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Author Topic: Aprilia engine rebuild.  (Read 8441 times)
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ben
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« on: 28 May, 2010, 08:28:12 AM »

      This thread follows my piston enquiry in the Fulvia section.
      As some of you know I have been running my Aprilia (on a shoe-string budget) for many (46!) years now. During this time I have changed the engine twice but each change has been compromised by my financial circumstances and prevailing priorities. The current engine came from a car that I broke up for spares about 20 years ago and is now suffering from a loose big-end bearing that rattles alarmlingly on start-up until the normal rather modest oil pressure is achieved. I have two spare but worn-out engines and recently acquired a third (along with another engineless car which I bought for longer term restoration).This third "spare" was seized solid.
      So the answer to the "What stage is your project at?" question is not straightforeward! My current priority is to rebuild the best of my three engines to swap into my original car. I can then rebuild an engine for the "new" car at my leisure.
      My initial assessment was that the seized engine was the best option.The usual corrosion in the waterways in the block did not look too bad, the valve gear was/is good, but despite prolonged soaking with Plus-Gas the pistons remained seized.I removed the sump,crank,etc to enable me to drive out one piston at a time but to no avail.
      Finally I resorted to cooking the whole block in my domestic electric oven.After soaking at 280+degrees C for an hour or so (during which time as you may well imagine the room and to some extent the whole house filled with not entirely sweet smelling fumes) I swiftly transferred the unit to the coffee table and set about it with a specially made drift and a large hammer.Somewhat to my surprise the liners moved before the pistons did! After two such heating cycles I now have two liners out completely with pistons still stuck in them and two liners part way out with the pistons removed.
      What this exercise has shown me is that my initial asessment or the corrosion in the waterways was much too optimistic. With the liners removed it is evident that the aluminum has corroded right through in several places and this block is not re-useable even if new liners were available.
      In the light of the above I am now re-examining my options. My other engines are both already bored to +60 but one is originally 72mm S1 and the other the slightly bigger S2. Does anybody know if the liner OD is correspondingly bigger?
      Incidentially David I dont think re-sleeving these engines without removing the existing sleeves is an option as certainly either if not both the remaining old and the new sleeve would be too thin.
      If anybody is interested I could bring some of the bits along to the sliding pillar rally.
      For further updates watch this space.
                                                           Ben
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fay66
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« Reply #1 on: 28 May, 2010, 02:49:37 PM »

Ed Levin on the Lancisti.net American Forum, has suggested a real frozen component shifter is nail varnish remover, (Acetone), not the environmentally friendly version,  mixed with 50% Automatic Transmission Fluid (ATF)  is much better than many well known products.

Brian
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davidwheeler
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« Reply #2 on: 31 May, 2010, 08:25:47 AM »

I have just checked the books, first series is 72mm and second 74.61mm.  I have bored a first series engine out to 74.6mm to take some second series Nardi pistons with complete success.  New rings were made by Clupet Piston Rings in Maryport, just down the road.  I have some 60thou oversize first series pistons, new, which I will check for you.  Maybe my old first series block will be able to take them.
Changing pistons, converting to shell bearings etc. will upset the balance of the engine and the only solution to that one is Vibration Free.
David
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David Wheeler.  Lambdas, Aprilia, Fulvia Sport.(formerly Appia and Thema as well).
ben
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« Reply #3 on: 19 January, 2015, 08:41:17 PM »

   Cannot believe it is nearly 5 years since I started this thread!!
   I was concerned about the big-end wear in the engine in the Aprilia and decided to rebuild a spare engine that could then be swapped over.
   Interestingly in view of the discussion on here a while back about the vulnerability to fatigue failure of 75 year old alloy con rods the only bits of the seized engine (which I struggled so hard to dismantle back in 2010) were the rods.
   I am afraid to say that I have not been very conscientious in submitting progress reports but I have now built up an engine using an S2 block and a set of Fulvia pistons from Italian ebay.The block bores averaged 75,25mm suggesting it had had a +0,5 or 0.6mm rebore and I was able to get away with honing to suit the 75,6mm Fulvia pistons.I had to have the rod small ends machined and bushed to suit the Fulvia gudgeon pins (Fulvia 22,02mm cf Aprilia 22,20).The rod big ends and S2 crank are machined to suit Alfa shells (VP 203 std,45mm dia ie std S2 crank -0,5 mm). The wedge top pistons give me a compression ratio of about just over 7:1. As they weigh about the same as the original ones I have not gone to the expense of balancing.
   However despite the rattling on start up my original engine is still going reasonably well so the new engine has been sitting on the bench until recently when I decided to build a test stand and run it and verify it is ok. Initially it started and ran fairly smoothly but would not idle.This was traced to a carb fault (which I can elaborate on if anyone is interested) but having cured it I discovered a nasty rattling noise coming from the valve gear at a narrow rev range just above idle. I then fitted my cut-away valve cover and was able to see the timing chain leaping around when the noise occured. 
   It seemed reasonable to deduce that I had not got enough pressure on the spring-loaded idler.Which brings me to the problem that triggered me to write this post!
   So does anyone know how much "wind-up" one should use when installing the tensioner spring anchor?


