Re- torqing Head

[Ginger Bear]

If your head & block have been skimmed & you're using standard head nuts, it's worth checking. APE head nuts are made extra tall/deep to overcome this.

Also if the head or block have been skimmed, check the length of the two outside locating dowels, they may need shortening too......

[hanskloss]

GB got me worried with the dowels, but than I remembered checking head on block with no gasket and that went fully on so OK, the head has beed skimmed 0.1mm just to clear old gasket marks, block was just cleaned, might undo one head cap nut next time just to double check

[Ginger Bear]

Hankloss, 0.1mm will be fine I'm sure. My head & barrels had both been skimmed & poss before by a previous owner.

Had a serious oil leak from the side of the head where the over length dowels stopped the oilways sealing.

[jimmock]

Build engine, Torque head.

Run engine nice and hot . Leave to cool overnight, Re-torque cold next day.

Re-torque in proper sequence after 500 miles ( no mucking about slackening the nuts , just re-torque)

Has worked for me for 40 years. Job done.

Zed1015,

Your system is obviously for a guy who works days.

What if it was a nightshift worker????

[zed1015]

He should run the engine before he goes to work and then re-torque the head when he gets home before he goes to bed.

[LTD Project]

I hate to put the cat amongst the pigeons on this one but.....

We were always taught at Rolls Royce that where torque settings were important, the thread should be clean and dry.

Not lubed as previously mentioned. The lube enables the over-tightening against a specific torque.

There is a mind numbing article somewhere that explains this in more detail. If anyone is that interested I will try to dig it out, please dont ask....

That said I am the first to lube a thread where I know it may be a sod to undo due to rust/dirt/corrosion.

but there are some that should be clean and dry.

I await the onslaught....

[zed1015]

I have a few regular motocross guys for whom i build and maintain their race engines.

The YZF450 four stroke head torque sequence goes like this.

1. Wash the four cylinder bolts, dry off and coat the threads and both sides of the washers with moly grease.

2. Torque in sequence to 22lb.

3. Remove all studs ,wash off the grease, dry off then re- moly grease threads and both sides of washers.

4.re-fit and re-torque to 14lb.

5. Then mark the bolt head and corresponding point on the head and then in stages angle torque till the mark on the bolt head is orientated 180 Deg from the mark on the head.

How the heck they come up with this i don't know but it's a pain in the ar*e repeating it every few weeks.

[LTD Project]

I should imagine that the specified torque settings have the moly grease taken into account..

but would say that where no lubrication is specified, then there should be none so as to attain the correct torque-ing as envisaged when the engineer specified that particular size and pitch of thread

I am not too precious about it myself as I mentioned earlier, just thought that it may be a point of interest for those that may care.

I know for certain that there are very many more experienced and highly competent spanner turners on this site than me and I would bow to their knowledge everytime.