Lancia Motor Club

Model Technical and Interest => Aprilia, Ardennes and Ardea => Topic started by: ben on 28 May, 2010, 08:28:12 AM



Title: Aprilia engine rebuild.
Post by: ben 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


Title: Re: Aprilia engine rebuild.
Post by: fay66 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
8227 8)


Title: Re: Aprilia engine rebuild.
Post by: davidwheeler 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


Title: Re: Aprilia engine rebuild.
Post by: ben 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?


Title: Re: Aprilia engine rebuild.
Post by: ben on 20 January, 2015, 10:42:04 AM
For interest here is the test bed.

                                                Ben


Title: Re: Aprilia engine rebuild.
Post by: Richard Fridd on 20 January, 2015, 10:48:08 AM
Which one is the chief tester?


Title: Re: Aprilia engine rebuild.
Post by: ben on 20 January, 2015, 10:58:23 AM
Whoops---not quite what I intended!

Will try again.


Title: Re: Aprilia engine rebuild.
Post by: the.cern 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


Title: Re: Aprilia engine rebuild.
Post by: DavidLaver 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


Title: Re: Aprilia engine rebuild.
Post by: DavidLaver 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


Title: Re: Aprilia engine rebuild.
Post by: ben 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?
 


Title: Re: Aprilia engine rebuild.
Post by: lancialulu 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.....


Title: Re: Aprilia engine rebuild.
Post by: simonandjuliet 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


Title: Re: Aprilia engine rebuild.
Post by: DavidLaver 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


Title: Re: Aprilia engine rebuild.
Post by: the.cern 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


Title: Re: Aprilia engine rebuild.
Post by: stanley sweet on 21 January, 2015, 10:21:15 AM
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

Is there any reason why rubber mounts couldn't be fitted to soften it?


Title: Re: Aprilia engine rebuild.
Post by: lancialulu on 21 January, 2015, 12:24:12 PM
Is there any reason why rubber mounts couldn't be fitted to soften it?
Aprilia engine is so sweet it does not need it. A gamma on the other hand on start up would rip the wooden structure to matchwood!! (Even with rubber mountings!).


Title: Re: Aprilia engine rebuild.
Post by: ben on 22 January, 2015, 10:32:18 PM
  The Aprilia engine is indeed smooth but interestingly it is on rubber mounts all-be-it quite small and therefore stiff ones. They are visible in the test-bed picture and are in series with the triple leaf springs.
  I have now reset the tensioner spring using one complete turn of wind-up and it seems to have cured the chain whip.

  The carb proplem referred to previously was due to an air leak between the float-chamber and the carb body.This is the standard Zenith which has a poor design feature in this respect.The float chamber is held in place by two vertical screws holding the chamber up against the lid which is integral with the body but it also has to seat tightly against the vertical face.On my carb the two faces were not exactly ar right-angles.The screws ensure a good seal between the bowl and the lid but a leakage gap was unavoidable where the jet feeds into the venturi. Hence the engine would run but was too lean to idle.
  The rather poor photo shows the metal strap I fabricated to hold the bowl side against the main body. Instant gasket was used to seal the lid and the screws were tightened with minimal torque.
   The long term solution could be;
                        make a thin wedge shaped gasket to get the faces at right-angle. (V Tricky)
                        machine the carb to correct the angle  (Also V Tricky)
                        bend the carb lid down to correct the angle---anyone tried to bend mazac(?)
                        scrap the carb and find another one.  Any offers?

   There was another problem that the test bed revealed which I had forgotten about when I posted the original story.
   After fitting the radiator and water pump both of which required lots of fettling to get them watertight I filled up with water and left it overnight. Trying the first proper start-up the next day I was surprised at how much top-up was needed but the engine did start and ran although would not idle as described before. What was less satisfactory was the amount of water that emerged from the exhaust!!!
    The first suspect was the head-gasket and the first step to removing the head was to remove the manifolds.
    When I removed the exhaust manifold i noticed water dripping from the No 2 exhaust port.I was still thinking the head gasket was leaking but when I got the head off there was no obvious sign of a problem and also there was no water in any of the cylinders.
    I will leave you to ponder on this mystery until I have taken some more pictures to post.
    Meanwhile back to the wounded carburettor!   


