ian Mc.

Location: Shropshire

hi the ring gap tolerance is o.003-0.006 in.but the best indication is how deep the ridge is just where top ring stops.there has to be some play to allow for expansion when hot.I would suggest you remove engine and check all components as you have started stripping it.rings are not expensive and its a nice exercise to get to know your engine,and fun too!my pistons wallop about in bores and am jealous that you still have standard pistons.I replaced my valve seals and valves at the same time as the rings.my problem was after engine breaking on a long hill I had some serious blue smoke once i did accelerate.

Location: germany

You obviously have a number of other issues to deal with, but I have found A7 engines very tolerant of bore wear. I have sucessfully got away with putting together several hack engines by simply honing, often quite badly worn bores then fitting new rings. Results have been suprisingly good and reasonably long lived.

Location: New Zealand

Ian, James and Ian

Thanks for the information.

I was a surprised to see we still had standard pistons, i expected to see at least +40 fitted. Their is no lip at tops of bores,

Location: Suffolk

Hi, I think I should try to clarify the situation. The Ruby engine smoked quite a lot (I Know, I was following) and was clearly pressurizing the crankcase also there was a significant amount of oil loss, we assume this was from the joint between the crankcase and block. However the situation is not as clear cut as it might have been, the engine filler is a home made device that does not fit so to get the car home we put a plastic bag over it and that prevented the crankcase from breathing to make matters worse the tappet chest cover has been made from a flat plate and has no holes in it so again no breathing. Once we got it home we removed the plugs, no 2,3,and 4 all looked ok with only no 1 looking oily and after cleaning the tank out we ran it again for a while without the plastic bag on the oil filler but with the unvented tappet chest cover, removing the plugs for a 2nd inspection showed that no 1 and 2 were now very oily so we decided to pull the head to investigate, the bore look very good but there was a lot of oil in the crown of no1.
So here are our questions.
1) Do Austin 7's chuff a lot from the crankcase filler?
2) Would blocking the tappet chest cover vent holes make a drastic difference to the crankcase pressure?
3) How much bore wear can a std set of rings compensate for?

Thanks to James for putting the numbers up, did replacing the valve seals (guides? does an Austin 7 have seals?) sort the smoking issue?
At the moment the pistons are still in the block so we can not measure the gap and we don't have any rings, if we can borrow a dial gauge we can measure the bores and go from there.

Ian, I think the 7 was last in regular use when it was still a ruby, so 1950?
From what you have posted about wear I am hopeful we can get away with just a set of standard rings.

I must admit that I have always changed all the oils on buying another car to ensure that the correct ones are used.
The lack of oil cap would worry me because of allowing dirt to get in.
The problem with old engines is that you don't know what you have without a stripdown. My Chummy used to smoke quite a bit and it turned out that someone had fitted the wrong piston rings.
Please keep us informed as to progress.

Location: Near M1 Jtn 28

Some may well disagree with this!

As the engine has been layed up for so long my guess is sticking piston rings. from your description it doesn't sound like bore wear to me.

If it was my engine, I would:

While the head is off, put the engine at 90 degrees to tdc and pour a little diesel in each bore, then leave for a few hours. Turn it over on the handle, but do not start it!

Now do the same with a drop of engine oil and turn over a couple of times to relubricate the bores.

Put the head back on.

Change the oil.

Drill some holes in the breather plate you have.

Drill a small hole or two in the side of the home made oil filler cap.

Put it back together and give it a good run, get things nice and warm.

This may free the rings. If not you haven't spent a fortune on rebuilding the engine, if it does, happy days!

Stuart.

Edit. Plus Gas will work if you don't have Diesel handy.

Yes Austin Seven engines do tend to breath quite heavily, but it will be much worse with sticking rings.

Leon, depending on whereabouts you are in Suffolk, the Suffolk 'branch' of the Essex A7 Club meet at the Greyhound in Ixworth every first Monday of the month. Or, the Norfolk A7 Club meet on the 3rd Tuesday at the Jubilee Hall in East Tuddenham, Norfolk. Email me if you want further details.

