More info on the incredibly useful product.

Location: not north wales any more

Thanks Ruairidh and Hedd.

Steve V.

Location: Polegate, East Sussex

For info. Adam Brown who runs Craftmaster has a ruck of vintage tack. Including a 1930 AE Chummy just like mine.

Location: not north wales any more

Strayed somewhat from bores!

The 1920s idea of fitting b.es. so rods just drop was based on scraped bearings with high spots. If the crankpin unworn all around, it would now be considered too close for precision mated surfaces, given todays trend to hard use.

Applied to cars driven reasonably, belling must greatly reduce life. Close fitted parallel bearings looked fine on my RP held often at 50 mph and 30 mph in 3rd, 35 on occasions. I guess adequate piston side clearance is a factor.

Years ago significant filing of b.e.s and rescraping was regarded as a ritual part of any overhaul. The idea seems to have been to remove the hard abrasive layer which forms without a filter and thus extend crank life. (But in any case, with reasonable oil changes, the wear life of Seven cranks will likely extend beyond their fatigue life!)

I don’t know what standard practice of machinists is, but it would seem prudent to provide slight relief at the parting line, as built into shells.

Location: Auckland, NZ

At the risk of becoming a "cylinder bore" I thought I would share a recent experience.
I am in the process of rebuilding my RP engine. The engine was as it had finished our trip from BA to NYC in 2013. Although it produced a miasma of oil haze in the cabin, it went like stink, but the lubricant inhalation was probably not conducive to good health, so in anticipation of a trip beginning with the 750 Euro Tour to Salzburg and then down the Adriatic coast to Albania, by ferry to Italy and then Spain and home from Santander, it was time to rebuild.
I obtained another block and had it bored to +40, pistons and rings supplied by Jamie at the Seven Workshop. The actual bore size being as required on the ring packet. The advice from Jamie was to gap the rings 3 to 4 thou, however once bored and the rings inserted, the gaps were already 8 to 9 thou. I spoke to Jamie then went back to the machine shop, Guardias engine Services, where the bores were checked for finished size as well as the pistons and rings. The bores were actually a fraction undersize, the pistons exact, it turned out to be the rings that were too small/short.
Having discovered the source of the error I asked both for advice on what to do. Guardias are of the opinion that 9 thou is fine, he suggests 12 on a normal road engine. He has machined Austin 7 race engines with less clearance, but his experience is that it promotes bore and ring wear. Jamie would have replaced the rings if I wanted to try others, however I have settled for the existing items. There are two compression and two oil control rings per bore in split skirt pistons.
I want to emphasize that I have spoken to the supplier and engineer, both of whom were patient and thoughtful in giving their opinion and advice, I have no issue with either. Guardias say that in his experience of dozens of rebored engines each year, the rings are often supplied shorter than required to allow small gaps. Jamie reports that he is supplied by two different manufacturers and passes on their recommendations as to bore size and ring gaps.
I suppose you pays your money and takes your choice! Watch this space,in this instance 0.009".
(Answers on a postcard please to MR R.Dunford, Up North, Beyond the Artic Circle, Kiltshire)

Location: Foggy Cotswolds

There are many ways to skin a cat, my preference is to measure each piston individually and then bore to suit. The rings can then be adjusted, if required, to suit the bore.

The gap you have is not extreme by any means and will most likely serve you well.



p.s. I used to send my Grandmother a postcard from every holiday - another tradition bites the dust!

The ring gaps in my current Chummy engine are 0.010" - 0.012". I didn't build this engine, but a well respected Austin 7 man did. Runs well, with no problems.

Location: Wales

Ruairidh
Where did you find the 2 pages of info on that Timesaver compound.......I would like to do a printout but cant find that info on the company webpage.....also just trying a print of the forum page just wants to print the entire forum subject.

Dennis

It came with the powder when I bought it Dennis.

I will email you a copy of the photos to print out.

At one point it was very difficult to get. Newman tools in the states have all the guff on their website.

