Jump to content

Re- torqueing cylinder head


Recommended Posts

It proves little, but my show car with ~4000 miles since its engine was apart is bone dry at the head/block interface. I checked the tightness after 130 miles but nothing moved ( 75 lb-ft ) and haven't done so since. I was thinking to remove the rocker shaft and put the torque wrench to it now ( never thought of loosening first :unsure: ) but now I'm on the fence.

 

My driver's engine's been weeping oil at the interface as long as I can remember - last time it was apart was nearly 80K miles and 14 years ago. I'm sure I retorqued that one ;) .

 

I too wonder why turning a stud would cause a leak ( and why a stud would want to turn after initial torqueing anyway ) :huh: .

 

Cheers,

Tom

Link to post
Share on other sites

Tom, I'd figure if anyone on here could talk intelligently about torque, it'd be you!

 

My dad once told a good customer " Make sure you screw it up right! "

 

That's about the extent of what I know - though I guess why some would think I should be an expert ( www.torque-inc.com ) ^_^ . Here's a tidbit then: the aggregate clamping force of the head nuts ( 14 @ 80 lb-ft ) is 150,000 lbs, or 75 tons.

 

Cheers,

Tom

Link to post
Share on other sites

Name them on this topic?

Alec,

 

In answer to your question in my opinion it does. Coopers designed, developed and manufactured this head gasket along with all other B.L. Head Gaskets. Coopers as a company are long gone of course. The original head gasket base core was a laminate of CAF + Tinplate + CAF. The use of CAF materials have been prohibited for over 25 years. One of the main properties of CAF was that it was very good at holding its torque load under heat, pressure and not degraded by oil. Substitute materials will now have to be used and often these material(s) do not have exactly the same properties as the original. Therefore, I believe that re-torqueing is required to check the loading on the head gasket after a certain number of miles.

 

Bruce.

Link to post
Share on other sites

Neil,

 

I see where you are coming from!

 

Payen was the after market division of Coopers, bought by Felpro! Just say that I am a sceptic and I would be surprised if Felpro (Payen) would apply their latest technology to a 40 + year old design Head Gasket but I could be wrong!

 

Bruce.

Link to post
Share on other sites

Neil,

 

I see where you are coming from!

 

Payen was the after market division of Coopers, bought by Felpro! Just say that I am a sceptic and I would be surprised if Felpro (Payen) would apply their latest technology to a 40 + year old design Head Gasket but I could be wrong!

 

Bruce.

Thank you Bruce ;) you get what you pay for :)

Link to post
Share on other sites

Interesting to read the various suggestions for achieving a good head gasket seal.

In my opinion, for what it's worth, the important factors are the flatness and cleanliness of the 2 mating surfaces. The new/old stud argument is, l believe, of secondary importance due to the link between actual torque applied and the resultant clamping force.

 

My exPI saloon engine, fitted to a TR250 (with MG XXX engine number and recessed bores), has had no sealing issues or oil staining at block number stamp after 10k miles and 3 years of use.

 

Initially torqued to 80 ft lb, then re-torqued at 500 miles.

Before retorquing I mark the '12 o'clock' position on each nut with a small dab of white correction fluid.

Using the recommended sequence, the first nut is slackened by about 60 degrees , then 80 ft lbs reapplied. Generally all nuts tighten approximately 30 degrees beyond their 12 o'clock initial position.

 

Of course every engine is different, but the above worked for me.

 

Jerry West

Link to post
Share on other sites

Guess that agrees with post #3 then.

 

Mick Richards

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.