Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Retorquing Head Bolts question

I I have some oil oozing from the head gasket at the left, rear of my TR4 powered +4 (very slight amount) and thought I would try retorquing the head bolts before going whole hog and replacing the copper gasket.

However, when I removed the valve cover, I realized that I couldn't get access with a socket and torque wrench to the upper row of head nuts (the ones that live amongst the valves under the valve cover) due to obstruction by the valve springs.

Do you use "crow's foot" wrenches to retorque? Do the valve springs need to be removed to retorque the head?

Any advice appreciated.

Cheers.

GC

I use a crowsfoot socket.

No need to remove valve springs but you can take the rocker shaft off as you may as well reset the valve clearances whilst you are at it!

Arwyn

I had a TR4 A back in the day and the head gaskets were always leaking! I don't remember the option of crowsfoot heads in those days although I think I might have tried a small tweek If I had some then. I just loosened the tappets and lifted of the valve train, doesn't take long. A little tighten can reduce the leak but it didn't last in my experience. Once I tried to tighten a corner down and found that the head bolt had failed, couldn't have got to more than 20Lb foot and it sheared like cheese. As far as I remember they are stretch bolts and you can use them twice but Triumph recommended new. I'm also fairly sure they brought an improved head gasket out some tome in the early to mid 70's which should help solve those weak areas.

Thank you Arwyn - thought a crowsfoot socket would work - just wasn't sure if the torque values would be the same. consensus seems to be that 90 ft/lbs is sufficient for a retorque.

Now the big question - which I'm sure will elicit a lot of opinion...

Retorque hot or cold? Back off bolts first?

Was going to back off 1 flat cold and retorque cold - but I've read other opinions...

I would retorque cold and not back them off. The idea being that you maintain a clamping force on both the head gasket and the figure 8 gaskets at the bottom of the cylinder liners

Just check your torque values- seem remember the given figure being about 105 ft lb - but would need to check.

Make sure you have the correct washers under the nuts.

Don't think the cylinder head studs are stretch bolts but they are cheap enough to replace as to matter of course in a build and if you were going for serious power you would use ARP hardware

Arwyn

I read (but haven't checked) that a torque wrench will read right with a crows-foot as long as it's 'dead ahead' but won't be accurate if it's skewed to one side ... you'd need a torque wrench calibrating rig to check that out ... always mean to see if my mate with the engineering firm has one and do the experiment but never got round to it.

K

So apparently there's a formula to account for the increased torque when using a crowfoot socket:

https://www.tekton.com/blog/how-to-accurately-use-a-torque-wrench-with-a-crowfoot-wrench

If the crowfoot is at 90 degrees to the wrench no adjustment needed...if it's not 90 degrees, wrench needs to be set to a few ft/lbs LESS...

Manual says torque on head studs should be 105....but GoMOG says 90...will probably split the difference and call it a day!

As always Arwyn - thanks for the advice...

A crows foot extension will work with a torque wrench accurately only if the wrench is at 90° to the offset of the crows foot. This because the bolt/nut and torque wrench centres then lie in the same plane. Worst case however is if the crows foot extension is in line with the torque wrench arm, increasing the leverage accordingly and so causing over torqueing to that of the wrench setting. Anything in between will also be wrong to some degree.

Edit: posts crossed but we seem to be in agreement, although I wouldn't argue with a crowbar

Knew I'd remembered something but had it crossed ... good to get chapter and verse! 👍

K