Hi Guy's

I decided the other day to repalce the head gasket on my EF Falcon. It has 240k on it and was starting to loose coolant into the combustion chamber.

I pulled it apart after much ado and low and behold I thought it had been fitted with 2 gaskets! on closer examination I found that the second gasket was actually a shim of thirty thou or 0.75 mm or thereabouts. It would also see to be a rebuilt engine with 0.03 oversize pistons (30 thou)

The pistons are well within the confines of the deck so I can only presume that the head has been over machined to regain straightness.

My question is, has anyone got the orginginal thickness of a cylinder head so I can tell how much has been shaved off this one? even if I toss this one, I would like to know so I can verify a used replacement as good.

Also do I really nee the shim if this head has had 0.7 mm shaved off it? I know the compression will be higher but will the valve hit the pistons? will the valve timing be radically affected? andwill it ping badly?

Cheers, Lutz

hi , don't know about the thickness of the head but when i got my ed head recod i asked the machinist to shave the head . he said any more than 30thou i'll need to run shim plate on it .

Thanks Philbie

Yes, I think I might need a new head, one that is pretty original or not much shaved off hence a desire to know the measurements!

Anyone?

Normally on alloy heads you will see on the edge of the casting a small area that is slightly lower than the surface that you machine. This is normally considered the limit that the head can be milled to. I doubt you will see this on your cly head, but if you look at a head that has minimal machine work done on it you will see what i mean. Hope this helps

I had this once on an XF reco engine.....I left the shim out...went good, no pinging either.

Thanks Mick, I think i know what you mean with regards to a little bit of unmachined area. mine is certainly flush at best. So its at least at the machining limit?

I am very tempted just to through it together with the old shim? maybe i should get a new shim?

Lutz

Hi CJ,

I am thinking about leaving it out or just reusing it. I guess a ef might be totally more fussy than an xf on compression or maybe the valves hit the piston easier?

Cheers,

Lutz

bump????

yes, shims are available for the OHC's in 0.8 and 1.5mm, they are sometimes used when the head has been machined a fair amount, to stop valves hitting pistons and also to stop timing chain noise as the tensioners cannot take up all the slack.

Last edited by 66 coupe on Sun Jan 02, 2011 4:28 pm, edited 1 time in total.

OHC? where can I find them?

i have them available, follow link in my profile