Balancing

[les]

I am planning the building of a 1275 ital unit I've had for years ( always other things getting in the way) and looking on the osselli engineering site some interesting stuff. To balance the whole assembly is around £240 which I though wasn't a bad price, I want the rods done definitely but at that price I am thinking do the lot. Am I going overboard for this engine or would it be money well spent?

[philthehill]

Les
If you want the engine to last and be smooth - all of the reciprocating and rotating parts should be balanced.
The price is competitive but do not forget the VAT which will be on top of that £240.
Oselli did the balancing of my 1380cc engine and I was very pleased with the result.
Prior to Oselli moving to Great Horwood (between Buckingham and Milton Keynes) they have over many years done all of my machining work except the special 7 port 940 head.
The spare 1400cc Midget engine I have was offset bored by Oselli and they did the modification work on the three Midget crankshafts I have available. They also made the lightweight steel flywheel currently mounted on the 1380cc.
For their work on my 'A' Series I would highly recommend Oselli.
Talking of crankshafts I would recommend replacing the Ital crankshaft with the 1275cc Midget crankshaft including the rods and pistons also the flywheel from the Midget. It is a straight swop.
The Midget crankshaft is a much better and stronger crankshaft (EN16T heat treated was originally EN40B & Nitrited) which does not suffer the problems which may be encountered with the Marina/Ital crankshaft i.e. poor rolled fillets between crank journal and crank web which can lead to cracking and crankshaft failure.
Phil

[edd_barker]

The next time we are all reading about an event that 'broke the internet', it won't be a Kardashian, it'll be Phil listing his stock of unique spares on eBay!

[philthehill]

[les]

Thanks Phil, don't know how far I want to go regarding changing to midget parts, your advise is sound but doubt I'll be using the engine to the degree that would warrant it. It will be going in my van and the main aim is reliability and smoothness. However you've now given me another issue to consider ! ---------If I'm coughing up for balancing (plus vat) it would maybe make sense to do it on the best assembly! No wonder this project keeps getting put back!!

[philthehill]

Les
If you only want to balance the rods - why not do the static balance (comparing and adjusting big end/bearing caps and little end weights until all four weigh the same) yourself?
For your intended purposes the static balance will be more than satisfactory.

The task is quite simple but time consuming.
The use of a 1/2 gram scales (with a zero facility) and a pair of home made knife edges is more than adequate.

Phil

[les]

That's great Phil, in fact I made up a jig very similar but the pivot point had too much friction to rest in the same place twice, I had thought of incorporating a ball race as the pivot but having seen your picture using a gudgeon pin with its fine finish, looks like that's the more straightforward way to go!, thanks.

[philthehill]

The old gudgen pin lightly oiled fits the bill nicely.
The other end is easier as I just put the knife edge between the cap and the rod.