Offenhauser 6x2 Gurus ! May I have your ATTENTION please !

What type of thread are the indicated holes ? Anyone know for SURE ?

 

Looks to be 1/8" npt and 1/4" npt

 

Thanks saltracer ! I forgot to add...I already tried a 1/8" NPT fitting in both holes but it does not fit.1/4" NPT is way too big.I have 1/4" NPT threads on my Moon tank,no way.

 

I bet dmarv would know for sure but I understand he's busy with other stuff.

No 6x2 gurus on here ? Please !

 

Can you run a tap in them?

 

I don't even know if this exist but 3/16 NPT?

 

I would say to get out your tap set and then you can figure it out more easily.

 

coil bracket?

 

carry it in to home depot and start pullin bolts, thats what i do

 

Thanks much for your suggestions guys.All of them make sense for sure but I don't have a tap set available and I can't just walk to home depot either cause I'm from Germany...I'm a Kraut...a Fritz...a Bratwurst ya know ?

Always wanted to purchase a US-tap set.I better do it now.Still look out for some Offenhauser 6x2 owners anyway !

 

The hole on the left is water,the one on the right vacuum.

 

DOH! didnt notice that, sorry.

 

Gotta bring this back to the top again.I could imagine these two holes have probably the same thread on every Offenhauser manifold,not just the 6x2.So everyone who runs a Offenhauser intake manifold is asked for advice.I'm thankful for any kind of help !

 

My Offy 6X2 manifold has those locations center spotted, but not drilled and tapped. So I'm ASSUMING someone did them for their application - so could be anything. Here in the US it would be common to use the 1/8 NPT and 1/4 NPT you say does not fit.

 

Thanks for your input Jim.The manifold is brand new,completely stock,just polished,nobody ever touched the threads after it left the manufacturer.I'm gonna ask some Offenhauser dealers too,also PM'ed dmarv.

 

Some GM cars used 5/16" hollow studs for vaccum. could be for a 5/16-18 hollow stud

 

If you have either vernier or dial calipers use the ID measurement side of the caliper and measure at the top of the hole and at the bottom of the hole, if it is smaller at the bottom then it is definately a pipe thread, next do a google search for NPT taper amount for different sizes of pipe threads. You can also do a count of the threads and divide by the depth of the threads. If its standard NPT you will have x number of threads per inch. Again, google it and you will find the number of threads per inch and the taper for all sizes, standard and metric.

 

The smaller thread on the head flange area is 5/16" USS (coarse) threads, same as the carburetor mounting holes. The hole on the rear crossover by the Offenhauser logo is 3/8" USS (coarse) threads, same threads as the distributor hold down hole.

Dan Marvin, Owner
Exeter Auto Supply

 

the vacuum one is 1/4 npt, and the water is 1/8npt, i think from the polishing they just got bunged up a little, get a us tap set, and tap away.

or if they arent thats what theyd be when id be done with it.

jeff

 

Dan is the man ! Problem solved.

Thanks again for everybody's input,it's really appreciated !