Advice on oil leak at head bolt

[T. Cotten]

... A large fine machinists file for the deck and glass on a flat work bench will be plenty adequate for a stock (compression) engine. ...

You left out hours of careful observation and patience, Peter!

And also to chalk the file, especially if it is "fine" rather than a bastard, particularly for aluminum.

Got a good way to hold the head so you can use both hands on the file?

Don't get me wrong, I always roughed-out pulled Pan headbolt inserts with files, before they were finish-ground.

...Cotten
PS: I often used 1/4" tempered cabinet glass, but even it will still "move" if it is not supported on an equally flat surface, risking 'rounding' the surface at the edges. Glass is liquid.

PPS:

.. How do you measure flatness on the cylinder deck accurately? ...

My first inspection, Lipdog,..
Is swiping it across my large stones, and reading the profile. You might try large adhesive discs upon fat flat glass.
If it grinds "clean" you're doin' good. Your progress can be tracked with another glass plate, and feeler gauges. You could even "ink" it if you are anal like I was.

[Lipdog]

That 50 ft lbs taking into account bolt shank diameter and distance from washer flat underside to thread engagement in the deck means this spec focuses entirely on crushing those inferior gaskets into submission to avoid failure at focused hot spots (exhaust) with no consideration for thermal expansion of the metal components. No 70-80 year old heads asked to operated under this duress can do this forever. Fours notoriously begin to crush at the washer lands and though functionally repairable at great expense, visually are ruined as the cooling fins become warped. Vincent’s (without head gaskets, no less) and air air cooled Porsche’s (making 150bhp/Litre on turbos) run no more that 30 ft lbs. 25 ago, after wrenching on a 441 midway across a US tour with its heads ruined,I came home did the above on my 440 and torqued to 30 ft lbs, many miles later, no carbon tracking. On my stock 346 it’s 40 ft lbs and the hot rod 348 at a little over 40. Your results may vary.

I generally buy your argument and may torque the head bolts less when I do this job (maybe try 40-45 ft-lbs). There isn't much downside, as these head gaskets look fairly straightforward to do. But the one other reason to torque to a higher value is to ensure enough tension/stretch in the bolts, which ensures they maintain clamping force. The last head work I did was for my Ford FE (all aluminum Robert Pond block and heads). Those are 1/2" bolts that require 85 ft-lbs. Of course, they have to separate oil, coolant, and fuel air, under far higher compression and power, but that is a lot more torque.

[T. Cotten]

Fifty-five has been a consensus, Lipdog!

(For Chiefs, that is... Coincidentally for most Brand X flatties as well.)

And with a modern gasket, re-torques were just to feel good.

Yer on your own with copper.

...Cotten

[Tom Wilcock]

An old rider/mechanic once told me to soak the fiber gaskets in water for a period of time and then install and torque them. They never need retorquing and never leak. It always worked for him.
Tom

[Lipdog]

Hey Gents. I'm getting around to planning this job. One additional question: how do I know this is unburnt combustion/oil byproducts, and not oil getting past the rings or guides? Is it possible to do a leak down test to get a better idea? Thanks again.
Jeff

[Lipdog]

Update: i did a leak down test and got a reading of 10-12% at the front cylinder, and 8-10% at the rear. Though I did it at a relatively low pressure of 50 pounds. No detectable leakage at the valves, only at the rings. I think those results are pretty impressive for such an old design, and lead me to believe you are correct and it is just the head gaskets.