7 replies to this topic

[cristiano1968]

hello  will be refurbushing my cylinder head 

got new valves springs and guides its  a 998cc head  lead free   1989 998cc engine  

what is the hight  of the valve guides or shall i just measure the ones still in the block 

ive got them from mini spares says 

0.550. fron top to seat  

[MiNiKiN]

14.86mm if I remember correctly. But that's on my 12G940 - so I hope someone will know better.

What shall be checked before (as I found out after fitting the guides ) is to check the valve spring seats are evenly recessed. On my head they had a depth variation of up to 1.2 mm !!!

[coopertaz]

fitted mine to same depth as old ones i removed.also needed to ream very slightly after fitting

[cristiano1968]

Yes I'll get the machine shop do that

[nicklouse]

Yes 998 and 1275 head have different numbers.

 

can’t remember of th3 top of my head what they are but I think AC posted them a few weeks back.

[Spider]

There is an early and a late Spec for these. The changeover was somewhere around 1978-79-ish.

 

It's 0.540" (13.72 mm) for the late heads.

 

[cristiano1968]

Oh that's great that pic.
Where did you get that from?
I'll print it and take it to the machine shop
Thanks 😊

[Spider]

Oh that's great that pic.
Where did you get that from?
I'll print it and take it to the machine shop
Thanks

 

Factory info !