Head Intake Threads and Seals ... Head Hog?

[40 Nuck]

I have a couple of OEM heads that have been altered for O-Ring Intake and would like to go back to threaded so that I can mount the original brass intake and linkert. Any suggestions on whether this would be recommended, and if so, a good vendor. I've run across Head Hog (Don Sullivan), and wondering about feedback on them as a vendor. Also like their valve seat solution ... and was wondering if anyone had feedback on that. Also, I've noticed the articles in the AMCA mag on the new intake manifold seals that suggest that they eliminate the plumber intake seal problem, even on the brass 1940 intakes (mine is a 1940). Anyone had experience with those?

Thanks!

[chibobber]

Vic,American Cycle Fabrication,Paul can fix you up.The stock brass seals work fine if done right. Some like the synthetic seals some don't. (ACF 570-752-8715 PA)
Good luck,Bob

[Robert Luland]

I got no complaints against Don. He does great work and has always done right by me. I have read some to indifference but he’s always done good by me. His valve overlay process is incredible. He’s done four heads for me. The Peek ferule is the way to go. They cinch up at half the tork and this save putting a beating on the rivets. Bob L

[Jerry Wieland]

Vic Brass intake manifolds are not 1940. 1940 uses a short steel manifold that has the number 428-40 on it. I believe that brass intakes are 1947.

Jerry

[MJW]

I had Don re-thread my 51 pan heads, most of the original threads were gone so he welded them up and cut new ones. The only disappointment was my own error, I thought they would be air tight when I got them back with the new inserts already installed, turned out I needed to pull the intake and remove the inserts again. The skinny gasket that presses against the head had torn so I made new ones out of some gasket material, I know "goobers" are frowned upon, but I couldn't resist adding a dab of steam fitting sealer to the threads. I also made a special wrench to span the three holes in the perimeter of the inserts for tightening. No leaks yet after two years...Mike

[Chris Haynes]

Vic Brass intake manifolds are not 1940. 1940 uses a short steel manifold that has the number 428-40 on it. I believe that brass intakes are 1947.

Jerry

Jerry,
Here is a 1947. Notice the Parkerized intake? Brass doesn't Parkerize.

[40 Nuck]

1940 was the first year for the large ports (1.5") and manifold. The brass was a one-year only (1940) part as it was found that the brass on brass (bushing on manifold) resulted in leaks, but apparently the brass manifold lasted most, if not all of the model year until it could be replaced. Thanks all for the feedback on vendors ... sounds like I have some solid options, and that there is hope for my O-ring heads.

[koanes]

Chris, That prototype picture may have an iron manifold, but every original 47 knuck I have seen has a brass manifold. I always sneek a peek at the top of the manifold where the choke rod rubs, (they all do) and you can clearly see brass. Vic, the Peek seals are the way to go, far less torque on the nuts to get a good seal. I've never heard anyone speak poorly of them. Many thanks to Tom C. for bringing that material to my attention.

[T. Cotten]

All bronze OHV manifolds that I have re-conditioned were long, not short like the '40.
They most often were found upon '47 EL's, and they are also prone to horrendous casting porosities, as shown in the attachments.

Moldthread's cast PEEK seals are ideal, if your manifold spigots are pristine and of the original diameter.
Bronze manifolds are more malleable than even steel, and have nearly all worn or distorted with use. Therefore, they require swaging before re-cutting to accept a fresh seal of any material.
PEEK seals have proven user-friendly and reliable when properly re-torqued, and in the decade of their use, nobody has worn any out. They are re-useable as long as the spigots were pristine in the first place. Blemished surfaces will make impressions that can be sanded out for re-use, but naturally shorten the seals' otherwise infinite lifetime.

The bottom line with any manifold seal is to properly test it before risking the motor.
This only requires air pressure, soapy water, and a little patience: http://virtualindian.org/11techleaktest.html

Beware that barnyard tests give barnyard results; The porosities shown below could not be detected by spraying it while the motor was running.

The greatest obstacle to restoring intakes is finding a sealer for the nipple thread that not only resists today's digestive fuels, but tomorrow's.

.....Cotten

[Jerry Wieland]

Vic Here are pictures of knucklehead OHV intake manifolds and most of this you already know - from left, 1936 to 1939, 1940 only, 1941 to 46/maybe 47 and then the brass one.

My first knucklehead 30 years ago was a 1940. The second from the left (1940 only) has a casting number of 428-40 (all the rest have 428-401) and has the same distance from flange to port center as does the 1936 to 39. If you do not believe this is 40 only then try fitting your 7" air cleaner on a bike with this manifold - just make sure you have your hammer handy cuz you're gonna have to bend something. The 6" air cleaner that came stock on a 1940 has clearance but the 7" in 1941 necessiated lengthening of the throat of the manifold.

Don't quote Palmer on this one - he's been educated now but when he wrote his book both he and Chris were should we say - uninformed on this matter.





Chris next time you get around an original 47 look real close at the intake like Kyle said. Brass almost always shows thru by the choke rod.

Jerry