Title: Re: Aprilia engine rebuild.
Post by: nistri on 23 January, 2015, 07:07:34 AM
Thank you for  the very interesting info. Just for the record, is it OK to re-use copper head gaskets?
Regards, Andrea


Title: Re: Aprilia engine rebuild.
Post by: simonandjuliet on 23 January, 2015, 07:37:32 AM
Fascinating !

Couple of questions/points. It looks like you are running the engine with the cut-away rocker cover fitted, how much oil gets thrown around ?

Re carb, I am not sure I would try bending mazak, it is such an unfriendly material. I have found that plastic metal sticks very well to it , maybe you could build it up and machine the plastic metal ?

Re water leak, have you got a crack in the head around one of the internal exhaust castings ?

When refitting your headgaskets, do you soak them before re-using? I know there are mixed views about this, but I have often re-used the copper/asbestos gaskets without problems, but have always left them in a bowl of water for a day beforehand. What is the state of the central stud post ? They can be very messy !

Good luck with the carb and if you want a new headgasket I can help out ...


Title: Re: Aprilia engine rebuild.
Post by: the.cern on 23 January, 2015, 09:24:34 AM
Picking up on a couple of points ...

I agree with you Simon about bending mazak, I have never been successful no matter how careful I think I have been .... and I have found there is absolutely no warning for the point of failure!!!

Simon, I have not heard that tip for re-using copper/asbestos gaskets, but I will certainly use it.

Andrea, I have no experience of this, but understand that copper head gaskets may be re-used. It is advisable to anneal them first.

Ben, I love the 'repair' of the carburettor. That is a real engineering solution to overcome an inherent design fault.

                                 Andy



Title: Re: Aprilia engine rebuild.
Post by: ben on 23 January, 2015, 08:38:30 PM
 Back in 2008 there were a lengthy series of posts, started by David Laver, about the two types of inlet manifold found on Aprilias and the provision for pre-heating either with exhaust or water.It was generally concluded that the use of exhaust gas was perhaps only featured as an experiment or only on very early cars before the water-jacketed manifolds we are familiar with were introduced. However all the cylinder heads that I have looked at have the entry "port" into the "cast in" transfer passage filled with some sort of compound to blank it off.
For the engine I have on test I had cleaned out this material to open up the passageway.In practice I did not expect it to make any difference because the port is still blanked off by the head gasket.
The first two photo's show this.   


Title: Re: Aprilia engine rebuild.
Post by: ben on 23 January, 2015, 08:42:26 PM
Sorry,pressed "posr" by mistake!


Title: Re: Aprilia engine rebuild.
Post by: ben on 23 January, 2015, 09:28:00 PM
On the face of it if one wanted to feed water through this channel to the manifold one would need to make a hole in the gasket adjacent to the central stud to let the water in.
On my engine although I had not made such a hole the water did get into the transfer passage because the gasket is unsupported on the other side at that position which allows it to bulge down into the block. (See next picture)

One would expect this water to merely feed into the cooling chamber in the manifold.

However this is where we finally get to the interesting bit. After 50 years of ignorance I have discovered*****

THERE IS A FEED HOLE FROM NO.2 EXHAUST PORT INTO THE TRANSFER PASSAGE.

I have marked it with a blob of white Tippex in the last photo.

And of course that is why the water in my engine ran out of the No 2 exhaust port and filled up the silencer!

So it would seem that inlet manifold heating using exhaust gas is and always has been a feature or all(?) Aprilia engines! Both cylinder heads that I have been able to check have this feature and I believe one is early and one is late.
Just how much good it does is open to speculation o course but it seems significant that the feature was carried over when the manifold design changed from square to round.In fact as the inlet port sizes are more or less the same on both manifolds the main reason to introduce the round type was presumably to make the heating more efficient.
As far as I can judge this heating is purely to avoid icing up although the heat has to migrate up into the carburettor to achieve this.



