Intake manifold nipples

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

Intake manifold nipples

#1

Post by Rainjester » Mon May 24, 2004 7:54 am

So I find I have this big leak in the intake manifold on the rear nipple on the plumbing style set up for my 53' pan. I then disassemble it with the new 2 1/8" manifold wrench I got from zoomcycle. After I get both nipples out, I was surprised to find that the thread that goes into the cylinder heads are different on the front and back heads. I didn't see any documentation stating this in any of the manuals nor the parts ordering book.
I was expecting to see them be exactly the same. This sound right or is it possible that someone put two slightly different heads on this bike?
I'm getting ready to order a new set of nipples from V-twin and just making sure I get this right.
Additional question: Would it be more reliable if I just convert over to the O-ring style intake set up that V-twin offers?

Thanks in advance!

jester-



Billy
Posts: 781
Joined: Tue Mar 23, 2004 6:57 am

Re: Intake manifold nipples

#2

Post by Billy » Mon May 24, 2004 9:49 pm

Jester, there are date codes on HD heads that are under the Lip/ between the pushrod tubes.
According to Palmer there are 5 different sets of heads used for 1948-54 I can't find any differences in Nipple Threads. But the date codes may explain the differences.
They are read like Early frames, meaning B 8=Feb 48 & so on. This is a start anyway.

Cotten
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Location: Central Illinois

Re: Intake manifold nipples

#3

Post by Cotten » Tue May 25, 2004 2:25 am

All largeport Knucks and all Pans through '54 use the same nipple. (Maybe K's and WR's as well...)

Perhaps yours has been repaired with an oversize, either a one-off, or one from a gentleman whose card is at my shop. (I remember much less than 10%, but I do remember that I still owe him for a pair.)
Colony is the primary source for HD nipples, and that is what you will get from V-Twin. They are only slightly sloppy. You will probably have to lathe-trim the length of the inside threads.
I just attempted an installation for the third time in the same knuckle head today. And I have done many. It is NOT an easy task. This one is kicking my butt,...but the customer is an established account that I cannot refuse.
The o-ring setup is only slightly easier, in that you eliminate the riveting procedure. But they hole must still be filled, and sealing between the nipple and head surface is still the same problem.
The Colony o-ring for that interface is a sad joke. So is the mega-rivet.

My preferred sealer: Seal-Lock Fluid-Weld http://silver-seal.com/" onclick="window.open(this.href);return false; has its limitations. Large gaps must be filled with J-B Weld or an isocyanate urethane.
P4gas eats anything else.
The common reason to need an oversize is improper removal of the nipple. Un-screwing is to be avoided, as the nipple's threads are occasionally distorted by the rivet, and things get torn up on the way out.
The nipple should be cut with a small wheel like a Dremel, and then crushed. A brief outline of this procedure and testing is posted at http://virtualindian.org/11techleaktest.html" onclick="window.open(this.href);return false;

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

Re: Intake manifold nipples

#4

Post by Rainjester » Tue May 25, 2004 6:11 am

Ughs! I backed out the nipples and had a bitchin' time doing it too. Your explanations answered one question for me though. The nipple that was leaking was definitely leaking through the rear cylinder head thread (smaller diameter thread side) since it was all chewed up even before I pulled it out. It had felt loose even with the rivet on it.
The stamps are kind of hard to read, but I think it says k8 for the rear head and d8 for the front. There are other numbers which I think says 119 48 for the rear and 119 60 for the front. The threads for the cylinder side of the nipples are definitely different sizes with the rear being smaller. Hmms.... I'll bring the old nipples into the local harley shop and see if anyone there is smart enough to tell me the difference.
What is supposed to be the correct way to install these nipples?

Thanks for the help.

jester-

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

Re: Intake manifold nipples

#5

Post by Rainjester » Tue May 25, 2004 7:57 pm

Turns out that rear head with the smaller diameter intake manifold nipple thread is an older 61" head and the front head is the correct 74" head. Now I know the right part to order but I wonder if the mismatched heads affects performance or reliability? Other than the nipple leak, the bike seems to have run alright.

jester-

Billy
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Joined: Tue Mar 23, 2004 6:57 am

Re: Intake manifold nipples

#6

Post by Billy » Wed May 26, 2004 6:23 am

Interesting...

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

Re: Intake manifold nipples

#7

Post by Rainjester » Wed May 26, 2004 8:28 am

Well now.. it's getting interesting indeed. I did some more research into this and found that the 119 numbers on each head help indicate which is the front and which is the rear. Maybe some of you can confirm this by looking at the casting numbers on the bottom of your cylinder heads in between the pushrods.
For example, if your bike is a stock 54 pan, I'm guessing the rear head is going to be stamped 119-542 and the front head is 119-54. Mine is a 53 pan but my rear cylinder head is 119-482. The additional 2 indicates it is a rear cylinder head which came from a 48 panhead and my front is a 119-60 which is from a 60 panhead.
Now with the information I got from the local harley shop stating that the cylinder head is from a 61" motor can't be correct because I believe they stopped making the 61" in 1939 although Im not entirely certain of this.
I'm certainly confused as to which nipples to order so for now I've just ordered the 74" ones to determine if by chance the front one had been oversized to repair the thread.

jester-

panhead
Site Admin
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Bikes: 1954 FL
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Re: Intake manifold nipples

#8

Post by panhead » Wed May 26, 2004 9:42 am

The 61" was made until 1952.

