The Rebuild Begins

[MK1_Oz]

Cheers Warren for the offer and subject to the following I may need to PM you about it. I don't do things cheap but just whinge every time the wallet comes out!!! hehe

I have just checked the dummy build block I have. It is.........90.8mm and does not feel to have a lip at the top of the bores!!! It also has a height of 221mm (measured at the back of the block from top face to the sump mounting face) whereas my 205 block is 220mm high.

This old block has some surface rust in the bores so I am really not sure if that would clean off with a hone or not. Thoughts on suitability?

Block4_111212.jpg (84.44 KiB) Viewed 13656 times

Block5_111212.jpg (99.42 KiB) Viewed 13656 times

I also do not have the main caps for this block. I guess the ones from the 205 block will be fine but would need a line bore?

Then there is the $200 Farcebook motor that the boys put in for the last day. No idea what that block is like at this time.....

[Warren Heath]

[Danny M]

Loose oil line will have done the damage
Move tank forward so that you can mount it higher and straighten out the oil lines so that you haven't got that silly high point

[MK1_Oz]

So you don't see signs of detonation Danny?

I have had it suggested to me that maybe I should bore out and reline no4 back to 92mm. That way the cost is minimised (until I can afford a full new block) as I only need to buy 1 piston. Thoughts? I assume relining is possible with these blocks and cannot see why it would make a difference if only 1 cylinder was done.

[Danny M]

Why does the piston need replacing

[MK1_Oz]

Good question....glad you asked......ummm dunno. Just assumed that given the bore scoring that it will also be messed up. Will pull it out later to see. If it doesnt then I suppose I could get away with a re-line only???

[PaulMK1]

Nobody can make that call based on those pictures....

Take it to a reputable engine machine shop get them to measure it all up and you maybe lucky and get away with a hone and a crank grind.

Paul.

[Warren Heath]

[MK1_Oz]

Pulled the offending piston out this afternoon. The skirt of the piston has some scoring marks on it but they are not terribly deep. Barely catch my nail. Hopefully the engine guy will tell me its ok to reuse.

The offending bearing (I know this stuff is all been there done that for you guys but its great learning for me!!);

Bearing1_121212.jpg (82.17 KiB) Viewed 13580 times

What is the deal with the worn area on teh side of the bearing? Not looked at a new bearing but obviously they have sides on them?

Bearing2_121212.jpg (83.72 KiB) Viewed 13580 times

The rod is very burnt but is still smooth so again hopefully a hone/polish should see it live again (unless the engine was detonating in which case it needs to be checked for straightness!).

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Rod2_121212.jpg (95.97 KiB) Viewed 13580 times

[MK1_Oz]

Now the bit I really couldn't work out is the crank journal. Unfortunately there is one small score in it so again fingers crossed it can be re-ground and saved (not sure if there is any reason why a crank should retain standard size journals for competition or not). The bit I am confused about is that on the sides of the journal are around 3mm wide and 1-2mm deep channels all the way around. Is this part of the standard treatment to a crank (radiusing the edges to reduce cracking) or is this wear that the bearing has done?????

Crank1_121212.jpg (87.78 KiB) Viewed 13580 times

Time to box it up and take it to the pro...........

[PaulMK1]

That crank will need a regrind and whenever you spin a bearing you need to get the rods resized.

If you pull the cap off one of the other "good" rods and pull the bearing you'll be able to tell what size bearings you have. Hopefully they are standard or first oversize and you have plenty of meat left for oversizing.

[Danny M]

crack test and stress relieve the crank
What are the marks on the rod ends and rod caps around the bolt holes

[ozstang65]

[George&Kez]

^^ +1 Looks like there became enough gap to start shaving the bearing.

(Excellent thread)

[MK1_Oz]

[PaulMK1]

Exactly right - similar to line boring the block. To "resize" the rod they shave the cap and the rod faces then re-bore to the new (or original) size.

How long did you run the engine with the stuffed bearing? that "good" rod bearing looks like a fair bit of rubbish has been dragged through the oilways.

[MK1_Oz]

We lost power half way through a stage then a few kms later at the end of the stage realised the engine was knocking. The 'good' bearing is still smooth to touch but obviously has those marks on it.

[MK1_Oz]

Just been down at the engine builders having a chat about options. Seems a likeable fella (big plus in my book)...

To prep my spare standard block (bore to 1st oversize which he says is 1998cc???), hone, line hone, acid wash etc is ~$650 + a set of pistons ~$700 =~$1350

To put a liner in just the knackered cylinder of the 205 block is ~$250 + no piston purchases (providing old one is still OK)

Then rebuild labour and bearings etc.


Will see if he is still singing the same tune once he eyeballs the parts. If he is then I may take the cheaper option for now then as funds become available during next year build up the spare block.

He reakons you cannot buy single pistons in Australia anymore but then I would probably find somewhere OS to source them from anyway. He also was saying that I should take the CR back to 10.5:1 which he claims is definitely safe for 98 octane. It's an option or I could rely on the addition of octane booster (approved) from now on to take 98 up to 100 octane.

[jpayne]

OZ,
is the engine builder Chris milton as earlier posted? If so I have heard good things about him, never had work done , never needed it, but I believe he is the only one in SA that has a Pinto boring brace? plate? thingamyjig.
He alsois a 5 minute walk from where Im living...

Justin

[MK1_Oz]