Exhaust manifold nut issue

[TylerB46]

Hey guys, I was trying to put the exhaust intake/manifold on my 230  engine, and the four nuts that fit into the groved brass washers. I can not get those nuts started on the studs to save my life. Are they normally this difficult or did I just get a bad batch?

[Don Coatney]

Are your studs coarse thread where they screw into the engine block and fine thread where the nut attaches?

 

[TylerB46]

19 minutes ago, Don Coatney said:

Are your studs coarse thread where they screw into the engine block and fine thread where the nut attaches?

 

They sure are. Whole thing came as a manifold stud kit for a 230 from vintage powerwagon.

 

[TFC]

Had the same issue with the kit I got from VPW, I ended up chasing the threads of the nuts with a tap, they installed fine after that.

[TylerB46]

48 minutes ago, TFC said:

Had the same issue with the kit I got from VPW, I ended up chasing the threads of the nuts with a tap, they installed fine after that.

I’ll try that, they’re 3/8-24 right?

 

[Branded]

Got do your local parts house and get the correct studs, they’re readily available.

[TylerB46]

I got them on, just chaced the threads with a tap like TFC said and it worked great

[johnsartain]

I had to run the nuts on to a same size stud backwards first then they were able to start the right way.

 

[lonejacklarry]

I would question the strength of the nut holding ability.  If the diameter of the nut was correct but the thread pitch differed then running a tap through to correct the problem removed a lot of metal.  For the price of the new nuts it would be a no brainer for me.

[TylerB46]

3 hours ago, lonejacklarry said:

I would question the strength of the nut holding ability.  If the diameter of the nut was correct but the thread pitch differed then running a tap through to correct the problem removed a lot of metal.  For the price of the new nuts it would be a no brainer for me.

The nuts are cone shaped, so the problem was that they were too narrow, so running the tap down them just opened them up enough to fit onto the stud so they would thread. 

[kencombs]

31 minutes ago, TylerB46 said:

The nuts are cone shaped, so the problem was that they were too narrow, so running the tap down them just opened them up enough to fit onto the stud so they would thread. 

Probably tapped at the factory w/a taper tap and not run deep enough.

[johnsartain]

21 hours ago, johnsartain said:

I had to run the nuts on to a same size stud backwards first then they were able to start the right way.

 

Running them on backward, spread the cut/castellated part a bit, enough it was easy to thread onto the manifold stud. Tapping it would have worked equally as well but I didn't have a fine thread tap. I found that when I looked at the nuts, they seemed to be closer at one end of the split which meant to me that they had been formed that way for a tight fit. Running them on backward was just enough to spread it back to allow it to start on the stud.