Technical Death Rattle!!!!!!

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Technical Death Rattle!!!!!!

Ian - You show outstanding persistence - I would of junked the barrels and pistons by now
Now you need to find out.....
 
Ian - You show outstanding persistence - I would of junked the barrels and pistons by now
Now you need to find out.....

Hi Andrew, yep it's like an itch that you can't quite reach!!!! Now that I am 90% sure of the barrel origin I'm 90% happy - if that makes sense??? I'm also told by my engine man that the pistons (126BIS) are ok to reuse just needing a quick surface polish where the scuff marks are (anyone needing some 80mm BIS pistons P/M me please) After all that has gone on it's likely that some 80mm barrels have been put together with 80mm pistons of differing makes and they have not made anything like matched set, the engine has run well enough, but then the point came when the shoddy build became apparent. The piston to bore clearance was miles out when they were measured!!!!!

Ian.
 
So is your engine a 126 BIS hybrid? I take it that the barrels are going to be matched to the 126 pistons now?
Your persistence is admirable Ian!
Are you carrying out any mods whilst it's in bits?
Regards
Andrew
 
Whoever did that had no idea about engines then Ian.
When I bought new pistons for my more conventional :rolleyes:setup, which needed a rebore, the engineer insisted on having the pistons and then boring the barrels to the clearances to fit. Quite rightly, although I gave him the exact dimensions and oversize, he waited until the actual components arrived.
Most people undertaking this sort of work would know that you can't use unmatched sets from different sources.:bang:
I hope it goes OK from here...you deserve it for your persistence.
 
Peter, Andrew, thanks for the positive comments - appreciated. Yes it is a BIS hybrid with the odd panda 30 part too!! With the new pistons (80.4mm) my engine man will measure and then bore and hone to fit with the correct piston/bore clearance. I can then reassemble and run in gently!!! The only extra mod I am finishing at the moment is the fitting of an oil cooler fan, it will be fully automatic in action and will help keep temperatures in hand. (pics to follow)
I am seeking info on crankshaft type(s) flywheel type(s) and weights along with balancing, with the aim of building a new fast road engine based on a new crankcase, steel bearings, balanced crank and rods/pistons, slightly lighter (balanced) flywheel. An Athena kit will provide a lot of the parts required and then I shall top it all off with my other more extreme panda 30 head and a solex 35 phh sidedraught carb. It will probably be a long term project we shall see how things progress.

Ian.
 
The next engine sounds like fun. I've fitted my oil cooler under the car - it will be interesting to compare running temperatures
There is a rumour that the BIS crank is the one to go for - but have yet to read any quantified reason behind this.
I was advised against a super lightweight flywheel as the inherent imbalance of a two cylinder engine / racy cam - makes for an intractable engine
Mine is 4kg and has a gearbox support and will have a cylinder head damper to help. Uprated and balanced clutch is also fitted.
Thing is .....how far to go.....how far is far enough?
 
Ian;
Have you bought your 'next engine' crank-case yet? if you haven't, there is a very good chance that I will have a complete 126 (652cc) engine for sale (at a very sensible price!). It is a 'project' engine in that it is complete, but will need a good clean-up. It is one of the 5 (126, 652cc) engines I have in my workshop at the moment--1 in the car, 1 on my rotisserie and the basis for my next engine (also based upon an "Athena" kit) and the 3 that I have undertaken to build 1 good engine out of. Flywheel-wise, a standard 500 flywheel will fit and is about as light as you want to go for a ROAD engine. I will have a word with the owners of the 3 engines and see what they are wanting for them.
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Greetings All, I have at last heard back from the USA and 'Aircooled.net' (it only took a month!!!):eek: the spigot measurement of their upgrade kit is 85.2mm - my very rough measurements of my barrels gave me 84.73mm so there you have it!! I am now putting this question to bed!! Still no news of impending arrival of my parts (it's beginning to do my head in!):mad::mad: the most I can find out is that they are on the way in a container of other parts and given the delay (3+ weeks) they must be coming by sea. Yes, I know the members here are probably muttering that it would have been better to order them individually from Italy, but this has all been arranged by my engine man so need's must I suppose, I'll get back when the parts land.