I have often been annoyed with replacement rings for other makes. To simplify work for mechanics and avoid comebacks rings were supplied gapped for smallest tolerance bore and gaps are generous on others, esp any honed. For worn engines many ordered rings .010 oversize.
Most textbooks and ring manufacturers recommend at least .003 per inch dia, altho the Seven and other oldies originally much less. Quite large gaps make surprising little difference to performance. The used refit limit for many cars was given as about .030. ACL ,major manufacturers in Oz, quote .005” per inch plus .001 as max for new rings pus another .010 for rehoning and wear. I supect large intial gaps are favoured for modern very slow wearing rings whereas most c.i.rings develop extra gap in first 10 minutes.

Location: Auckland, NZ

Hi Martin and others

My new Moore & Wright digital calipers and my new 3 prong glaze buster/hone have just arrived via Amazon, so have been doing a quick check. Initial results are cylinder bore in block 2.2285" and piston dia below rings at 90 deg to gudgeon pin 2.2285". No wonder my engine was tight. I hasten to add that the block is one that I obtained with the rest of the heap of spares and had already been bored. Not being used to A7 engines, I didn't think to check the bore size, but as it came with a new set of +30 thou pistons, I assumed that it would be OK. Anyway, now have to hone the bores to give the correct clearances.

When searching the internet for a 3 prong hone, I noticed that a couple of suppliers recommended using brake fluid as a lubricant whilst honing. Did you use anything as a lubricant when honing out your block?

Location: About 40 km SW of Limoges

From the sound of it, Tony, you did well to get the pistons in at all!

I used a few drops of light machine oil while honing, but I imagine that brake fluid would be just as good.

Location: Herefordshire, with an "E" not a "T".

I am very surprised, Tony, that you are able to obtain an accurate reading with a digital caliper.
I recently purchase a brand new bore gauge / comparator from Machine-dro.co.uk for around £40. Superb quality for the price, with a range from 2.0" upward.
The obvious usefulness is that it will accurately measure the whole length of a bore, ovality etc.
Chris

Location: Melton Mowbray

Hi Chris

I have a set of locking telescopic spring loaded bore measuring gauges. Basically a T shaped thing, the top of the tee being the spring loaded bit that fits inside the bore and the vertical of the tee being the handle containing a threaded rod that locks the bit that fits in the bore in position. Using this combined with the digital caliper allows the measurement of the bore at various points over the full length. I am sure that your bore gauge will be a bit more accurate but I think that what I have will suffice for now. I will insert a piston without rings in the bore tomorrow and see of I can get a feeler gauge between the piston and the bore and also carry out a more comprehensive survey of the diameter of the bores. Hope this makes sense!!!!!

Location: About 40 km SW of Limoges

I have the same gauge as you Tony. It's tricky to use but with care it gives good results indeed.

Location: Unsunny Brittany

This discussion seems to have gone full circle!

I'm with Tony and Renaud.

We've already established that with care, calipers can give an accurate result - mine isn't even digital!

Location: Herefordshire, with an "E" not a "T".

The Instruction for an Ammco surfacing hone is to use copious Ammco oil.

The instructions for a Ritch brand rigid hone state to use kero for finishing, followed by oil and 8 parts kero to polish.

Cutting is most rapid with oscillation as reqd for the cross hatch and with copious liquid.

Another source for a rigid hone reommends viscosity of 7.5 mm mm/sec, however that relates.

Ring manufacturers state that the bores should be scrubbed with soap and water until a white rag stays clean

I had a set of Jowett liners rebored by a practioner who claimed to have a suitable jig. The result was .003 out of round. He said he would refund if I could do better. So I spent a few days adjusting my super crudely made Indian lathe and did a set. I got my money back.

Finished with the Ammco hone with oil in kerosene.

If filing nails is too tedious a primitive version of the telescopic gauge is not hard to make. Working to one meaurement standard reduces errors which can quite easily stack up to .001. Hence the value of the feeler test.

Location: Auckland, NZ

Hi Martin & Renaud

Thanks for the endorsement of my measuring method. Hope I am not being a bore but I have just completed my survey and have found the following:-

All cylinder bores 2.2285" +- 0.0005 i.e. newly bored with minimal ovality or barrelling.

Piston - Top dia at piston ring location - 2.218"
Skirt dia parallel with gudgeon pin - 2.223"
Skirt dia 90 deg to gudgeon pin - 2.228"

i.e the skirt has 5 thou ovality

With the piston in the bore, there is absolutely no rock at 90 deg to the gudgeon pin but rock due to the 5 thou clearance in the plane of the gudgeon pin.

