My Monaro rebuild and improve thread

[jet_noise]

On the middle pistons having discolouring:

Isn't that deposits rather than burning?
They'll be running hotter than the outside pair.
Might they be intentionally fuelled a bit richer to help cool?

Wholly speculation on my part IANAM (the mechanic version of IANAD )

[stevieturbo]

mfp4073 said:

Maybe its something to do with the LPG, or issues with the fuel system?

LPG is supposed to be very clean....

The middle two in that photo I'd deem fairly normal for a petrol car.

[marksx]

Here's the other side..





Opened up the underside and flipped. (A surprising amount of water still in there!)

Edited by marksx on Monday 20th August 20:49

Edited by marksx on Monday 20th August 20:50

[marksx]

The windage tray appears to be rusty. Not sure how this could happen without being exposed for a while. Junk it?



Not too much in the sump. Small flakes that are very soft. Bearing? A layer of grey 'powder' in the bottom.

[stevieturbo]

Strangely 2 coloured and 2 discoloured pistons on that side too...although all equally carboned ok.

Bottom of sump would rarely be very clean, wouldn't be overly concerned about that

[Davep24]

Hi,

Not sure how a piece of piston ring can find it's way into the cylinder, the piston to cylinder bore clearances are 1000ths of an inch. The pictures of the damage don't really indicate foreign material either. Looks like they have been hit with a screw driver, as they seem quite regular and similar orientation. Foreign material would be random and more widespread.

Is it possible that the engine has been rebuilt previously? This may account for the clean pistons, additionally one of the cylinders has honing marks again indicating some form of rebuild.

[marksx]

Oddly, you're the second person today that has suggested it could have been rebuilt.

The rod caps have been punched with dots that indicate the cylinder number, so it looks likely that it has been rebuilt.

Raving mentioned to me that someone asked him for pistons for this engine a while ago as two were cracked. He got the pistons but they were never taken. Looks like they got them somewhere else.

So it seems this car is on its second engine, this engine has had a rebuild, may already be honed, has uprated valve springs for some reason, and has unexplained damage to two pistons. Yay.

[marksx]

bd crank bolt! Bloody thing must be welded in!

[marksx]

Finally got the crank bolt out tonight and got the rotating assembly out.

Two types of piston in there, quite a few bearings with significant damage. Some marking on the crank and cam, though I don't know what is normal here.

I took a load of pics. As PH pic upload is toss I've put them in a Dropbox folder....

https://www.dropbox.com/sh/bf02hkpqljl5w21/AABYXvJ...

[bigwheel]

A mongrel motor.
But it looks like light machining will sort it with an obvious cam upgrade.
8 matching pistons would be more reliable! The chances of those pistons weighing anywhere closely similar is remote. Unbalanced rotating assembly

Edited by bigwheel on Friday 31st August 00:03

[ARAF]

Sorry to hear that it's a parts-bin special. I take back my comment from the middle of last month. TunaB strikes again.

[Davep24]

That doesn't look good, I would be fuming if i found that my engine was like that inside.

Have you found out where your oil went yet and are you still planning on rebuilding?

If you are rebuilding have you considered a stroker kit, this would virtually replace all the junk parts (except camshaft) and will give safe reliable and most importantly known power. Wont be cheap though probably looking at over £3k if you do it yourself

[marksx]

I have thought about a stroker. Though I have decided once rebuilt I want the 'cammed v8' sound.

My list was pretty much a copy of MikeyB's car.

LS3 heads and intake, some kind of fancy filter, cam, map, wortec headers, full stainless system.

I gather this is sailing pretty close to the wind with regards to passing emissions. If I add some extra CC into that, I'm guessing I will have to dial back the cam?

[marksx]

I was intrigued so weighed the different piston and rod assemblies.

The 2 with the alternate pistons are 72g heavier than the others!!

These were both on one side of the engine, cylinder 1 and 7.

[Boosted LS1]

I once worked on a nutter engine from a tvr chassis person on here. It has 4 old pistons and rods and 4 newer rods/pistons etc. wker engines and suppliers are definetely out there.

I think the engine came from OZ on the cheap. Why it was a hash was a mystery.

[ARAF]

This is exactly why when I blew ours up at 11,000 miles, we put a new GM crate engine in. It wasn't fair on the car to have people sniping about whether it had/had not been rebuilt correctly.

[anonymous-user]

marksx said:

I have thought about a stroker.

I've had 2 stroked motors in mine and wouldn't if I were you. The first scuffed the piston skirts, the second blew up because the skirt disintegrated at about 6k rpm. You'll need a extended, sleeved block to make sure the pistons are properly supported. Both my stroked engines also used oil too.

[marksx]

wormus said:

I've had 2 stroked motors in mine and wouldn't if I were you. The first scuffed the piston skirts, the second blew up because the skirt disintegrated at about 6k rpm. You'll need a extended, sleeved block to make sure the pistons are properly supported. Both my stroked engines also used oil too.

Heard this from a couple of sources now, so I think I'll shelve that idea. I'm kinda going away from the ls3 top end idea too. Saving some money and working with what I've got+cam.

[stu vxr]

I have and continue to follow this thread with interest, but I have to ask the question is any Monaro given current values worth a engine rebuild or can justify the cost of a crate engine to put back on the road, as a fellow Monaro owner for the past 11 years for the first time ever I honestly don't know or can put a price on our cars.

With the above statement is it honestly worth the effort to rebuild a Monaro with a broken engine given current values?

I personally wouldn't consider a rebuild think my car would be worth more as spare parts.

I would so love to be proved wrong.

[stu vxr]

I have and continue to follow this thread with interest, but I have to ask the question is any Monaro given current values worth a engine rebuild or can justify the cost of a crate engine to put back on the road, as a fellow Monaro owner for the past 11 years for the first time ever I honestly don't know or can put a price on our cars.

With the above statement is it honestly worth the effort to rebuild a Monaro with a broken engine given current values?

I personally wouldn't consider a rebuild think my car would be worth more as spare parts.

I would so love to be proved wrong.