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Author Topic: Seized engine strip  (Read 8599 times)
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« Reply #15 on: 10 September, 2008, 10:15:50 PM »

Speaking of matter, I think that my grey matter is also fast disappearing down a black hole near Geneva! 

It is about 12 months since I rebuilt an Aprilia engine and I should be able to remember - but I can't - however, I'm pretty sure that if you remove the starting handle dog, pulley, oil slinger and timing sprocket, then the drive gear will slide off the crank and disengage with the distributor shaft, leaving sufficient room to extract the crank.  I think.  Well, it has been a year and I'm getting to be too old for all this remembering stuff.  Have to write everything down these days.  I can remember when..............erm..............no I can't, come to think of it!

Morris. 
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« Reply #16 on: 10 September, 2008, 10:43:57 PM »

From looking at it I believe that would give clearance.  If desperate maybe taking the upper bearing shell out would do it?   Either way the pistons need to come out at some point and this is turning out to be the point to do it...

Thinking of CERN - at least I've DISproved the Big Bang theory for this engine.  Everything a bit siezed rather than "a failure".

David
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David Laver, Lewisham.
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« Reply #17 on: 11 September, 2008, 09:59:52 PM »

Morris,

More likely to be that your brain is clogged up with trying to solve Dilambda woes at the moment!  Roll Eyes

Robin.
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« Reply #18 on: 20 September, 2008, 07:35:53 AM »

I had new rings made for my pistons by a little old man in Maryport on the Cumbrian coast.  Cost £100 including some spare to allow for breakages.   Google Clupet Piston Rings - not only will you find the Clupet Piston Ring and Gauge Company but all sorts of fascinating side issues about the Clupet ring (big in steam engines).  Great stuff and very nice piston rings as well.  You may well, of course,be able to buy standard rings off the shelf.   My advice would be to hone the bores anyway and fit new rings after taking so much trouble to strip the engine...
David
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« Reply #19 on: 29 September, 2008, 05:27:55 PM »


No real time on it the last few weeks - but here's a couple of snaps from when I was.   The first bur went through the split pin like a knife through butter, but went blunt the first time it touched the bolt.  Turning the speed right down and the cut was almost as quick and the (next) bur didn't overheat and finished the job.  Probably only fifteen mins to do the lot.  That Proxon rotary handpiece is one of those tools that stays in the draw so long you almost forget its there and then every now and then really earns its keep.

I then used a little brass brush in it to decoke the bore tops.  The result is a jumper with little brass bristles that I still keep finding (still keep stabbing me) two or three washes on.  I think it will be a "proper" brass brush in a cordless drill to finish that job...  The little brush lasted half a bore.  Maybe its only supposed to be for sweeping dolls house chimneys.

No photo of the bore tops - but it was interesting to see the bore ridge had a top and a bottom.  The bottom edge is the usual wear from piston rings.  The top edge is because the bore was rough machined as far down as the wedge section - I can see little grooves from the tool - and this was larger than the fine machined/honed bore proper.  Yet to clean the piston tops to see if its an oversize.

David


* SplitPins.jpg (58.07 KB, 600x450 - viewed 222 times.)

* BigEnd.jpg (71.87 KB, 600x800 - viewed 236 times.)
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« Reply #20 on: 02 October, 2008, 02:42:15 PM »

It sounds as if your bores are not up to much and I would say from the appearance of the big end in your picture that that is knacked as well.Looks like a job for Serdi!!   See my posts.  It ain't cheap but is worth it in the end because my engine is now running beautifully and, with modern oils, should last at least 100,000 miles.
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David Wheeler.  Lambdas, Aprilia, Fulvia Sport.(formerly Appia and Thema as well).
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« Reply #21 on: 02 October, 2008, 03:33:27 PM »


There's an intellectual appeal to "strip, clean, reassemble" and bringing a seized engine back from the dead - aside from not spending the money or waiting on others.  At the moment its hobby time, a distraction, fun.  Throwing money at experts (at this point in the project as a whole) is about as sensible as paying someone else to drink down the pub in my place.   All I want from THIS engine is "a runner".  I can put up with low compression, low oil pressure, some smoke, down on power. 

If I've got a running engine sitting on a stand, pumping water through its rad, charging its battery, ticking over sweetly its a good step towards a living breathing car just itching to go out on the roads or sprint up a hill - its great motivation to push on with the rest of it.  WHEN the rest of the car is finished, IF at that point the biggest problem I have is that the engine is bit knackered THEN it might come to bits again and get done "properly".

At that point it will be an "urgent" job and it won't sit in the back of everyone's works getting forgotten or having a few hours thrown its way as a time filler.  If the work is expensive, if its the difference between a "run round the block" car and something that could really be used and I've got planned use for it then selling another car to fund the engine would seem a reasonable thing to do. 

