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Looking for a replacement for my broken brass external water bypass fitting for 303. This screws into the front timing cover of my 1949 Olds 88. Ive been told its 11/16-18 female tube thread to 1/4 NPT male. This is an inverted flare street elbow.
Last edited by maineolds; January 21st, 2021 at 04:22 PM.
I thought that we just went through this a few weeks ago. If you have a steel line with a "flare nut" that spins freely on the line, it can't be a pipe thread. A pipe thread seals within the contact area of the threads. Your steel line is flared on the end to seal against the raised seat at the bottom of the female threads, like a fuel line. Didn't you order and receive a fuel pump fitting for some other application that appeared to be correct. What happened? Asking for the incorrect fitting again won't get your car fixed.
Rocketman269, you're absolutely correct. My struggle has been in part due to my incomplete knowledge. When I looked originally for the replacement, I and others thought the part I that I needed was a 90 flare fitting that was 3/8x1/4. Often times this kind of fitting is known as an extruded street elbow. I eventually found that part made by a company called Hillman (part number 58334). I posted that on this forum so others could better find what they need in the event they broke one as I had. Sadly, while the Hillman part is similar, is isn't exact. The same could be said for the Corvette fuel pump fitting (1963-1966, 1970-1981) that was recommended.
The OEM copper line that attaches to the fitting I'd found is a bit larger than 3/8". I mistook the female part of the fitting as a 3/8 fitting because I used a tapered pipe to gauge the size. I didn't realize it was tapered at the time. A local hydraulic supply manufacturer looked at the OEM pipe and fitting today and told me it was 11/16, not 3/8. So I'm right back where I began. Looking for something that seemingly cant be found... a 1/4" NPT male thread x 11/16" tube female thread with inverted flare.As always, I'm grateful for the help in learning about the correct terminology.
Here's a picture of the broken original, the OEM pipe it attaches to and the replacement that turned out to be incorrect.
Last edited by maineolds; January 21st, 2021 at 04:23 PM.
First off, that line that you are holding is not 11/16". More than likely the head of the flare nut takes an 11/16 wrench to turn it.That line looks to have a double flare, similar to a brake line. What was the issue with the new fitting that you are holding? Was it too small? Can you measure the diameter of the line with a caliper or micrometer to get the correct size? It may be 7/16", but I still believe that it's 3/8". Hang in there and we'll get this figured out. Thanks, Bob.
Using a digital caliper micrometer, the OD of the line measures: 0.436. I took measurements at various parts of the tube to allow for deformation. 7/16 is 0.4375 in fraction form. Considering all the measurements were around 0.4375, I believe it is indeed a 7/16" tube. A 3/8 tube would be 0.375
The nut takes an 11/16 wrench and has a double flare at the end.
The issue with the new Hillman fitting is that its too small. Its designed for a 3/8" nut, not a 11/16. The attached pictures show the difference in their receptacle size.
Thanks for doing this with me.
Here's the broken original fitting:
Here's the new Hillman replacement fitting:
I have been searching Weatherhead and Gates online catalogs, but neither makes a direct fit 1/4 NPT x 7/16 inverted flare adapter. If you can get a piece of 7/16" copper tubing and have one end "bumped up" to 1/2", they do have a combination that should work: 105x7 flare nut and 402x8x4 Male Elbow. https://www.eaton.com/ecm/groups/pub...t/pll_1015.pdf
What's aggravating is, when your beast was built, those odd size fittings were in common use and easily found. Not so much in the "modern" world. 🙄
I have several older wrench and socket sets that include sizes like 25/32 and 29/32 that nothing produced in last 50 years uses. But something, at some time, did.
I know right? I honestly wonder if that fitting is found on any WW2 era planes. It makes since that they would have an enormous over stock of those parts and that the auto industry would make the most of them. Who knows...
Agreed! And for what it’s worth, I’ve been asking on the other forums too. I can tell you one thing for sure, it’s not from a Jeep! I’m some what of an expert on those. This forum needs to be praised. Of all the forums I participate in, you guys are the best by far. Lots of “noise” other places. People that like to consider themselves knowledgeable until the rubber meets the road so to speak.
one way or another, that original part will be found!
January 21st, 2021, 02:23 PM