My question is, should there be between 4 and 5 thou clearance between the piston skirt and the bore at 90 deg to the gudgeon pin? i.e do I hone out the bores by 4 to 5 thou to give this clearance? Also, honing out the bores will increase the ring gap to at least 15 thou ( 5 thou x 3.142). Existing ring gaps between 10 and 13 thou (as supplied with the pistons)

All urgent responses will be much appreciated as I wont start honing until this is clarified to my satisfaction.

Location: About 40 km SW of Limoges

Tony, suggest you read all the posts in detail from the beginning.

Can readily detect .0002 difference in bore size with telescopic gauge or fitted nails, but accurately transferring and establishing the absolute length is tricky.
Feeler clearance is the ultimate test (assuming thin)

The side clearance is important; the piston expands more in that direction, and there is no give. And it helps accommodates crank flexing.

I do not know the recommended clearance for split skirt supplied when new but probably not more than .0015 with a feeler. Even a true .0005 should not be very tight to hand crank

.005 is racing clearance for a solid skirt piston.

The pistons must oscillate freely on the gudgeon after it is clamped.

Location: Auckland, NZ

HI Tony,
If you have split skirt Pistons those Sizes are spot on
if solid will need an xtra .0015

Hope That Helps Colin

Location: TINOPAI NZ

So another weekend of dodgy engine building comes to an end.

Just to make things clear, this is typical of the quality of scrap that I'm working with..............



This particular engine has donated its pistons, which have cleaned up surprisingly well, and is going to provide a matched pair of timing gears.

I ordered a tub of Timesaver Lapping Compound, which arrived the following morning. I'm very impressed; it only took a few minutes to ease the very stiff big end, so I gave the others, which were still a bit lumpy, a light application, with very satisfactory results.



As I still had some mixed Timesaver - which isn't cheap! - I decided to lap the flywheel (from a sixth engine) to the crankshaft with it and cleaned up the taper very nicely.



I struggled a bit finding a serviceable set of correct main bearings. Most of them appeared to have been buried for several decades and were seized solid. normal attempts at cleaning failed miserably. I eventually resorted to holding the inner race in the lathe (1913 Drummond "B"), while holding the outer race with a bit of wood and flushing with paraffin and oil. Most of the muck went up the workshop wall, but it worked and the bearings now run smoothly.

Location: Herefordshire, with an "E" not a "T".

Brilliant!

Location: Wales

Wonderful.
Takes me back 50 years to poverty stricken times.

Location: Bristol

Great stuff Martin. Your posts have inspired me to buy even more A7 junk at a recent auction to mix with my own pile that has been festering under the bench in the hope of creating something that can rattle out a good few hundred miles!

Unless the goo was just dried preservative grease, I am not sure that the resurrected races will be a success.
I dunno about mains but in most other auto applications any roughness is apparent. All rolling race surfaces need to be perfect for smooth running.
Almost any clearance wear in the roller bearings leads to rumble.
Parts from slightly worn roller races can sometimes be mixed to achieve a very close clearance, but can be hard to assemble. The a.c races can be shimmed but overdoing threatens the lip.

Both with Austins and others it always troubles me the way so many parts are ruined by rust and corrosion. Once any bearing surface is corroded it is rendered largely unfit for serious mileage. Parts reusable by the patient are rendered useless. And rebores, regrinds etc are unnecessarily triggered. Parts need to be preserved in grease; oil soon dries off.

Love Martins lathe with useful apron platform. Can it be accurately dated? Straight out of my fathers 1920s Model Engineer mags. Was it originally round belt drive? From a treadle? I wonder how many modern equivalents with diecast and nylon gears, fancy belts etc will be around in 90 years. The oil can also a museum piece.

I like what appear to be copper vice clamps. A device unknown to most commercial “mechanics”. It is what old h.w. cyls are for.
In most of the commercial garage workshops I have been able to explore, not even sheet steel clamps are to be seen anywhere. Nearly every
Seven dynamo shaft sports vice marks on the bearing journals.

Location: Auckland, NZ

Hi Bob. I'm not sure what the gunge in the bearings was, but after removing it the balls, rollers and races all appear to be unmarked, so fingers crossed!

