possible cylinder head issue

[BENCLARK]

Hi Z Fans

i've rebuilt the engine but have got my tits in a twist over cam cap bolt torques!!!

had to helicoil 2 stripped threads even though they appeared to be ok on disassembly.

I have searched cam cap bolt torques on here and found a wealth of do's and dont's.

really concerned that i have not got anywhere near the 17NM torque setting the good service schedule stipulates.

Any advice on cam cap bolt torques would be much appreciated.

As a aircraft technician by trade it goes against the grain to fire up the engine knowing things aren't 100%.

[z1bman]

12nm is enough or just nip them up. anything more with using old bolts & worn threads & you will be cursing

[zed1015]

17nm is 12.5 ft/lbs and is too much no matter what the book says.
8 to 10 ft/lbs or the equivalent is the maximum, especially given the age of the alloy.
I never use a torque wrench on these and just nip them by hand with a 10 mm spanner.

[BENCLARK]

Z1bman, Zed1015

Thanks for the advice. After 3 attempts managed to get 7NM torque down on all the cam caps with the motor spinning freely by hand at the crank using 17mm ring spanner.

[weaver]

I've always used 7nm with no problems

[BENCLARK]

I've always used 7nm with no problems

Great to hear!! Thanks Weaver.

Tightened them up in sequence and 7NM was achieved.

These old jap fours are so much more rewarding than the modern stuff even if they test us on occasion.

[kev edwards]

17nm is 12.5 ft/lbs and is too much no matter what the book says.
8 to 10 ft/lbs or the equivalent is the maximum, especially given the age of the alloy.
I never use a torque wrench on these and just nip them by hand with a 10 mm spanner.

I do them the same way, and absolutely do not do them up to torque values if they are chrome plated as you will strip the threads in the head or cases.