* Aprilia timing chain 002.JPG (1762.45 KB, 3072x2304 - viewed 128 times.)

* Aprilia timing chain 001.JPG (1752.75 KB, 2304x3072 - viewed 136 times.)
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ben
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« Reply #4 on: 20 January, 2015, 10:42:04 AM »

For interest here is the test bed.

                                                Ben


* !cid_40726F0E-F147-45CD-9AF6-831368FB3661.jpg (112.51 KB, 640x480 - viewed 383 times.)
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Richard Fridd
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« Reply #5 on: 20 January, 2015, 10:48:08 AM »

Which one is the chief tester?
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Richard Nevison Fridd
ben
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« Reply #6 on: 20 January, 2015, 10:58:23 AM »

Whoops---not quite what I intended!

Will try again.


* !cid_FFBC761A-5597-4624-BF31-1DF6735F7D9D.jpg (566.81 KB, 1224x1632 - viewed 124 times.)
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the.cern
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« Reply #7 on: 20 January, 2015, 11:51:57 AM »

Excellent Ben. As a matter of interest, where does the exhaust go? It looks like a stubby!!!!!!

                             Andy
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DavidLaver
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« Reply #8 on: 20 January, 2015, 02:00:15 PM »


We've had all these before but now seemed the right time for a rerun:

https://www.youtube.com/watch?v=KIUAM28vsI0

https://www.youtube.com/watch?v=1e1xW82nrIQ

https://www.youtube.com/watch?v=8l69fyX3El0

https://www.youtube.com/watch?v=rp5ArPRb8o4

https://www.youtube.com/watch?v=fNTlqSPt2c4
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David Laver, Lewisham.
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« Reply #9 on: 20 January, 2015, 02:07:00 PM »

More exotic - but they made the mistake of leaving the exhaust system in place...

https://www.youtube.com/watch?v=SFT1x5h1hGM

...and just because its the same place:

https://www.youtube.com/watch?v=UmAIE8QRos8
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David Laver, Lewisham.
ben
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« Reply #10 on: 20 January, 2015, 04:18:27 PM »

 My set up is muffled. The neighbours have enough to put up with already.

 Also I think an open system like the Polish(?) guys might have set my wooden stand on fire.

 I had not seen the American rebuild before. Very impressive standard---wonder if is intended to race or just sit in a museum.

 And as for the engine in the Pagani---what an amazing set-up. Not many like that around!  Was it by Nardi do we know?
 


* Aprilia test bed 002.JPG (1741.59 KB, 3072x2304 - viewed 130 times.)
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lancialulu
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« Reply #11 on: 20 January, 2015, 05:35:15 PM »

The American run was very impressive with exaust flame outs. Wonder if it had more radical cams??

Love Ben's DIY setup.....
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« Reply #12 on: 20 January, 2015, 07:38:18 PM »

Love it !

How much vibration is there ? I had this feeling that test-bench set ups are vicious and uncouth but I would love to try one and am now inspired !

Re "wind-up" ,  I have an engine in bits and will look.

Re carb problem - more details please
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DavidLaver
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« Reply #13 on: 20 January, 2015, 08:56:56 PM »


Test beds make so much sense...and is there an easier setup than the Aprilia's power pack? 

Maybe something air cooled would be.

David
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David Laver, Lewisham.
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« Reply #14 on: 20 January, 2015, 09:33:43 PM »

Ben, that really is impressive. I hope that it helps identify any problems.

I think I have two engine rebuilds now, the B20 and the Gussie. The former because it is seized. The latter as it is has to come out to allow a full inspection of the front end of the sills and because it has been standing for, let's guess at 15  years, and it just seems sensible to at least check the bores ... maybe now would be a good time to attempt to make a stand that will take both engines, even though they are so different!

                                        Andy
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