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Messages - hotel21

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General Discussion Area / Re: Working as a film 'extra'.
« on: 11 August 2015, 22:56:32 »
And, naw....  Gave up on porn roles when the birds were older than me.....   :-*

General Discussion Area / Working as a film 'extra'.
« on: 11 August 2015, 22:55:40 »
Sounds a bit off the wall and also teeing myself up for abuse but - anyone any experience of working as a film extra? 

Got a couple of paying leads to appear in films but dunno the ins/outs/payment/etc.



Good stuff Mike. Onwards and upwards!   :y

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 20:34:59 »
This is how I used to measure bore wear........

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 20:28:29 »
Generally speaking, yes, but not all engines are the same.

The ones I cut my teeth on were two stroke diesels that put as much power running backwards as forwards!   ;D

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 20:17:15 »
Side wear is due to crankshaft rotation and crankshaft throw. Combustion pressure is trying to push the piston straight down the bore. The throw of the crankshaft is tiring to turn up and down movement into rotary. It will exert  a degree of sideways-pressure on the  piston on the down stroke and can wear on the cylinder wall.

Wear here can, over time, result in what's known as 'piston slap' where wear is to an extreme and piston is floating about side to side, normally with gudgeon pin wear as well.

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 20:11:34 »

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 20:03:46 »
Honing and glaze bursting are similar but different. Glaze bursting can be done with emery and oil but you have to be carefull of contamination of carbide dust from emery into guts of engine if pistons are still in place.

Honing is generally done with a specialist honing tool with Pistons out.

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 20:00:26 »
Baza - pretty much, yup. Didn't want to go into wear side and ovality too early! :y ;D

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 19:55:51 »
Start with out of parallel.

Pistons are generally very slightly a smaller diameter than the bore. Talking fractions here. The piston rings exert outward force within their grooves onto the cylinder wall. The ring ends when it's assembled, are offset from each other to provide a distorted path for combustion gasses so hopefully reducing blowby.

The outward pressure of the rings onto the bore wall will then wear the outer surface of the rings as the rub on the cylinder walls, as will the cylinder walls obviously. The wear will be non existent above the top compression ring as the compression ring never reaches it and, if the rings do their job, keep the piston central in the bore and thus also not touch the sides. Thus, no wear there.

Below where the top ring reaches will be most wear as combustion gasses try to escape. It wears the side. You have seen the result of a failed head gasket and possible groove cut in head or top of block?  As the piston moves down, pressure in the most general of terms, reduces thus wear is reduced.

Measure the bore in increments from top to bottom and you will see that the extreme top and extreme bottom are basically at factory standard. It increases from bottom to top until it reaches the step created by the top ring.

General Car Chat / Re: Cylinder block theory Q's
« on: 02 June 2015, 19:35:44 »
Here's my understanding, really based on very large, three storey, 2 and 4 stroke marine Diesel engines of a number of years ago.

1). Honing can be used for both roughing and smoothing a cylinder surface. If the bore has been machined (to a slight oversize for example) then honing polishes off the worst of the tooling imperfections. If the bore is well used then the action of the movement and pressure of piston rings polishes and glazes the bore surface such that combustion gasses easily pass by the rings and vice versa, either engine or cylinder oil gets burnt in the process and can gum up rings. Honing in this case busts the glaze on the surface allowing oil to lubricate piston movement as it tends to 'stick' to the honed surface and not slide off the polished bore. 

2). Boring. Is used to either increase cylinder capacity or to return the bore to parallel. Providing the piston, in its normal designed stroke, does not go proud of the block then no adjustment of the head is required. Sometime a thinner head gasket is required to bring back correct compression ratio.

3). Bore measurement. Cylinders can and do become worn out of parallel with the greatest wear at the top of stroke extremity of the top piston ring. Measurement is done so that it can be consider in or out of design tolerance which may dictate replacement rings (they also wear in use remember) or a rebore. If replacement rings then the top ring is generally stepped so that it does not contact the cylinder wall immediately above the compression ring. If it contacts this original bore then it can shatter rings as they are (or were years ago) very brittle. Also it's why you size new rings by placing them in the cylinder and measuring the ring end gap and adjusting (filing) as required.

4). Sleeving. Not something I am familiar with in engines but seen it done in large piston pumps. Any overboring might result in breaking through the cylinder wall so over cutting and sleeving brings the assembly back into spec.

Sorry if a tad long winded but hope you get the gist.


Imagine yourself as either one of life's unfortunates who stuck in a call centre type spam generation empire or indeed, a bot application trying to gain similar entry to oof to flood it with the assorted minutae of Pish that the web is full of....


General Discussion Area / Re: Newent 2015
« on: 27 May 2015, 22:32:47 »
May well have a word with sproglet as he owns my estate now. Might be worth a wee bit of dad and lad time...... :)

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