Hi guys! I have a a quick question about the threads on my Offy intake: is the vacuum port 1/8 npt? I'm asking because it feels like its really tight when I try installing a fitting. Thanks!
The threads may be buggered by someone butting a S.A.E. I bolt in it. Run a tap through it. I found that Teflon tape helped when I put the fitting in
The catch is that the threading appears to be 24/inch (tested it very gingerly with a tap) but all the fittings I find are 27/inch (which is NPT).
READ YOUR POST THIS Afternoon, I was just bolting the four barrel manifold on the flathead I am rebuilding for my 51 Ford Convert. I had not gotten to fittings yet, so I thought I would take a look, and damn your right, that ain't pipe thread. After checking several posibilities, the only match seems to be a 7/16 NF bolt. Like they say, Whats up with that? Buflochp
I've got a brand new 4bbl Offy manifold and I'm not sure either?.........so many things to eff around with!
I've heard a few times already that the Offy new stuff is just FUBAR. It looks nice, and can work, but their are alot of things that pop up that shouldn't w/a "performance parts" manufacturer.
There exist fittings meant for a compression type fitting that have male threads that are close to 1/8 pipe in size but are something else...I never investigated any further in my junk fitting stash because I have no application for whatever they are. Medde this takes one of those...it would allow easy hookup of a type of standard automotive tubing.
My other thought was that because NPT fittings are slightly tapered, it would explain why they started in ok, but got tighter as they went. Could this have been the intent?
If yours is like mine, an 1/8 inch pipe fitting goes in the hole about 3/16" before it is big enough to fit the hole. I thought maybe a 7/16" banjo fitting might work, but after I found one I figered out it was 20 tpi. The only other idea I had was because the manifold is spot faced around the hole, that is usually done for O-ring seal fittings, I know they have a straight thread, but the only ones I could find were all bigger. Well if ya put 5 wraps of teflon tape on it and cross thread it in, I'm sure it will seal good enough for a vacuum line. It is part of a plot to make us all do things that someone else will find, So they can talk about us being Slobs behind our back. Buflochp Keep your stick on the ice. P.S. I am gonna call Offenhauser and have them send me a new hole.
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