First time installing a head on a 1275

[cdsmith]

Well.. Sick of me yet?

The head is back from the machine shop, so I get to re-install the head - I've never done this before!

So I'm looking for some answers to what might be some dumb questions... (Note: it is a 1275 that is being worked on)

1st:
Valve train is held on by 4 head nuts and 4 smaller nuts, so should the torque setting be the same for all of them? If not, what should the torque setting be for the smaller nuts?

2nd:
I have been told to re-torque the head nuts after running it up to temp, and letting it cool down (and also do this again after about 500 miles). Now I have 2 questions; First question is when I re-torque the head nuts do I also re-torque the smaller nuts holding the valve train? Second question is when I re-torque the head do I back off the nuts 1/4 turn (1 flat) before I re-torque?

3rd:
Anything else??? Remember I've not done this before...
As always... Thanks a bunch!
CD

 

[spritenut]

The smaller nuts on the rocker shaft should be torqued to 22 ft lbs. In sequence middle first and work outward 2-3-1-4 or 3-2-4-1.
I have never re-torqued when it first warmed up, but always after the first 500 miles. Head and rocker nuts. And readjust the valves after a retorque. I never backed the nuts off either and I have popped off and replaced 1275 heads probably 100 times.

 

[dklawson]

100 head changes! You are a busy guy! Regardless, I have never done an immediate retorque either. I wait about 500 miles. However, I do back the nuts off 1/4 turn then tighten them again (one at a time... I don't loosen all of them at once).

There are some who say that if you are using the shiny, varnish coated Payen gaskets you should put the head on and start the engine up "dry", no coolant, and run the engine until the head just starts to get warm to the touch. This is followed by a "cool down" during which you are supposed to retorque the head. Finally when it's completely cool you're supposed to fill the cooling system. Mind you, I've never tried it. Supposedly it gets the varnish on the gasket to make a very good seal with the head and block. I never could bring myself to try it.

 

[SANdMAN_the]

definately do NOT torque the smaller nuts to the same torque as the larger ones. i made that mistake and broke the two studs. on the bright side, it gave me an excuse to buy a drill press, screw extractors and a tap/die set (great for cleaning out threads when things don't go in by hand).

john.

 

[cdsmith]

Well...

I finally got some free time to re-install the head (also had to re-install the gas tank - had it cleaned out and lined, repositioning the fuel pump - near the gas tank, and there were a few other misc things that needed to be done...)

The install went okay, but... there is always a "but"

After I torqued the head and adjusted the valves I ran it up to temp and let it cool down. The next day I had a coolant leak at the head gasket (on the side under the intake and exhaust manifolds). It is a nice little bit of seepage -- and it is definitely seeping at the head gasket. So I re-torque the head, adjusted the valves, and ran it up to temp again let it cool down -- still got a leak!

I'm thinking (hoping) the head gasket was faulty (it was a Beck/Arnley part), but could be something else (warped block?). I didn't have any leaks before the head was pulled, so I don’t really suspect the block. I'm assuming the head it nice and flat -- it should be given the valve job.

Any suggestions? I would like to do everything possible before I go the way of a new head gasket...

Once again thanks for any ideas…
CD

 

[spritenut]

It is a good idea to countersink the head studs where they meet the block. Don't drill them thru, just take a wee bit off the block.
The head studs do pull up the metal around them when torqued down. They may be raised just enough to cause a leak.
Also, some head gaskets are marked top/front, is it on correctly?
Any old gasket still stuck to the block or head?
And bum gaskets out of the box are not unheard of.

Frank

 

[dklawson]

In addition to the advice above on c-sinking the stud holes in the block, get yourself a better head gasket and have the head (and block) checked for flatness. Just because you took the head in for a valve job does NOT mean that the shop will have checked or machined it flat. This applies to the block as well. Obviously if the head isn't flat you'll need it resurfaced before installing it again.
As for the head gasket, consider the black Payen gasket. I order my parts from Mini Spares (same head gasket) but I'm sure other people in the U.S. will have the gasket.