minimum acceptable height of a yb cylinder head
#1
minimum acceptable height of a yb cylinder head
Hi guys
on the look out for a new 4x4 cylinder head. looking at a few used ones but need to know the bare minimum i should accept for height? been told original factory height was just over 139. Norris motorsport site says not to use less than 138.63.
I do however have 4x4 male pistons with cut outs and a tiny skim off the top..
so with my set up what you guys reckon?
Cheers
on the look out for a new 4x4 cylinder head. looking at a few used ones but need to know the bare minimum i should accept for height? been told original factory height was just over 139. Norris motorsport site says not to use less than 138.63.
I do however have 4x4 male pistons with cut outs and a tiny skim off the top..
so with my set up what you guys reckon?
Cheers
#3
Hey mate,
Try this link....,
http://bbs.rsownersclub.co.uk/showth...head+thickness
They basically say:
The thickness (from block gasket face to top of head where rocker cover face is) should be:
-139.2 new
-137.6 is a point at which you are run a risk of valve seats clashing as there's so little material left around them. Manufacturers minimum recommended thickness is 138.68mm
-On the forums there is other people running*138.3mm but all accept there's a risk involved. anything beyond that and the head either should be used for a N/A application or discarded
Try this link....,
http://bbs.rsownersclub.co.uk/showth...head+thickness
They basically say:
The thickness (from block gasket face to top of head where rocker cover face is) should be:
-139.2 new
-137.6 is a point at which you are run a risk of valve seats clashing as there's so little material left around them. Manufacturers minimum recommended thickness is 138.68mm
-On the forums there is other people running*138.3mm but all accept there's a risk involved. anything beyond that and the head either should be used for a N/A application or discarded
#4
Thanks for the info.
i took the risk of running an over skimmed head for the past year and its dropped a valve seat and written a piston off. wanted to make sure i didn't make that mistake again!
Cost me a lot but Just bought an unskimmed 4x4 head for peace of mind
Just need to source a single 4x4 mahle piston with cut outs then I'm good to build it back up.
i took the risk of running an over skimmed head for the past year and its dropped a valve seat and written a piston off. wanted to make sure i didn't make that mistake again!
Cost me a lot but Just bought an unskimmed 4x4 head for peace of mind
Just need to source a single 4x4 mahle piston with cut outs then I'm good to build it back up.
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