Opel Monza 3.0 Rocker Arms

[SambaS]

Is there any right or wrong way to tighten these?

I had one snap and had to replace it.

Noticed some seemed loose where others didn't, tightened all up.... engine wasn't happy.

Backed all off and now it seems fine.

[bstardchild]

Jan 17, 2015 12:32:03 GMT SambaS said:

Is there any right or wrong way to tighten these?

I had one snap and had to replace it.

Noticed some seemed loose where others didn't, tightened all up.... engine wasn't happy.

Backed all off and now it seems fine.

Very much a proper way - cyl where you want to check rocker clearances needs to be at TDC

Rule of nine cuts down the time it takes and the number of engine rotations by hand

[reliantscimitar]

hi there

aren't these fitted with hydraulic tappets ?

tighten them down until free play in the arm has gone and then 1/2 turn to preload the hydraulic tappet.

when the arm / valve is in the closed position.

Cheers - mike

[SambaS]

Yeah hydraulic, I just tightened it up so the bolt position looked like the other 11

[bstardchild]

Jan 17, 2015 14:34:56 GMT reliantscimitar said:

hi there

aren't these fitted with hydraulic tappets ?

tighten them down until free play in the arm has gone and then 1/2 turn to preload the hydraulic tappet.

when the arm / valve is in the closed position.

Cheers - mike

That should result in all the valves burnt out in fairly quick time

[Bozwell]

why's that?


hydraulic tappets have preload.

probably whats happened is the hydraulic tappet pumped up due to broken rocker. they take a while to bleed down again so may be rough running for a while after adjustment due to the valve being held open.

as said get the valves to the closed position and then set the rocker preload.

if in doubt consult a workshop manual.

[bstardchild]

Jan 17, 2015 20:23:06 GMT Bozwell said:

why's that?


hydraulic tappets have preload.

probably whats happened is the hydraulic tappet pumped up due to broken rocker. they take a while to bleed down again so may be rough running for a while after adjustment due to the valve being held open.

as said get the valves to the closed position and then set the rocker preload.

if in doubt consult a workshop manual.

Sorry - not all Monzas have heads suitable for unleaded

- set the clearances for a unleaded head and everything is fine as there is no valve seat recession

- set the clearances for a head that's not suitable for unleaded and you will get some valve seat recession over time

If you get valve seat recession you'll get burnt out valves

That's why I'm not to keen on full pre-load on hydraulic tappets in CIH engines

[Bozwell]

you've lost me. is it clearance or preload?

[bstardchild]

Jan 19, 2015 21:42:25 GMT Bozwell said:

you've lost me. is it clearance or preload?

On unleaded heads - preload - up to 1 turn

My caution with this is because there are a lot of Monza 12V CIH engines that don't have hardened valve seats

On leaded heads - I'd want as little preload as I could get away with - simply because valve set recession is gonna add to the pre-load

If it rattles like heck then you have clearance but don't assume just because they are hydraulic tappets that winding in a turn of pre-load is a great idea

[Bozwell]

your still confusing me with your description.

so your saying put in a tiny amount of preload to take up any valve resession which will cause more preload, yet valve resession is caused by preload?


i think i know what your trying to say and saying clearance really confused things where i guess you mean a little preload or standard/a lot of preload.


i can't see that valve seat resession is caused by the hydraulic tappets though. i would say going by your description the hydraulic tappets are preloaded less to compensate for a longer time for valve seat resession before the tappets bottoms out .  

[bstardchild]

Jan 20, 2015 0:01:25 GMT Bozwell said:

your still confusing me with your description.

so your saying put in a tiny amount of preload to take up any valve resession which will cause more preload, yet valve resession is caused by preload?


i think i know what your trying to say and saying clearance really confused things where i guess you mean a little preload or standard/a lot of preload.


i can't see that valve seat resession is caused by the hydraulic tappets though. i would say going by your description the hydraulic tappets are preloaded less to compensate for a longer time for valve seat resession before the tappets bottoms out .  

It appears that you can put it into words better than I can