Ian.
 
Greetings All,

Just heard back from my engine guru with the following news. The cylinder bores are 5 thou oversize - in metric speak that's a bore of 80.13mm. The piston to bore clearance is 10 thou - or 0.26mm. My man says that this is excessive and may be part of the overall problem. There is a distinct possibility that the cylinders have been badly bored out (I suspect from 652) and 80mm pistons put in with a resulting minimum of wear life before trouble. The original pistons are 'Hepolite' and are listed in the catalogue, so after a check and measure of the cylinder wall thickness (rebore?) we may be able to find a piston to fit correctly??? Or it's a new barrel and piston set to purchase?????? I'll get back with news when I know, but it looks like a classic example (bad) of an engine being thrown together rather than built correctly!!!!!!!!!!!!

Ian.

Greetings all, just a quick note to finish this thread as I have noticed on the 'Athena' 700cc kit literature that the piston to bore clearance is from 0.06 to 0.08mm which indicates a matched set. These figures are much tighter that the 0.26mm between my parts!!!! I have concluded that my set up has been assembled from an 80mm VW barrel and 126 BIS (80mm) pistons, now you might think that given the figures as stated the bits would fit together well? WRONG I would council anyone who is considering a mod of this type to tread very carefully indeed, and at least measure the fitment accurately to determine the clearance!! Remember Caveat Emptor at all times!!!!

Ian.
 
Halleluiah!!!!!!!! The Parts have arrived (only took 5+ weeks!!) My engine man has performed a slight rebore and hone to accommodate the 80.5mm pistons. Apparently 80.2 and 80.4mm are not available now. He also says that we could have got away with a careful hone only (80.15 to 80.50mm) but this way at least the bores are now straight and the piston to bore clearance is now correct. The pistons are Italian but have no markings and am in the throes of getting an answer from the supplier. I have the advantage of more capacity too up from 704cc to a mind numbing 712.54cc !!! Damn the car will positively fly now!!!! I have also been checking the deck clearance and found that the piston crowns the cylinder top by some 0.64mm, and having looked at the published figures for the multitude of 700cc kits around find that a figure of 1.0 to 1.3mm seems to be the recommended clearance between the piston top and cylinder top. So I shall adjust either the base support plate or gasket to achieve this. I also note that the Athena kit quotes a combustion chamber volume of some 37cc to achieve a 10.3:1 compression ratio and as my heads are 34.2 and 35.7cc's I shall have to factor this too as I want to run at approx no more than 9.5:1 to start with. I'll get back with progress.

Ian.
 

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Have found that the new pistons are from CPS in Turin Italy (Costruzione Pistoni Speciali) they can supply items for the 500 from 73 to 86mm and are very shiny!

Ian.
 
Greetings, Parts arrived from AG today including an 85.5mm x 1.0mm steel base plate. This has had the effect of adjusting my required figures and added to the strength of the assembly. My adjustment has now given me the following -
80.5mm bore x 70.0mm stroke. 0.50mm copper gasket and 34.20cc cylinder head. The piston top to barrel top clearance is now 0.7mm and all this gives me a C/R of 9.83:1 if I remove the copper gasket I will immediately arrive at 10.43:1
If I use the other head with 35.7cc capacity I get the following - 9.52:1 with the gasket and 10.07:1 without. So now It's make my mind up time!!
Pic's to follow assembly.

Ian.
 
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Greetings, during the pre-build fit up I have discovered that both of the head gaskets I have available are a poor fit and in places intrude into the cylinder. Now, I find this a bit disconcerting as the 0.5mm item (used as a pattern for the 1.2mm item) is produced by "Guarnitauto Italy" and they produce the well known 'Athena' tuning kit for the 500/126 engine??? I appreciate that this kit runs without a gasket, but surely these third party parts should be a better fit?? :confused:Or do I just get my files out and make the required adjustments?? Any recommendations people?? Maybe I should just run without a gasket???:yuck:

Ian.
 
i've never got to open a motor, yet, but if that would happen to me, i'd rather use a hobby knife to cut the extra without the risk of damaging the border of the cylinder with files.. even the thinnest sounds too abrasive to me..
 
