head gasket

[mr white]

well was planing on getting the car sorted for pod next month and serviced it yesterday then my bro rung me up and said lets go southend last nite so went and ended up doing my head gasket on the way back with loads of smoke on the m25. well ive striped it down today and found its 2 water holes between piston 1and 2 and 3 and 4 thisis my fourth time im changing the head gasket so im used to it but i always noticed its this point that always blows because its the closest/weakest point of the firing rings anybody else noticed this and what can be done to prevent this apart from running less boost was running around 22psi manifold with 11.4 afr wot

[Markey Mark (BD)]

The first thing to do mate is work out why its blown the gasket again before you can work out how to prevent it.
Do the fire rings look egg shaped at all on the old gasket or any signs of pitting on it or the piston tops?

[mr white]

il try up load a pi but the center 2 firing rings are defo egg shaped and the pistons dont have any visable det marks, but what looks like some lime scale though where i drove it/costed it back home smoking

[Andrew Cooke]

got a pic of the head showing combustion chambers?

fit the bolts into the block and check that you can screw them by hand further than they need to go to clamp the head.

[mr white]

it had a rebuild just over a year ago now had new pistons liners rings havent got any pics of pistons from today though, bolt holes were cleaned out when i rebuilt it and chased out with a tap and no fluid in them either. when taking the head of today though i noticed at the water pump end, the rocker shaft part the bolts down has cracked where the bolt goes through, and broke of. but didnt come away until pressure was released from that bolt though which had a washer distributing the weight over its mounting hole

[mr white]

havent got a pic of the head but the water hole where the gasket went do look a little coroded

[Alex]

Isn't 11.4 AFR at WOT a little lean? :confused:

[jantheeven]

Isn't 11.4 AFR at WOT a little lean? :confused:

No, that's actually rather rich @ WOT! (lower = richer) You should aim for low 12's...

[Alex]

Of course :cartman: Too early a post for me! :D

[mr white]

well the plugs are a nice grey colour and it flickers between 11.4 and 12 and no signs of det either i always thought people went for mid 11s

[mr white]

well its all back together as of now and running better than before and its ideling better aswell so hopefully will be going pod at the end of the month :)