Location: Farnham and sometimes Suffolk

Leon

As Dave said above, but the Suffolk Branch meet on the first Wednasday of the month.

I live near Bury, if you want to borrow a filler tube and cap, plus a valve chest cover, email mail me.

Mel

Location: Suffolk

I made up an alloy plate for the tappet cover and bored it out to take a domestic water plumbing fitting. I then used domestic fittings to make a breather pipe which incorporated a peice of wire scouring pad to act as an oil seperator. This pipe was vented under the car via a flexible rubber pipe.
This was required to remove the fumes from the car which are common with the original design which just vents to atmosphere in the engine bay.
They do breather from here a fair bit when worn, but mine still ran very very well!
For what its worth I also honed and re ringed a block which had fairly worn pistons. The new rings and de glazed surface did make some difference, but it still liked a pint per 100 miles!
I would get it breathing properly before I did anything expensive like a rebuild. Then run it around and see what happens. If you are still not happy then fair enough pull it apart and do it properly with pistons and a rebore as you are only standard at the moment so plenty of meat hopefully left.

Steve

Location: Shropshire

I would put it back together and run it some more, after the diesel treatment.

And drill some holes - 4 off 5mm near the top edge of the valve chest cover.

My car runs very oily. It needs an engine rebuild, which won't happen for a while. It was oiling plugs every 10 miles or so before we left John o'Groats last Easter (2012)and still made it to Lands End in under 24 hours.

I found some "hotter" plugs before we started.

These engines still work despite all sorts of problems. I guess your breakdowns were due to old/dirty fuel.

Run around a bit more, get some driving time in the car before taking it to bits.

Simon

PS It is not uncommon for some oil to work its way out around the plugs, either.

Location: On a hill in Wiltshire

hi yes the valve guides and valves did the trick and also reduced smoke and back pressureYR6T from engine vent.there are no seals.as you say the bores are not that worn i would tend to go for sticking rings like someone else suggested.

Location: germany.

As a general rule you can tell the difference between oil coming up the bores or through the valve guides.

If its the valve guides the smoke will be significantly worse after a period with the throttle closed, such as braking for a corner. When you accelerate away from the corner there will be a big cloud of smoke for a few seconds.

If its the bores then the smoke will be fairly constant with possibly a slight increase after closed throttle running.

Of course with there being no crankcase ventilation on your engine this will tend to force oil out where ever it can be forced, so you may get the symptoms of valve guides even though they are reasonably ok.

Location: Devon

Thanks to everyone who has contributed, bloody brilliant.
Here's the plan as of Yesterday PM.

1) Borrow a dial gauge to measure bores.
2) Regardless of 1 we will remove the sump and drop out the pistons for inspection.
3) if pistons/bores look ok fit new rings and reassemble. If not then it's of to the machine shop for a re-bore.

I think we have now sourced a proper valve chest cover and filler cap.
Who knows may be it will be back together for the Ixworth meet early next month.

I have a theory about the oil on and around the plugs and why it was worse when we left the engine ticking over. I think that no1 cylinder being closest to the rad does not get as hot as no4. On a longish journey on a hot day all cylinders reach a temperature high enough to burn off the oil but not on a cool day.

Awkward

The engine is built more like an old motor cycle, it is in three parts Head, Cylinder Block, and Crankcase.
If engine is in the car, the crankcase can be left in, once the big ends have been undone, then the Cylinder Block can be lifted off with the pistons still inside the Cylinder Block, the floor might have to come out to get to the 2 rear bolts, there is 3 under the valve chest.
I have a book called The Austin Seven Companion, which will help if you want to borrow it.

Mel

Location: Suffolk

Awkward

If you have the oil baffles fitted then you cannot drop the piston assys out the bottom. Yours may have been removed or butchered if it was rebuilt in the past?
You can only get the pistons out the top way if the big end part of the rod has been fettled and you are on a bigger bore size and aforementioned baffles are removed/cut, which may or may not apply to your engine.
The more usual way is as suggested which is to split the block and crankcase joint which potentially is leaking anyway!
When you get to put it back together first spend some time reading about all the weird and wonderfull ways people have found to do it over the years.........

