Cam bearing shell?

[kwijibo_coupe]

Hi guys,

Last weekend I managed to break one of the cam bearing shells on the G40 (the bit the rocker cover screws into).
I have access to a Mk 2 coupe S engine and a Mk3 1043cc AAU engine. Would the same cam bearing shell from either of these engines be ok to fit onto my G40?

Cheers.

[Dan]

It might be the same type of bearing cap, but it won't be the same size or position that the one off another head is on. They are machined in situ.

Do you have access to bore gauges ? I would suggest looking at which relevant spare heads cam cap (i.e. cap no.) is similar or oversize so it can be machined to yours. It will need align boring and possible align honing to size. I would suggest contacting an engine machine shop.

[hayesey]

yes as Dan says they aren't really interchangeable.  When the heads are manufactured the caps are torqued down and the whole lot line-bored in situ.  This means that only the caps from the original head will properly match the bottom half of the bearing which is part of the head casting.  You might be able to find a spare which is close enough.  When decent ones are torqued up (with no cam in) you can't feel an edge where they meet with your finger, if you put ones on from another head you'll probably be able to feel an edge.  I'd say if you can find one where you can't feel an edge then it'll be OK to use.

[kwijibo_coupe]

Ok cheers for the replies guys, I'll try and find a match today.

Next question...what could have caused this? It happened after a short spirited drive on boost. I lost some power and saw oil vapour coming from the bonnet, opened it to find oil coming from the rocker cover where the bearing cap had split.
Any ideas?

[hayesey]

possibly someone already has put a non-matching one on!

[kwijibo_coupe]

But its not the part the cam runs in thats broken off its the threaded part the rocker cover bolts into...as if its tried blowing the rocker cover off.

[hayesey]

ah right, perhaps it got cracked by over tightening the bolt?

[kwijibo_coupe]

Changed it and now the car sounds rough as fook!! Almost like bottom end knocking, would a badly matched cap cause this or would it actually be the bottom end?

[lance]

yake it off and try again i would say its too tight and fucked your cam now.