Of my £100 budget for the rebuild, £65 or so is earmarked for a new set of piston rings - I only managed to recover 5 out of 16 - so buying new bearings isn't an option.

The lathe is a Drummond B - direct grandparent of the Myford 7 still very popular with model engineers. We've found the serial number and it's an early one, first half of 1913 according to http://www.lathes.co.uk/drummond/page5.html . Amazingly, after 104 years it still has a full set of change wheels and other accessories. It's worn, but adequately accurate. At some point it's been motorised courtesy of a pre-war Berkel meat-slicing machine!

The oil can came from elsewhere, but cried out to go with the lathe.

The copper vice jaw covers were the first thing that I had to make when I started the practical side of my professional engineering training. My mentor, Mr Cornelius, was very old school and wouldn't allow anything important anywhere near a vice without them.

Location: Herefordshire, with an "E" not a "T".

Bob,

You can buy reproduction oil cans here ........

http://www.hetheringtonlamp.co.uk/oils-cans-pourers/

Jeff.

Location: Almost but not quite, the far North East of England

Thanks Martin

Now you have mastered the hone, with that platform on the lathe you will be all set for mass production rebores.The problem with lathe work is that it can be more intriguing than Sevens...and safer.

Location: Auckland, NZ

Location: Herefordshire, with an "E" not a "T".

If anyone gets reeeeeally stuck finding an Ali welder then I can do it. I'm down near Cardiff airport.
I've welded new lugs onto lots of A7 nose pieces.

No charge, other than postage etc.

Rob

HFH200 @ hotmail. co. uk

Many thanks for the offer, Rob.

Location: Herefordshire, with an "E" not a "T".

Progress on the engine rebuild has been slow recently, but anyone who follows our Facebook page https://www.facebook.com/Martin-Prior-and-Sons-Motor-Works-1473477006309584/?ref=bookmarks will know that we've had our hands full with a couple of customers' RPs.

Anyway, I now have to confess to embarrassing ignorance. I'm planning to do some serious assembly of the engine over the weekend, but I can't for the life of me remember which way round the rear main bearing oil thrower should be fitted. I'm not even certain that there IS one on either the RP or the PD.

Should it be set up as in the first photo, or the second?

Anything else that I should know?!





Thanks!

Location: Herefordshire, with an "E" not a "T".

It should be like the second photograph, remember though that it goes inside that cover plate, not outside

Martin,
Take the ali plate off and then fit the washer between rear main bearing inner race and flywheel boss. The way round is as in bottom photo. Make sure that the oil thrower has a bit of a dish in it at its internal bore so that this dish is compressed between bearing inner race and flywheel boss as you tighten up the flywheel nut. Just get your ball pein hammer and tap out the dish shape on an old bearing of suitable bore size. The idea is that the thrower rotates with the crank and chucks the oil out and down the hole in crankcase and steel rear main bearing cartridge back into sump. So make sure the holes line up. I am doing the same job at the moment but getting frusrated because I can't find the front bearing retainer washer I removed 3 days ago.
Dave.

Location: Sheffield

Thanks, gents! All very clear, simple and logical.

A combination of the '33 Parts list and Mr Woodrow had conspired to confuse me!

Location: Herefordshire, with an "E" not a "T".

Hi Martin,

Sorry I'm a bit late to the party, I've been attempting to retire, whjich is proving a challenge as people don't want me to pack up, so I'm still doing the work, but with the staff I had!

I thought I'd share with you the fact (which sounds like an urban, or in my case rural myth) as the block really did come out from under a hedge in the village, that one of the best engines I ever had benefiited from rusted and badly pitted bores that after honing the pits seemed to hold a bit of oil, it never smoked and went like a train.

Good luck mate that engine will be a winner, even though it'll probably sound like a Maxwell House tin full of bolts!

Location: Near Bicester, Oxfordshire

Thanks for the encouragement, Ivor.

Having sorted out the rear main arrangements, this afternoon's frustration has been the discovery that the camshaft gear pulls tight against the face of the bronze bearing on what is probably the last half-turn of the nut.

This is far and away the best pair of gears that I have, so I guess that my only option is to fractionally ease the back face of the hub - unless anyone has a better idea.