I still think I would get it breathing and use it, like Stuart says.

Best of luck

Steve

Steve

Thanks for the information, i've got a gasket set on the way so if we have to split it its not a great hassle and it will be a good leaning exercise.

And as Awkward said thanks to everyone who contributed, we will let you know how we get on.

Location: Suffolk

I'll be doing the leaning, Leon will be learning.

Leon,
I've been following this thread as I've been going through a very similar experience over the last two weeks. I'd glaze bust and re-ringed the pistons over the winter lifting the block off.

I've had bad crankcase pressurisation right from the first start up. My first run of about 5 miles nearly emptied the deep sump and the mist coming through the floor was almost intoxicating. The engine had a breather as described - small bore plumbing from the tappet chest cover feeding into one of the mesh air cleaners on the SU's but it couldn't cope with the amount coming through.

I read all the generic advice on the interweb about hard acceleration and backing off to get oil and cooling round the bores and thought that even if I hadn't glaze busted very well having a thrash round the countryside was easier than starting all over again (that maybe had the same outcome).

Following some of the ideas in the thread I extended the tappet chest breather down to the brake cross shaft. An extra breather went on the oil filler neck (a donation from the Speedex engine) and one on the blank where the fuel pump normally sits. All extended with another donation from the garden hose to around the cross shaft. I sealed the starting handle.

Off I went this morning and success! No fumes or mist in the living area (I had put the carpets back in which may have helped seal the floor some). It was going well, flying really. There was still some oil coming out of the breathers but the sump level wasn't plummeting. I was feeling really chuffed with myself and considering giving the ignition a tweak and checking the mixture and balance.

Then the head gasket went. Closely followed by a clank from the bottom end.

I know your car is new to you and you're dying to get ripped into it but you may not need to. My engine is a genuine Cambridge built in the 50's. I cleaned out the treackly oil and checked the big ends were OK. It was making compression so I ran it as it was and got 1400 miles from it without anything else until the oil consumption got too bad. And look what's happened since!

My advice would be; if the engine runs leave it alone and spend your time and money on other things - I'm sure there'll be plenty of other bits that need fixing.

Dave

Location: NE, and a bit sad

Gentlemen, get your spanners ready......................wait for it........go!

About 20 mins later......................................................

It's been re-lined back to standard but unfortunately has some pitting in no4.
We are considering our options and will keep you posted.

Early start but it was good to get the block off and see the condition of the bores.

These sevens are very nice to work on

Location: Suffolk

Well guys, I'm not too keen on sleeved A7 blocks and that looks, in the photo, like serious pitting. Do you think you would clear that at +0.060"?? If not, I'd be inclined to look to a different block.

In fact, assuming that it still has a 3 bearing crank, I would be looking for a different engine.

Ian Mc.

Location: Shropshire

It may be cheaper to fit a new liner and bore it to suit the pistons you already have, if they are useable.

The block is stripped and will be dropped off at the Machine shop in the morning for 1 new liner and the other 3 bores will be honed, i'm hoping soon i can start putting bits back on instead off taking them off.

Location: Suffolk

This takes me back a few years. When I first got my car it would tickover but had absolutely no power. It transpired that some one had fitted new standard pistons to a badly worn block. It was so bad I re lined it and kept the standard pistons. I have had no trouble since.

Location: Derby

Well i picked up the block this morning from Scholar Engines, I will grind the valves in on friday and start to rebuild the engine on saturday

I have tried load a photo

Location: Suffolk

Well we have put the engine back together and at had it running by 16.00 and took it for a little spin round the garden by 19.00.

Location: Suffolk

After a good day on Saturday we spent Sunday morning working on the brakes and any other unsatisfactory areas of which there are many, then again on Monday morning re fitting body work and connecting up the rear lights and by the afternoon we were ready for the first drive, Which went very well. The engine is much improved and there is no oil being pushed past any gaskets and no smoke.