Title: Re: Aprilia engine rebuild.
Post by: ben on 23 January, 2015, 09:49:51 PM
And to respond to the point about gasket re-use I have certainly re-used the same one up to 3 or 4 times on a standard engine---usually with a smear of red Hermatite.  Nowadays it would be Hylomar I guess.
With my raised compression ratio I might use the annealing and soaking tricks .
And I have a new spare just in case thank you Simon.

Regarding the query about oil splashing with my cut-away rocker cover, at idle there is no problem, but a certain amount of mist is spread around when the revs are increased.

After re-setting the spring tension for the timing chain I ran the engine without the front cover back on but that led to quite a severe loss of oil.Of course there was still no water in it at that stage so it was only a brief run---but long enough to see that the timing chain whip had gone away.


Title: Re: Aprilia engine rebuild.
Post by: simonandjuliet on 26 January, 2015, 05:14:44 PM
I will check my spare heads tomorrow and see if they are the same..... but all very interesting


Title: Re: Aprilia engine rebuild.
Post by: ben on 26 January, 2015, 11:58:58 PM
Hi Simon
            Note that when you check your heads the cylinder and exhaust port that I refer to as No 2 is the second from the front (which is No 1 cylinder in Lancia's "round the block" firing cylinder order!).


Title: Re: Aprilia engine rebuild.
Post by: Dilambdaman on 28 January, 2015, 04:10:57 PM
Certainly seems to have been something favoured by Lancia as it is found on the Dilambda.

An alloy cast box is fitted between the carb and the block with two internal passages to take fuel to the inlet valves. The space surrounding these passages is connected by a small bore pipe to the exhaust manifold allowing the exhaust gasses to warm the fuel mixture. The box has a water drain off tap and on the S2 a take off for the brake servo.

In use the alloy corroded badly and somewhere, although I can't locate it to photograph, I have one that came in completely wrecked state with Modestine. All of the Dilambdas that I have seen to date have had the pipe removed and the holes in manifold and box blocked. General consensus seems to be that modern day fuels don't need warming to perform well.

Robin


Title: Re: Aprilia engine rebuild.
Post by: simonandjuliet on 29 January, 2015, 04:12:24 PM
DiLambdas are complicated beasts !


Title: Re: Aprilia engine rebuild.
Post by: davidwheeler on 16 February, 2015, 11:52:35 AM
On the face of it if one wanted to feed water through this channel to the manifold one would need to make a hole in the gasket adjacent to the central stud to let the water in.
On my engine although I had not made such a hole the water did get into the transfer passage because the gasket is unsupported on the other side at that position which allows it to bulge down into the block. (See next picture)

One would expect this water to merely feed into the cooling chamber in the manifold.

However this is where we finally get to the interesting bit. After 50 years of ignorance I have discovered*****

THERE IS A FEED HOLE FROM NO.2 EXHAUST PORT INTO THE TRANSFER PASSAGE.

I have marked it with a blob of white Tippex in the last photo.

And of course that is why the water in my engine ran out of the No 2 exhaust port and filled up the silencer!

So it would seem that inlet manifold heating using exhaust gas is and always has been a feature or all(?) Aprilia engines! Both cylinder heads that I have been able to check have this feature and I believe one is early and one is late.
Just how much good it does is open to speculation o course but it seems significant that the feature was carried over when the manifold design changed from square to round.In fact as the inlet port sizes are more or less the same on both manifolds the main reason to introduce the round type was presumably to make the heating more efficient.
As far as I can judge this heating is purely to avoid icing up although the heat has to migrate up into the carburettor to achieve this.


Well, that solves a 40 year old conundrum.     I bought a series 2 "Nardi" engine from Julian Bolton who had taken it out of a convertible and put it into his 'Nash.    When I put it together, water poured out of the exhaust so I replaced the head with a new one I had bought from Cavallitto in 1971 on my first Lambda trip.    This does not leak, I know not why and I am not going to look as the car is going well.   I have just looked at the "Nardi" head and it has the passage from No 2 port to the transfer channel.   You now have the block from that motor.   I now wonder if there is any difference between a Nardi head and a standard one???

