Head re-torquing

There is normally two ways of retorquing the head bolts.
In the old days, the head nuts or bolts were torqued down to a specified torque, using a torque wrench.
On newer engines it has become more common to torque the nuts and bolts to only maybe half the desired torque, and then turn the nut or bolt a specified amount of degrees extra. Let ut say, you torque the nut to 75ft. lbs, and then you turn the nud 90 degrees after that.

In your case you have such an old engine that it is most likely the first method that applies, and then the common thing is to start up the engine after it is torqued down in several steps until fully torqued. Let it run for about 1 hour, do not stop it during this time. After one hour, you stop the engine, and go to the first nut/bolt in the torque sequence, and loosen this, loosen it 90-180 degrees, and then torque it to the specified full torque. No steps this time, just torque it fully. After that you proceed to the second nut/bolt in the sequence and do the same. So, only one bolt is loosened at a time, and fully torqued before you proceed. Do this until every bolt is torqued.

After this you need to readjust the valves, because they have now gotten too little clearance.

I have never heard about any second retorque. Just one retorque after the first and initial warm up of the engine. And, the engine should not be under load during the 1 hour warm up. Just fast idle.

This is the way I have learned to do it.

The second method, using half torque and then a specified amount of degrees is a more accurate way to do it, but then someone must have told you the right torque, and the right amount of degrees to turn the bolt.
This is not the case for older engines.

Use engine oil to lubricate the threads after you have cleaned them so the nuts/bolts does not stick while torquing them.

This is in fact the excuse for halftorquing and turn a specified angle. The friction between the hole and the bolt or the bolt and the nut increase as you turn the nut/bolt more. And the difference in the friction increase between one nut/bolt and the other. So, using a fully torque means that there will be a difference in the actual pressure on the nut/bolt from bolt to bolt around the head. That is why the engine builders have started torquing only half the torque, because so early in the torque the difference in the friction is very small. And, when you then turn the nut/bolt 90 degrees or whatever the manual says, the bolts will have the same stretch, or very close to.

Well, sorry it got a bit long. Good luck.

Best regards, Bill

And yes, the rocker shaft definitely has to come off, but with only four bolts you can get it off pretty quick.

I like the idea of running the engine from an old lawn mower tank - slick idea! The block heater idea is good too - but I don't have a block heater....

BTW, what is everyone else doing about getting the torque wrench on the bottom row of bolts adjacent to the spark plugs?

I had my Oliver 1600's engine rebuilt but I never retourqued it after running it, and that was a big mistake. Ended up blowing the gasket withing 12 hours of use on the blower. Nothing too serious, but it was putting combustion gas in the radiator and it ran a little hot.

I didn't have to pull the tank on that one as it's behind the engine. I ran it for about 30 minutes or so then took it back apart and retourqued it, and since then I've put 100 hours on it no more problems.

Donovan from Wisconsin