I'm going to need to deck the block, aren't I?

[Adoom]

So I blew the head gasket on THE STARVIA, (CA18ET) some time ago.
I ordered a Cometic head gasket to replace it. It's coming from the US. Should arrive in about a week now.
I finally got around to taking the head off today.
The gasket was pushed out about 1.5mm and blew between #3 and the water jacket.
After cleaning it up a little, there is a little dent in the block where it blew....
I guess we have the reason for failure.




Spark plug did not like that!

So I guess I cannot get away with not machining the deck Even with my awesome head gasket, it's just going to blow through the same place again...
So I have the strip the block completely, right?
What can I reuse, and what do I have to replace?

[holden_fan2005]

I would of thought cometic gaskets would be more picky about two perfectly flat surfaces than a regular composite gasket??

[Dell'Orto]

Yup MLSR gaskets need a good surface. What is the head like in that spot?
Time for CA18DET perhaps?

[Adoom]

Yup MLSR gaskets need a good surface. What is the head like in that spot?
Time for CA18DET perhaps?

The head looks fine. But I have not cleaned it up properly and gone over it with a straight edge and feeler gauges.

In fantasy land where I have a lot more disposable income, I would build up a CA18DET.
But, it's not really an option.
I don't have a suitable DET(I have a 1st gen, in bits, but the head/inlet manifold is the sucky version).
I would need a new tune.

So.
Do I need to strip the block bare?
I guess I just need a gasket set? The bearings can be reused if I keep them in the right order?

[Adoom]

Cleaned it a bit...
Aaaaand....
Spark plug electrode on #3 and #1 are well melted. Ignore the plugs with no electrodes. They are blanking plugs from the original twin spark set up.
Also bits of alloy missing from around the plug holes. This may be from when they were helicoiled years ago. I'm not sure if these were the helicoiled ones.


#2 and #4 are fine. No damage.
The cylinder head still seems to be flat, I used a razor blade as a straight edge across where it blew. No gaps.

But then. I turned the engine so I could clean the rusty coolant stuff out of cylinder #3.






I can feel that it's rough with my fingernail.
#1, #2 and #4 cylinders are fine.

FUUUUUUUUUUUU!!!

So, could the blown head gasket be the cause of these melting electrodes, or could the cause of the blown headgasket also be the cause of the melting electrodes?

[Grotty]

Hey, you'll need to deck your block for your new headgasket and i'd say hone the cylinder's for best out come at least.

[92mr2paddy]

this might be a stupid and unrelated question but how come your pistons have 4 recesses for valves but the head only has 2 valves??

[Adoom]

this might be a stupid and unrelated question but how come your pistons have 4 recesses for valves but the head only has 2 valves??

I dunno, they are all like that.. Maybe they were planning ahead? But they ended up using different rods and pistons in the 16 valve anyway. 8V uses pressed gudgeon pins, 16V uses floating. Probably other differences too.

[QikStarlie]

looks like detonation, caused both the melted plugs and the bhg. likely too much ignition advance and the plug would be a hot spot.

[Adoom]

looks like detonation, caused both the melted plugs and the bhg. likely too much ignition advance and the plug would be a hot spot.

Yeh. I could theorise that there is uneven fuel distribution to the cylinders due to the extra injector(for E85) being upstream of the throttle body causing some cylinders to lean out.... maybe. While the E85 is being injected, the 95 octane, from the normal injectors, is reduced and the ignition timing increased.

[touge_ae101]

Throw it away. Start again. Need more valves. Start with 20 that should do it fine.

my 2c

[Adoom]

Throw it away. Start again. Need more valves. Start with 20 that should do it fine.

my 2c

That's the plan.... but only 16. I got a CA18DET with a bottom end knock. Technically, I only need the head, I already have a DET shortblock in parts. But if I'm lucky, it just needs a set of bearings.
But I'd still like to know what caused it to detonate.

[Dell'Orto]

Probably the tune. Any idea of intake air temps at the time?

[Adoom]

Probably the tune. Any idea of intake air temps at the time?

Unless the link has onboard logging that runs by default. I have no idea.

<EDIT>
It apparently does.... Haven't looked at it at all though.

[Adoom]

The logging has to be turned on before it will start logging... I'm pretty sure it's not.

[Stu-]

Don't you have water meth setup?
I'm wondering if its stopped for some reason causing fun times inside the engine?

[Adoom]

Don't you have water meth setup?
I'm wondering if its stopped for some reason causing fun times inside the engine?

I used to. We changed it to an auxiliary fuel system and a single injector with E85 to do basically the same thing as water meth injection. I think the E85 was just not being evenly distributed to the cylinders, so some cylinders went rich and others went lean and detonated.
Or the injector got blocked from something in the line after the filter...

[QikStarlie]

tbh probably best to remove that extra injector e85 system. likely not getting an even fuel mix across all 4 cylinders as you say. plus as stu says; if it fails to turn on for any reason, you're left with a fuel mix thats likely going to melt stuff. running better fuel though the main injectors is a safer option.

in saying all that. the setup may have been working fine, but junk tune. too much ignition advance is the usual cause. or wrong afr