The Lambda is much simpler - just site the carburettor between the branches of the exhaust manifold and hope it does not leak too much!


Title: Re: Aprilia engine rebuild.
Post by: ben on 06 June, 2018, 04:42:11 PM
When I started posting on this topic back in 2010 (yes, eight years ago!!!, ) my final comment was "  For future updates watch this space "

I then reported on bench testing the replacment engine in 2015.

I can now tell all you patient space watchers that as of yesterday the engine swap has finally been accomplished.

It speaks volumes for the ruggedness of construction of Aprilia Vee Fours that the previous engine has soldiered on with its rattling bearing for several thousand miles in this time including three Sliding Pillar rallies.
However it had got to the stage earlier this year where even under cold start conditions  the oil pressure only just reached the"Normale" zone on the gauge. At working temperature the needle was only just off the stop.

Some interesting observations concerning the engine change include;
                    I had forgotten that I had been using an S2 clutch whereas I had built up the spare unit with an S1 clutch.On the face of it it seemed sensible to retain the S2 item but this would have entailed changing the flywheels over and I was reluctant to do this having test run with the S1 one. Time will tell if this was wise. The S2 clutch has a 7.5" plate and a big central spring where-as the S1 plate is only 7.0" diameter and has the six hairpin springs around the rim. Aside from balance questions the flywheels are a tight fit on their mounting spigots and the fixing bolts have very slim nuts which are locked by spot peening and prone the stripping their threads.
                   The engine has to be hoisted in a very steep "gearbox down" attitude to get it into position--see photo---and if it already has oil in it it runs out through the rear maim bearing making a mess on the floor!
                   If the inlet manifold is taken/left off prior to installing the engine (to provide easier access for installing the starter-motor and in particular the actuating cable which runs around an otherwise highly inaccessible pulley wheel) it cannot be refitted over the mounting studs because the steering column is in the way.So either three of the four studs have to be removed and refitted with the m/f in position or the engine has to be raised up again far enough to give the necessary clearance. Which is jolly annoying if you have already bolted it in place!!
                  Also as a general point it is interesting to note that mechanics of the period (1937) probably did not use (or have?) ring spanners or sockets because many of the nuts can only be accessed with an open ended spanner. 14 mm AF is a very common size on the Aprilia which purists like to retain whereas switching to 13mm AF gives a bit more room and is a much more readily available replacement option nowadays. The widespread adoption of fine thread profiles also means that less torque is required for a given degree of tightness which suits the limited capability of open ended spanners.           
                 


Title: Re: Aprilia engine rebuild.
Post by: ben on 12 June, 2018, 08:45:18 PM
I am now happy to report the Aprilia is back on the road with loads of oil pressure and no smoke.

I won't know how well she goes with her Fulvia pistons until I have given them a chance to bed in but for a first gentle trip we gate-crashed the SPR on Saturday evening and all seems well.

As an added bonus the clutch is a lot less juddery than it used to be. I was surprised as it is an S1 version with the hairpin springs whereas I was previously running an S2 unit with the big central spring.

The first shakedown runs were not exactly trouble free as although the engine started up easily it stopped again about 200 yards from my house and Niki had her first towing experience retrieving me---very shortly followed by her second when I discovered it was not a simple case of running short of fuel as I had wrongly diagnosed.
It was a fuel issue however.The pump was providing enough for starting and good tick-over but not enough to give any power.Fitting a spare pump was the cure.It seems that the push-rods in the replacement engine pump mounting were a little bit shorter than those that were fitted in the old engine.


Title: Re: Aprilia engine rebuild.
Post by: davidwheeler on 18 June, 2018, 07:33:08 AM
What oil are you using?  Mine spends almost all its time hard on the top stop except at tickover on 10/40 semi-synthetic - after two years hard use.
Smooth engine with the Fulvia pistons?  They must be the same weight as the originals?