Location: Suffolk

I love it when a plan comes together, great news!

Location: Near Bicester and nowhere near Europe

Just a bit of an update



Driving back from the south of France a few weeks ago after about 2 hours of driving there was a deep rummbling so stopped, once off the A71 I phone to arrange recovery which was included with RH insurance.


A week and a bit the car was delivered safe and sound and I was able get the fee I had to pay to get off the motorway reimbursed.

As soon as the car was back I dropped the sump and ordered some new shells, when I went to fit the new ones I noticed a little crack in the crank.

Only one word for that...

"Bugger"

Location: Gard, France 30960

Yikes. I'd like to see what you think a BIG crack is...
Oh dear.

There is a good section on the Speedex site on setting of the centre bearing on 3 bearing engines, and why problems often arise.

JonE

I have read the section on the 3 bearing engines but I think I will save up and build a nice little splash feed 2 bearing engine, as long as I can do a steady 60mph with it that will do me.

Driving down to the south of France we were cruising at 50mph and it's amazing how far you can travel in a day at that speed.

Ruairidh

Nice to hear from you, the CC engine was planned for this journey so I could keep up with Awkward and all fabrication work one machining done well in time.

First long run went really well cruising on the A14 at 70mph and the engine not completely setup. When we got to Southwold for breakfast I check water level in the radiator and there was about 1/4 pint of oil in it. After Awkward pressurised the water jacket and oil ways he found a very small hole or fault in the mail oil gallery, we made up a sleeve and fitted it. At first it seemed to be ok but after a while we had oil in the water.

So 5 days before we were due to leave for France we had not choice but to fit the tired trusty seven engine.

Day 1
A12, M25, M2 to Dover


Day 2

N154 Evreux, Druex, Chartres, Orleans then A20 to Brive-la-Graillarde 2nd overnight stop

Day 3

A20 to Toulouse, D813 then D6113 to Carrcassonne


Day 7

From Bassan (just north of Béziers) A75 over the Millau viaduct to Cleront Ferrand then A71 to Vallenay for a first overnight stop



Day 8



A71 to Oleans then same route back to Rouen for the second overnight stop.

Day 9

Same route as day 1 but in reverse.

There are lots more pics on the Photobucket if your interested

Perhaps all with 3 bearing cranks should carry some sort of heavy band tourniquet. I have had no involvement with the engines, but the support for the centre bearing appears dubious even by 1923 standards. Based on experience with other makes, if a crankcase is not really rigid crank problems always threaten, although crank shape and finish has huge influence.
The oil pockets are quite different from the 2 brg but appear no more ideal. The shells sport only one drilling and no trench. I have often wondered if this hole functions as an inlet or exit, possibly to vent entrapped air. I ran my car with no drilling and no ill effects although seldom exceeded 4,000 rpm. Relieved areas near parting line, as most shells, not clearly evident in photos.

Location: Auckland, NZ

Good going until it all went bang Leon!

What car does your friend have? I like the look of it a lot.

We came up to the West of Toulouse and I know many of the place you came through from other A7 trips.

Sorry to hear of the CC demise - a good A7 Engine will carry you happily on another similar route - maybe not quite at 70mph but near enough. In 1999 I drove the Ulster from Bilbao to Glasgow in 6 days following a Riley 9 Special, a lot of fun. Our foreheads were black and engrained with road dirt, oil and bugs - despite almost constant attempts neither of us were able to secure a female passenger at any stage on the journey!

Good luck with the new engine build and don't be put off by the 3 bearing engine, my own experience of these is that if they are correctly set up they are one of the best A7 engines. I have many, many broken cranks in the "bin" only two are three bearing all the rest are 2.

Ruairidh

Awkward car is a Standard Avon special (1931 I think) running a Model A with a Riley over head valve conversion, if this wrong I expect Awkward will correct me.

The CC engine is now in my cellar half built up with a new block, I have removed the seven engine this morning and i am hoping to get it fully build up ready for the end of September for The 750MC meeting at snetterton (spectating only)

Good luck - that is a very neat engine and I really like the Standard Avon.