My "other" Aprilia engine, at the time destined for an Austin 7 chassis, started at Baldynes who made no progress to speak of and then to BWE who then sent some to Serdi and some to Gosnay's and some to Jim Stokes and got some pistons made by some place in the states and - at the end of the day - at the end of five years plus - I still wasn't convinced many of the mods were actually all that sensible and I'm not at all sure that the bits that didn't go missing along the way will actually go togeather at all.

Perhaps this seized, knackered, engine will just be the spare.  Maybe the other one will get built up and prove to be a corker.  Maybe this one will come apart and get done "properly".

The objective is to breath life back into it rather than restore to the peak of fitness.  Meanwhile I'm having fun, and keeping my powder dry.

David
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« Reply #22 on: 02 October, 2008, 03:52:29 PM »


BUT DO KEEP THE ADVICE COMING!!

Its not just hands on experiance and tips for where I'm at - I'm also lapping up the help ready for when I either "make a proper job" of this engine or push on again with the other.

...and when I come to measure up the pins and bores it well may prove too far gone...the dream of a "strip, clean, reassemble" may die...but in the meantime I chug on in hope...

I'm also reassured by tails (from the 50s and 60s) of how long Aprilias would keep going in the most appalling mechanical condition. 

David
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« Reply #23 on: 02 October, 2008, 10:50:31 PM »

David,

I am pleased to return to this theme and I do agree with your approach of doing the minimum to get it up and running.

Purists and rich men should look away at this point, but I reckon you might well get away without a crankshaft reground and new white-metalling. When you have it fully dismantled, and if the white metal doesn’t look granulated or run-out, and if the crank ovality is not that bad, then I think you could do a good, cheap and pleasurable job simply by ‘stoning down’ the bearing caps and scraping the white metal to fit.

This was commonly done in ancient times and it worked. You need to measure the ovality of the crank and I seem to recall that if it’s no more than something between 5 and 10 thou then it’s OK. Then use silicon carbide paper laid on a bit of plate glass with paraffin on the surface of the paper and thin-down the caps with a ‘figure of 8 motion’ to get a uniform cut to the desired depth. Then clean it and bolt it up with ‘engineer’s blue’ on the surface of the white metal to reveal the high spots and then use a hand scraping tool to cut the white-metal back. Repeat a thousand times until you have a ‘good fit’ for each of the mains and ends.

Actually, I only ever did this once on an Aprilia engine, but it was about the most pleasurable of all jobs I have ever done on a car and it lives in my memory. And it worked – with lots of oil pressure and no rattles. Also, as a job, it combines the pleasures of woodwork-like ‘scraping skills’ with the precision of metal work. I am sure you would enjoy it!

I don’t doubt David Wheeler’s quality of experience with Serdi and Vibration Free. But I have to tell you that I hear that the latter has amongst its specialist tools a powerful invoicing machine that is heavily geared so that once it is running it’s difficult to stop – this could be painful.

Keep up the good work and having fun!

Colin
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« Reply #24 on: 03 October, 2008, 09:52:16 AM »

My Austin 7 special started with a "get you going" engine - which got me going. 

I then built up a engine with all the (then) tricks - a reliant crank and shell bearings and modern pistons and pressure feed and a spacer plate to raise the block and a modified flywheel and bits ground off here there and everywhere to get it all to fit and it was great while it lasted - but it didn't last all that long...and nobody seemed to get theirs to last all that long either... 

Running out of time for an event (working on a duel oil pump setup I thing it was) I took "a bucket of bits" - I stoned down some caps and hand scraped the white metal and thumped it about until everything was in and free.  I did use new rod bolts and new nylock nuts everywhere but it was second hand pistons with their original rings and a missmatched set of rods with no attempt to balance it and worn ball and roller bearings for the crank and a standard oil pump etc etc.   That "stop gap" engine is still in the car.   Aside from some new nuts and bolts it does have a modern oil filter.

Maybe the engine in the Austin 7 will get what's now the conventional replica crank and rods and professional remetal.  I'd love to start from scratch again and built a reliant crank based engine as there are advantages for all the labour charge would be so great that it can only really be an amateur effort. Maybe maybe maybe.  Meanwhile there's an engine in the car that goes plenty well enough.

So that's something of the background.  Aside from a lot of money over a long period of time into an Aprilia engine that never came togeather I've also been somewhat burned by over complicating an Austin 7 engine build.  I've also had great service from something rebuilt from worn out and mismatched bits. 

So fingers crossed !!   Both that it does work out well, and that I get the rest of the car togeather before it seizes up again.  At least as a stand alone "power pack" it could be run on high days and holy days.