Retirement? Ah, there's a nice thought. Some of my contemporaries have reached that point. My current estimate - honestly - is that I'll have to keep going for at least another 30 years. I'll only be 89 by then!

Location: Herefordshire, with an "E" not a "T".

Hi Martin,

Just a quick point, and hope it helps.

The rear oil thrower is one of the most important parts of the engine.

Its good to get it the correct way round.

But more important is what it's there for.

The thrower traps between the bearing and the flywheel.

If it traps to soon the flywheel will come look in use.

If it doesn't trap then the rear bearing will be free to spin on the rear main.

Which is why so many cranks are undersize on the rear main bearing.

Lap your flywheel in carefully. And get the interfearance correct.

Tony.

Location: Huncote on the pig

The original fit tolerance is very small. The blueprint which appeared in post Crankshaft a year ago shows 0 to + .00025. According info kindly provided by Tony Press, in 1964 tolerance for a standard bearing was -.0003 to +.0002, so some bearings may never have been tight (except due unmounted out of round). Currently 0 to - .0004.

Many cranks have had bearings fitted many times. In my car at least 7. As I have encountered with other makes, lazy “mechanics” may have eased the shaft slightly to simplify assembly/disassembly.

And with an easy fit it only takes a metal chip to briefly lodge sometime down the ages to trigger spinning.

The few throwers I have seen were plain. Needed stretching slightly to grip shaft. A thin neoprene washer/gasket could be inserted.

As a matter of interest, what is exact finished dia of Phoenix journals? Are they reground after nitriding? Or just polished?

And on a different tack, the groove in thrust surface of timing gear is the main oil supply to the timing gears.

Location: Auckland, NZ

Thanks, everyone, for the advice and suggestions.

The rear main situation is now sorted.

After much thought, I decided to turn about 0.004" off the back of the camshaft gear hub and that now has a couple of thou clearance from the bearing face.

Unfortunately, in playing around with this, I let the rollers from the camshaft centre bearing drop out. Fitting the little sods was bad enough with the camshaft out of the engine, but with it in, it's proving almost impossible. Any helpful suggestions?

Location: Herefordshire, with an "E" not a "T".

It's one of the great pleasures of Austin seven engine building.
Copious quantities of grease might stick them in. Or, you could find an old outer race, cut in in half and use that. Tied together with a bit of wire it will retain the rollers and push out of the way as the cam is fitted.

Martin. You'll have to take it out again.

Cam and grease in the freezer. Stick the rollers on with the cold grease then put an elastic band round them. Then refit

Location: not north wales any more

Quite a few people have asked me about progress on the rebuild of the scrap-bin engine.

Paying work has taken up most of my "spare time" recently, but we've made some progress. The main engine assembly has been completed; it turns over on the starter and has pretty reasonable compression.

The moment of truth is almost here. If I can arrange a quiet weekend, I shall sort out and fit a set of serviceable ancillaries and then.........?????

Location: Herefordshire, with an "E" not a "T".

Hi Martin

I see the new engine has solid engine mounts. Is this as the rest of your fleet?
Some claim notably more harsh although I found with thin rubber washers added, much the same.
A problem is that any mods raise the engine relative to the radiator.

Location: Auckland, NZ

Hi Bob.

I specifically wanted to build an early '33 engine and actually swapped a rubber-mounted crankcase for this one.

I have to admit that the rubber-mounted variety is more user-friendly. Years ago, I made the mistake of improvising this on my solid-mounted RP, only to find that the engine had almost completely detached itself from the chassis half-way up the motorway between Worcester and Birmingham!

Location: Herefordshire, with an "E" not a "T".

The Frankenstein engine lives!

We finally got everything together this afternoon and attempted a start.

We hoped to record a few pops and splutters. What actually happened was not quite what we expected!

Unfortunately, I have no idea how to upload a video to the Forum, but it can be seen on our Facebook page, Martin Prior and Son's Motor Works.

Location: Herefordshire, with an "E" not a "T".

This should work for the video Martin...


https://www.facebook.com/1473477006309584/videos/1873511362972811/

Great stuff ! See Video/Facebook for more extensive comment.

Location: Ferring, Worthing, West Sussex