Torque setting for 254 cylinder head ?

Old Fogey UK
Old Fogey UK Expert Adviser
in HUDSON
The 34-37 Mechanical Procedure Manual doesn't give a torque setting for the head.
The post war Manual says 45 foot pounds but the Railton Manual says 55 foot pounds.
Why the difference ? Which is correct ?
I've torqued the head to 45 but have noticed a slight water seepage on the header side when the car has been standing for a while. It dries up when the engine is started.
Do I need to torque the head a bit more ? Up to 55 ?

Comments

  • Toddh
    Toddh Member
    45-50 ft lbs.  how many times have you driven, then torqued the head? I assume you gave a cast iron head.  I torque a cast iron head numerous times during the first 3 or 4 months.  Always torque a cast iron head hot.  
  • Old Fogey UK
    Old Fogey UK Expert Adviser
    The head is cast iron.
    I've only driven the car about 20 miles since torquing the head.
    I'll torque it again hot - should I take it up to 50 whilst hot ?
  • Toddh
    Toddh Member
    Can’t hurt to take it to 50.  What did you use for head gasket sealant?  
  • Geoff
    Geoff Senior Contributor
    I would be wary of exceeding 45lbs  on a 87 year-old block.   If it doesn't seal at that then an extra 5;bs is not going to do it. Best sealant is aluminium paint, sprayed on  and let dry, but not harden.   Re-torque it again when hot and see if it comes down any.   I pulled a stud out of  the block on  the H8 I have just rebuilt.   Managed to tap it to 1/2" U.N.C, and ream out the hole a smidgen. 
  • Toddh
    Toddh Member
    The best gasket sealant IMHO is Permatex Copper Spray-a-Gasket. Used it in numerous splasher heads with excellent sealing qualities.  
  • Old Fogey UK
    Old Fogey UK Expert Adviser
    Thank you both for the advice.
    We checked the head with an engineer's straight edge and used Copper Spay-a-Gasket.
    We torqued it cold and then again warm after about 15 minutes of running.
    There doesn't seem to be any oil in the water nor water in the oil and the water level in the radiator doesn't seem to have dropped much.
    I'll try retorquing with a hot engine and hope it seals up.
    Please forgive my ignorance, Geoff, but could you explain what you said about a 1/2" stud ?
  • Geoff
    Geoff Senior Contributor
    I used a 1/2' stud  in place of the 7/16" one that I pulled out when torquing the head down.  I figured this was better than using a heli-coil insert.
  • Old Fogey UK
    Old Fogey UK Expert Adviser
    Geoff said:
    I used a 1/2' stud  in place of the 7/16" one that I pulled out when torquing the head down.  I figured this was better than using a heli-coil insert.
    Thanks, I understand what you were getting at now - the danger of pulling a stud out by over-torquing the head.
    You were fortunate that the stud wasn't one very close to a water passage where installing an oversize stud would have been problematic.
    My friend who did the valve seats and honing did the 2 initial torques and I'll rely on his expertise as a lifelong professional engine rebuilder to do subsequent head tightening for me.
    I'll remind him of your warning, Geoff.
  • Old Fogey UK
    Old Fogey UK Expert Adviser
    edited July 2021
    One final comment I'd make is that I'll be wary about following the Railton Owners Club repair manual in future. It recommends 55 pounds torque - I'm really glad we didn't do it that way !
  • Toddh
    Toddh Member
    If you continue to see seepage at the head nuts, consider using Bars Leak Liquid Copper. 

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