Best fix for damaged nipple?

[Jack K]

If it was yours, how would you fix it?

Not sure but I think the damage was done by the very narrow OEM O-ring clamp slipping toward the carburetor flange and becoming cocked over on the inside. This scar was on this nipple when I acquired this head over 35 years ago and has sealed fine until now. What has changed is the head along with the front head have been re-surfaced. Also the available replacement O-rings don't seem to be as pliable as they should be.

Any help and/or advise appreciated.

[T. Cotten]

Jack!

You will find JAMES viton O-rings to be compliant, and far, far more resistant to modern fuels.
The scar does not seem extreme to me; Be certain that your replacement clamps, however, use only a #10 screw fastener like the OEM design, as over-tightening may cause problems.
(Beware also that some modern aftermarket stainless clamps are over .750" wide, and often need to be ground to fit.)

Of graver concern may be the stress crack from the headbolt insert, which may extend into the region I have indicated in the attachment.
Please use a #9 rubber stopper with a nipple through it to apply a constant, regulated 12-15psi of airpressure so that soapy water will display any breach to the port. The seam around the headbolt insert should be inspected as well.
It it proves sound, the stopper can them be used upon the mouth of the installed manifold to assure that the clamps and O-rings are secure.

Good Luck!

....Cotten

[Jack K]

Good eye Cotton.

There is a big difference in "looking" and "seeing". I've been looking very hard for the source of the leak but I just didn't see it. Should have known it wasn't the nipple, after all, 35+ years and its never leaked. Thanks.

Cracks are often difficult to spot in aluminium but I believe the crack running from outside under the nipple to the insert exits inside the intake chamber where a ton of aluminium has been removed down to the steel insert. It doesn't look as though the crack running over the fire ring recess goes as far as the insert. Maybe its not a crack at all. Please take a look at the attachments. What do you think?SD531440_0219.jpgSD531441_0220.jpgSD531442_0221.jpgSD531443_0222.jpg

[Jack K]

Cotton,

The O rings are James and they just feel more like plastic than rubber,,, probably not a problem thou.SD531446_0225.jpg

And I'm using OEM clamps.SD531448_0227.jpg

Also, I use an array of fixtures to check for leaks,,, they are way cheaper than pistons, valves, etc.SD531445_0224.jpgSD531423_0208.jpg

It's really great to have this forum. I had become so frustrated with what I had anticipated would be a simple, pleasurable little job that I could NOT find a leak that now looks so obvious. Again, thanks.

[T. Cotten]

Jack!

With over 2MB of attachments, my dial-up can no longer handle it without timing out repeatedly (at 2 cents a minute.) No matter what I would see, its all about the bubbles anyway.

And beware JAMES offers common O-rings too, of course. P4gas swells them like balloons. Viton is a purplish red color, and barely swells detectably.
I cannot view your apparatus, but I hope it includes a #9 stopper!

...Cotten

[T. Cotten]

Jack!

After letting my dial-up connection cook for some time, I could enlarge the thumbnails, however they were over-exposed and "psychedelic". Graciously, I could then save them to my photoeditor and view them in detail.

The photo with the dental mirror raises a question or two:
Is there a pressed-in seat insert installed on top of the layer of cast-in bronze seat?
It would be prudent to attempt to bubbletest the chamber, around the seat area. Even cast-in seats have been known to leak.
Again, a rubber stopper in place of the valve could be used, with a long bolt through the valve guide to secure it.

Please note the inherent porosity of the head casting. "Cheesiness" may exist with the core of the casting, and the stress crack connect it to the port in a diabolical manner.
Another evil aspect is that it might only breach while under 65 ft-lbs of torque!
I do not believe the headbolt insert is a concern in itself, but no possible path for leakage should be overlooked.

What year is the casting?
Can we assume those are FLH ports?

....Cotten
PS: I would have edited and added this to my previous post, but the site's format will not allow my Opera to do so. Neither can I use the drag-and drop function to add any of my previous attachments.
Ironically, I can drive to my shop and use a much older IE browser, and edits work, but my log of previous photos is un-accessible.