head bolt torque and block

[Ruairidh Dunford]

My experience of modern head gaskets is the same, they continue to compress, resulting tightening is very different from old.

[Hedd_Jones]

I've got some fixings to do up tomorrow, some 5/8 some 3/4 and a couple of 7/8 whit. They are all original pre was fixings that have been inspected and re used as in good condition. 

Looking up what I might wang them up to if they were of known material makes very intersting reading. If I knew they were equivalent to modern 8.8, The recommended torque is more than double if they were equivalent to modern 4.6. 

Now, I have plenty of torque wrenches, but none with sufficient capacity for tomorrows job. No room for leverage either so tomorrow will likely involve use of my leg muscles and or ring spanner wrapped around an open ender, and might involve some spanner bendingto get them 'FT'. 

My advice is that if youve been through your engine (or whatever) inspected (and repaired) every thread, replaced the fixings with known products and or materials, then crack on with your torque wrench. 

If you havn't been through the fixings as above, wanging things well up with your torque wrench and your dicing with death. You will break things, and it will cause you a load of aggro. Drilling out head studs is not a nice job, not that you can get a torque wrench on a block stud, but break or pull one of them and it will lead to an engine rebuild. Drilling a manifold stud in situ is a real game. So engine out job. 

There is always the danger that asking such questions is that someone always brings up a reference which is always perhaps a little more than the more considered and tested norm. The danger is particularly with untrained amateur mechanics (or engineers) that more is better. And it really isn't quite often. 

The reality is the the Austin 7 engine in its simplest unmolested form fitted to a standard car is pretty unstressed. You do not need the head studs torqued to the point where something is about to go plastic to keep the head on or ensure its water tight. 

The other point worth noting is that in my experience the majority of cylinder blocks are cracked at the centre stud. So your fixing is suspect to start with. Yet the blocks generally remain perfectly servicable in normal use. 

I have 4 running engines here. 1 by Vince Leek. 3 by unknown long time ago. I'd happily use a torque wrench on Vinces head studs (not that Ive ever had the head off). There is not a chance I'd use one on the other three.

[JoeRowing]

interesting - I rather thought the danger of not using a torque wrench on the head and manifold nuts is overtightening...

[Steve kay]

Very much my thoughts, we are told to use the torque wrench to make sure that accuracy avoids over tightening.

[Ivor Hawkins]

I too have four torque wrenches, I even use the 1/4” drive version to tighten the head accurately on my banjos!

However, I used the 3/8” drive version when tightening the head down before Moreton and at 30 ft ills, one of the nuts “went soft” so I imagine I have stripped a stud or a nut...I’ve left it until next time I whip the head off and I’ll go for 25 ft lbs next time.

[Charles P]

It's always worth testing the calibration of torque wrenches from time to time. Two 5 litre water containers gives a handy 10kg load to hang on a string at a suitable distance and setting to see if it clicks.
One advantage of the cheap and cheerful "bendy beam" type is that they can't really go out of calibration

Charles

[JoeRowing]

It's always worth testing the calibration of torque wrenches from time to time. Two 5 litre water containers gives a handy 10kg load to hang on a string at a suitable distance and setting to see if it clicks.
One advantage of the cheap and cheerful "bendy beam" type is that they can't really go out of calibration

Charles

I have a newton meter (also calibrated) and a torque arm handy for calibrating from my bicycle building...

[Charles P]

It's always worth testing the calibration of torque wrenches from time to time. Two 5 litre water containers gives a handy 10kg load to hang on a string at a suitable distance and setting to see if it clicks.
One advantage of the cheap and cheerful "bendy beam" type is that they can't really go out of calibration

Charles

I have a newton meter (also calibrated) and a torque arm handy for calibrating from my bicycle building...

I have a torque arm to I use on the block studs which I have through bolted.