Well, am I cursed or what? After approx 6 months of enjoyment running the car in and enjoying the country lanes, roof down, windows open and some Italian Opera on the stereo IT'S BACK:eek::eek::eek: Driving over to a mate the other day , taking my time never more than 4,800 rpm (approx 60mph) and then I heard it - "Oh S**t" whats that noise:mad::mad::mad:it sounded like a tappet at first (I fool myself) but by the time I got home - 5 miles, my hearing had accepted that I had ANOTHER rattle:bang::bang::bang: After switching off I sat on the drive wondering what I had done wrong to offend the engine gods???
The next day I dropped the oil and sump to check the bottom end - nothing obvious and the magnetic plug was not contaminated:mad:removed the lower big end caps and noticed very slight marking on the number 2 journal (can just feel it with a finger nail) number 1 ok, but no knocking(y) gave the rods a good to and frow and also no knock(y) bores look good(y)but when I put the car into gear and hand turned the crank until it locked up and then turned it back slightly there the little S*d was just a tap felt through the flywheel:mad::mad:
So it's engine out (again) and check the main bearings:mad::mad:
I've always been careful, checked the oil pressure and temp and still this. I think that fundamentally these engines (especially old ones) will not tolerate much extra power from tuning unless everything is new and that's where I have come unstuck - Bugger(n)(n)(n)
Ian.
 
Ian - Sorry to hear of your woe!
I haven't been made aware of tuning related "fatalities" as common as you are experiencing.
I guess all you can do is strip everything down and inspect and measure all components.....
The stresses that a mild improvement bring really shouldn't cause such problems.
Has everything been balanced properly?
I believe the original "redline" was 4700 revs....with a balanced standard crank you should get reliable 6000/6500...
Maybe worth getting internals checked for trueness. Crank "whip" would eat main bearings as would a conrod/ slapping piston.....
I know you know all of this....just trying to assist diagnosis.
Andrew
 
Commiserations from me too Ian. :cry: Obviously no-one can offer anything other than guesses at this stage, but I would suggest somewhat the opposite to what you surmise. I think that whenever you introduce a new, after-market engine component there is bound to be a risk that it is not made properly.
Generally I have found that the original engine bits are superbly made and very resistant to wear. (Perhaps I should add, apart from the valve seats? ;). ) But as soon as you have machining done on them then you're back with that potential for incorrect dimensions and clearances or horrible grit or metal fragments floating about.

It sounds like you may have a loose main bearing or flywheel or the big crankshaft nut that takes up the end-float.

Whatever the cause I hope that it's quick and inexpensive to sort out.(y)
 
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Thanks Gents, all appreciated. I'll be sure to check the parts you indicate Peter - anything to get to the cause:( As my car has a 126 derived engine I'm happy that the rev limit has not been exceeded and I know that the Panda 30 engine (652cc) gave it's nominal 30bhp at 5500rpm without any special balancing. But I will endeavour to get full balancing done this time if only to assist with longevity. I may even canvas the engine builders around and get a quote for another engine, I will do some figures covering the full cost of any work to be done and see how it all compairs, but It will be an arm and a leg for a new item:eek::eek::eek:

Ian.
 
I think I've found the problem(n)(n)(n)Took the head off and saw the bore marks - only in the number two (front) cylinder. Four equally spaced vertical scuff marks two on each side of the bore:eek::eek::eek: Methinks I'll be having a personal chat with my engineer about this as the rebore with new pistons was only a few months and some 300Km ago:mad: I will say that the engine has been running great with good oil pressure and temperature, and then suddenly this - bugger!! The pic shows both bores with and without the marks, any clues people???

Ian.
 

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