David
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« Reply #25 on: 06 October, 2008, 04:09:31 PM »

  In defence of Vibration Free, they charged me exactly half what they should have done because the engine took a very long time to balance with the new rods.  On the other hand, if it had not been rebalanced, it would not have run at all.  I think the bill was in the order of £350+ VAT.
  I too put a "runner" in the car that I had got from Julian Bolton and which had been in a Farina tourer but it failed its second MOT because of excessive smoke!  It rattled horribly too and I felt quite unable to go anywhere far for fear of a big end giving out. The oil pressure looked fine but merely reflected the choked oil ways.  I don't know how much remetalling costs nowadays, it might not be much less than the conversion to shell bearings but then there is the cost of rods etc. which is a lot.  Please do not grind down the caps!! It may be OK for an Austin seven, not the most stressed engine in the world but I doubt if it would be good enough for an Aprilia and ruins the rods for ever more unless you are incredibly skilled.
   I ran the Lambdas on white metal for many years (the VIIth is still on them) so I know they are good for 30,000 miles or more so that would be a route to go if the big ends are not badly worn.  If they need to be reground make sure that does not mean excessive white metal thickness on the resulting bearings as if it is too thick they will fail.  I was going by the photo which looks as if the bearing surfaces are quite badly scored.  If they are not then you should be fine.  Plastigauge is useless but newspaper is usually 2 thou thick and will help you to determine the bearing clearances.
I found Serdi to do a very good job but you just have to ring them up every couple of weeks or so to keep them going otherwise your job gets displaced.  They do have the proper jigs for reboring Lancia V4 engines, not to be done by the tyro in your local machine shop as the geometry is not simple.
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« Reply #26 on: 06 October, 2008, 06:51:26 PM »

Quote
If they need to be reground make sure that does not mean excessive white metal thickness on the resulting bearings as if it is too thick they will fail.

theoretically anything under .014 inch is desirable and in general the thinner the better.In fact this dimension (0.014) is the point at which durability starts to improve. (all other conditions being equal). If reduced to 0.008 the durability already doubles and more than doubles again by 0.004. Of course if you have to grind too much off in the first place you will have thicker white metal bearings but reduced durability resulting in more frequent rebuilds which starts to change the cost equation of fitting shell bearings.!

white metal is soft and the thicker it is the greater the relative compression and working it experiences during the engine cycles.Simply put it experiences more fatigue the thicker it is and is prone to earlier failure.
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« Reply #27 on: 06 October, 2008, 07:37:50 PM »


The newspaper-shim tip was a good one.

New metal for rods isn't expensive at all - its when the mains need doing and the job needs setting up for a line bore that the price goes skywards.   These rods have shells with the white metal over.  My memory of the other one was white metal directly onto the alloy.  It gives a third option of new undersize shells with a new thin deposit of white metal.  Option four is a set of new alloy rods - when the other engine was being "progressed" (hohum) they were not available but now there's a fair choice of suppliers.

By the magic of the interweb here's a price list:-

http://www.johnsonsengineers.com/jel_prices.php

Are phoenix rods 150 each?  Add in the rebalance so perhaps modern shells is an extra 7-800 but of course that also buys the peace of mind of the new steel rods and beautiful smoothness.  Would make sense on an engine with the valve train worked to increase the rev limit.  My memory of the BWE recipe was thinner stems on the valves, alloy spring retainers (but looking at the steel ones its hard to imagine much gain there), and a slight increase in spring weights.

David
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« Reply #28 on: 06 October, 2008, 07:41:26 PM »


When I get the bearings clean I'll try and take some accurate photos.

Anyone know what a tollerable bore clearance might be?

David
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« Reply #29 on: 06 October, 2008, 08:01:07 PM »

http://www.johnsonsengineers.com/jel_gallery.php

There's a picture of a "Lancia V8 Dilambda with new mains and big ends
ready for crankshaft fitting".

Alloy rods wouldn't worry - they picture a "Re-metalled and machined Triumph Speed Twin connecting rod. Aluminium rod and steel cap".

Its also interesting to see VERY thick bearings.  I expect the alloys vary enormously... 

http://en.wikipedia.org/wiki/White_metal

This link has an interesting list of types of rod. 

http://homepages.tesco.net/harle71/harle71/bearings.htm

I understand many drag racers have an alloy rod run directly on the crank with no additional bearing material but I didn't realise Lagonda did the same prewar.  Perhaps the crank was particularly hard or maybe plated.

John Kirkby is the one name that keeps coming up for "regular" cars, and Formhalls for the Grand Prix sort of stuff.

http://www.oldclassiccar.co.uk/restoration/white_metalling.htm
http://www.classiccarwebsite.com/home/c4973_white_metal_bearing

David
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