O-ring intake imperfections

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kevsett
Posts: 278
Joined: Mon Jan 31, 2005 6:45 pm
Bikes: 1964 FL
Location: Missouri

O-ring intake imperfections

#1

Post by kevsett » Wed Oct 26, 2005 10:26 pm

I just purchased an unused intake (not NOS) and on the inside bottom of the feed throat passage is an imperfection, kind of like a small chunk hole. Without a visual I'm sure my description makes no sense so I'll try to take a pic or two and post.
There are also casting imperfections all along the inside middle of the intake from where the two piece mold was.
So my question is whether these imperfections are a problem for fuel and air to pass along as they head to the intake valves? I've always thought that an intake should be somewhat smooth but several mechanics here where I work seem to think the need for a smooth, polished intake is of little concern.
All I know is that the just purchased intake interior surfaces appear sloppy and downright porous when compared to the stock intake; which still requires a flat grind on the mounting flange surface if I decide to go back with it.

Here are some pictures of the "pothole" in the right side of the intake chamber.
intake1.jpg
intake2.jpg
intake3.jpg
intake4.jpg
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caschnd1
Posts: 606
Joined: Tue Apr 25, 2006 3:45 pm
Bikes: 1949 FL Chopper

Re: O-ring intake imperfections

#2

Post by caschnd1 » Thu Oct 27, 2005 2:42 pm

That is some pretty sloppy casting work. I've always tried to get my manifold nice and smooth on the inside. You might be able to achieve the same result by filling the imperfections with epoxy. The only thing I'd be concerned about is if the epoxy decides to let go it going right into your motor. May not be worth trying to fix.

-Craig

fourthgear
Posts: 1390
Joined: Mon Apr 11, 2005 1:12 pm
Location: north florida

Re: O-ring intake imperfections

#3

Post by fourthgear » Thu Oct 27, 2005 3:08 pm

I was told a long time ago that it was best to have them a little rough to create turbulence to atomize the fuel better or something to that effect. although some make them like mirrors, Thats a good pit in there !

Rainjester
Posts: 67
Joined: Fri Jan 07, 2005 7:23 pm

Re: O-ring intake imperfections

#4

Post by Rainjester » Thu Oct 27, 2005 9:02 pm

Nothing a little JB weld won't fix but hey, if it were me and my bike, I'd throw it away and find a better one. A nice replacement doesn't cost that much. That one looks a bit too funky to me.

jester-

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: O-ring intake imperfections

#5

Post by Cotten » Fri Oct 28, 2005 2:52 am

Panhead intake velocities are nowhere near the cfm where such a tiny pit would be significant (nor polishing for that matter!)
Indeed, turbulance helps keep the fuel in suspension at low velocities.

It is a very real concern, however, that the porosity may breach to the outside. Please pressuretest, as many leaks can be invisible to the naked eye.

If there is no leak, I wouldn't hesitate to run it at all.
(although those knarfs on the o-ring shoulder aren't desireable!)

...Cotten

kevsett
Posts: 278
Joined: Mon Jan 31, 2005 6:45 pm
Bikes: 1964 FL
Location: Missouri

Re: O-ring intake imperfections

#6

Post by kevsett » Fri Oct 28, 2005 6:31 pm

Thanks for the responses. If I decide to use this one rather than the stock manifold I'll pressure test it by itself.

Cotton, can you elaborate on the knarfs?

Cotten
Posts: 6911
Joined: Mon Aug 26, 2002 9:09 am
Location: Central Illinois

Re: O-ring intake imperfections

#7

Post by Cotten » Sat Oct 29, 2005 2:19 am

The last pic shows two blemishes on the top half of the 'spigot'. These are typical of a careless dis-assembly.

If re-assembly proves to be sealed by pressuretesting, don't worry about it.

...Cotten

kevsett
Posts: 278
Joined: Mon Jan 31, 2005 6:45 pm
Bikes: 1964 FL
Location: Missouri

Re: O-ring intake imperfections

#8

Post by kevsett » Wed Nov 02, 2005 4:41 pm

Thanks everyone for your comments. The original intake flange and linkert flange are both being flattened (figure 8's on sandpaper taped to glass) when time allows so I'll probably keep using it and will worry about the recently acquired intake later. Oh well, it was cheap!

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