exhaust leak +1 

If it is louder and more evident when you tighten up the extractors and sounds like a ticking sound that is more evident under throttle /load, it really sound like exhaust (pardon the pun)...  It could be a hairline crack in the extractors, that when you tighten them, it opens up more....  Or a dud extractor gasket that is leaking too...
 
The more an extractor is cracked, the worse the sound becomes and the engine also goes off song too... My race car broke #1 pipe on the extractors at Sandown 2 years ago, and in the distance of the main front straight, it went from sounding like a cracked header, to fully broken off and significantly down on power... Backed off and idled back to the pits... The pipe had broken off totally (100% around) and was about 5mm out of alignment....  Had to drive it home with a Coke can clamped around the extractor pipe and it sounded like a tractor and ran not much better than one.  Sounded like a cracked extractor, but 200 times worse..... They start off small, and sometimes un-noticed, but it will get worse till you can hear it idling and then feeling a power loss if you still do not fix it...

Hey guys so after finally getting a compression tester that works (and $50 later) i've found that number 1 and 2 cylinders have no compression whatsoever... Take the head off and the gasket has blown between number 1 and 2 cylinder....


 
 
 
so what I was wondering is, whats the cause of this??? I torqued the head bolts as specified in the workshop manual after 15-20mins of idle when first assembled... Could this just be a dodgy gasket? The engine has only done 4000km's so I'm a little bit confused... Also, I noticed that there is similar wear in the gasket between cylinder 2 and 3, is this gasket not suitable..?
 
Thanks guys!

Haha sorry mate just went back through the comments and realised that was your initial diagnosis, thanks   i was a little too busy checking exhaust leaks 
 
Yes the block was decked and the head was faced 4000km's ago at rebuild. I've just remembered something from assembly. My mate who helped me reassembled neglected to use the grease that came with the head bolts when assembling... I've been reading up on the inability to correctly torque down stretch bolts if the correct lubricant isn't used... so i'm thinking..... incorrectly torqued down head which caused the head gasket to be incorrectly compressed, hence allowing for that weak spot to blow? would this be consistent with the 2/3 cylinder barrier about to go aswell???

Not sure what you used but also make sure you use quality head gasket !

Cheers

I'm with Rs2000.
Do a compression test for a breached gasket.
If its not timing then it's likely hot or lean.
Is plug colour ok ?
Advance hose ok?

obsesscort

hey RS2000, i've cleaned the block and head surfaces down with carby cleaner and really fine grit sandpaper and block. I've checked the block and head surface and i can't fit a .05mm feeler gauge anywhere with the bar from front of block to rear of block, so thats looking OK. I also used a industrial vac and got anything foreign out of all the bolt holes and piston bores (even though i covered this with a rag whenever possible).


are you referring to timing when you refer to checking the "tune" after installation is complete?

i might just take this time to add some keywords to this post for future sufferers....
correctly installing head gasket
correctly installing head bolts
problems with compression


thanks again for your replies guys

You obviously got away without head and block surface damage, cast iron is forgiving, had it been an alloy head would have been a decent crater there. 
Sorry but vacuming the bolt holes is not good enough. Tap is the only way to make sure the threads are clean. Sounds like you didnt use a tap at rebuild either?
Do yourself a favour and buy a tap, they not expensive.
 
Yes definately recheck your tune- mixtures and timing, making sure the advance curve, and total advance is suitable for your setup.
 
Cheers