Torquing/Retorquing cylinder head

[Michael Oritt]

I just reinstalled the cylinder head in the Elva after having it very lightly skimmed, springs renewed, valves and seats reground, etc. I used a Payen composition gasket and torqued it gradually up to 50 ft/lbs in the normal manner, then ran it and all seems good.

I would appreciate input and experience on if, when and how to retorque and specifically on

1. Whether it is advisable--or not--to back off head nuts to where they turn just slightly and then retighten in succession

2. Whether it is advisable to drain coolant down below deck level while doing this.

3. Whether or not engine should be hot or cold.

 

[dougie]

Michael - A couple questions: Aluminum or iron head, ARP studs, gaskets sealer, type and amount?

Dougie

 

[pjsmetana]

Granted I have not rebuilt a British engine yet, but I cant see how much of this would make a difference, so in my engine building experience and no matter what the answers to Dougie are;

1. Do not back off. Just retorque. Backing off can, and most likely will weaken your head gasket.
2. Definitely drain coolant below deck levels.
3. Cold. Metal expands under heat, it was installed cold, and the torque values are for cold. Doing it while hot can result in a cracked head or over stretched studs later.

 

[Michael Oritt]

Dougie--

Iron head
ARP studs
No gasket sealer

 

[aeronca65t]

This may be one of those questions like:
<span style="font-style: italic">"What's better? DOT3 brake fluid or silicone?"</span>

Anyway, here's my answer/opinion (for iron head, pushrod).


~Assuming clean, oiled threads, do not back off.
~Loosen radiator cap (to reduce any residual pressure) but no need to drain fluid.
~Torque head with engine cold.
~Work a sequence/pattern from "center out" of head when tightening.
~I usually do this after several hours of running (I don't wait for 500 miles which used to be a pretty common recommendation).

Technically, you shouldn't really need to do a re-torque with most modern head gaskets.
But I've been know to wear belts and suspenders myself.

 

[dougie]

Dougie--

Iron head
ARP studs
No gasket sealer

Michael -

With an iron head I always re-torque when warm, aluminum cold. I relieve pressure in the coolant system like Niels and don't drain. I do back each nut off 1/4 turn following the tech manuals sequence then re-torque to ARP specs. This has always worked for me with no future leaks. I usually break things in about 300 mile first though. BTW I have had great luck with Joe Gibbs break-in oil and his Hot Rod oil for winter storage.

 

[pjsmetana]

... I do back each nut off 1/4 turn following the tech manuals sequence then re-torque to ARP specs...

Not to start an argument or anything, and I know every builder has his/her own techniques, but... Aren't those bolts designed to stretch only once? I mean, that is why we never reuse bolts isn't it?

 

[martx-5]

I have ARP studs on my TR3, and when confronted with re-torqueing the head I called up the ARP tech line. He said to back off the nuts one at a time and re-torque to specs. I followed ARP's recommendation which may not be the same for your application of stud/bolt type.

Edit: ARP also said to re-torque after an hour or so of running.