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

Re: Intake manifold nipples

#9

Post by Rainjester » Fri Jun 04, 2004 4:29 pm

Well.. I finally got the intake manifold nipples in for the 74 OHV. Turns out that the rear head is the correct size and the front head is oversized for the nipple itself. Now I'm really in a jam because I don't know where to get the oversized intake manifold nipple. :-[
I looked at the casting again and originally thought the front said 119 60 but it actually says 119 50 so it's a front head for a 1950 panhead. If I measure the diameter of the old nipple with a vernier caliper, it measures just one notch under 3 cm.
I checked vtwin catalog and other locations but don't think I'm finding the right manifold nipple for this one. Anyone got any ideas? (short of replacing the head)

jester-

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

Re: Intake manifold nipples

#10

Post by Rainjester » Fri Jun 04, 2004 5:12 pm

I meant to say that the outside diameter of the thread for the 'oversized' intake manifold nipple that goes into the cylinder head is actually one notch over 4 1/2 cm. Oops.

jester-

52EL

Re: Intake manifold nipples

#11

Post by 52EL » Fri Jun 04, 2004 7:26 pm

it wasnt making any sense that you had a 61 front and a 74 rear cyl. if you have 74 wheels in it the stroke is different and your piston would be hitting your valves not good. at this point unless ytou are doing a restoration i would seal the nipple holes and go with the o ring style manifold and just ride the damn thing!!!!!

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

Re: Intake manifold nipples

#12

Post by Rainjester » Fri Jun 04, 2004 8:39 pm

Yea, it wasn't making any sense with the 61" and 74" cylinder head sizes. That's what I get when I go to a local HD shop. Hmphs! They are 74" cylinder heads and just as Cotten's instinct suggested, it appears to have been oversized.
As for going to an O-ring style, either way I'm still in the same position since I've got what appears to be an oversized insert on the cylinder head itself and that size needs to be installed whether it be for plumbing or for O-ring. I'll stick with the plumbing. I know I can make this work once I get a correct sized nipple installed. It's just a matter of finding one!
The new nipple that I got which fits the rear cylinder head doesn't have rivet hole in the. I guess I was expecting them to have the hole in them but perhaps one is supposed to drill the hole in it after it's installed.

jester-

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

Re: Intake manifold nipples

#13

Post by Rainjester » Fri Jun 04, 2004 9:14 pm

I just called Chuck over at PanheadCity.com and he says that I'd prolly have to have the nipple custom made. In fact, he said to throw out the plumbing style and put in an O-ring setup. Hehs.

Cotten: You stated earlier that you had a contact on a card in your shop that may have what I'm looking for. You think you might be able to locate that number?

jester-

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

Re: Intake manifold nipples

#14

Post by Cotten » Sun Jun 06, 2004 3:25 am

RainJester!

Sorry to get back into this thread so late, but I'm under a lot of demands of late.
If you have a reasonably stock machine, then your best investment would be to stay with the original design of manifold. The use of PEEK as a replacement for brass has been embraced by many independent producers worldwide (other than myself), and conversion to latemodel O-rings (and their inherit problems) would not be a benefit in the long run.
I must retrieve the info of the source of oversized nipples from the shop ( I only get online at home) but again I must point out that these are oversized so far as to require an expensive tap, and a VERY steady hand to install them squarely.
I had hoped for nipples that were only .25 mm (~.010") oversized on the internal threads. Then possibly they could be crammed in upon the original damaged head threads, and avoid alignment problems.

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

Re: Intake manifold nipples

#15

Post by Rainjester » Mon Jun 07, 2004 7:50 am

Cotten!

It's cool on the timing of your responses. Though I'd like to get the bike back up and running as soon as I can, it's not terribly urgent and I appreciate any help you can provide when you can.
I measured the O.D. of the oversized thread of the nipple for the front 1950 cylinder head in comparision to the OEM sized nipple for the rear 1948 cylinder head and found it to be about .024 to .025 oversized.
The inner thread for the oversized hole in the front cylinder itself is very clean and I'm expecting when/if I find a correct size nipple for it that it should install without too much trouble. Fortunately the incorrect removal of the nipple did not damage this one.
As for the rear head and the source of all the leakage, those inner threads had been damaged prior to removal as the nipple itself actually felt loose before I even removed it. Now if I had .010 oversized nipples for this one, this problem could may be resolved without too much trouble. It may require a steady hand, but I'm game for anything!
I intend to stick with the plumbing manifold regardless of what others say. I know I can make this work. It worked fine out of the factory some years ago, I'm certain I can make it work again. It may take some learning on my part to figure it out, but hey, I've always figured that if I do my own work on most of it, I'll know what to do if I end up on the side of the road. In fact, I came up with a good twist to an old saying: Be your own man, fix your own pan! ;D
Let me know when you get that number. Thanks for your help.

jester-

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