Bolts or double threaded bolt for exhaust manifold?

[farmalldave]

I had to replace my c301 engine in my old farmall 806. I always make sure to take pic before tearing into something but my father got sick and passed so I ended up loosing my pics some how . So after couple years I'm finally working on getting the 806 running again. I have a c301 out of an old combine. I'm finally at the point of putting the exhaust manifold back on and I can't figure out if I use bolts of those double threaded bolts. I also had the head rebuilt so if it does require those double threaded bolts I don't have them. Any help would be appreciated. Are these the bolts with the thick washers that are used to attach the manifold. Yes bolts are going to get cleaned before installation.

 

[the tractior vet]

The intake and exhaust are held on by normal grade five 3/8th bolts with HEAVY flat washer , not as to length i know them when i see them , some where around 2 1/2 inches or So , never put a tape to them just gather them up out of a five gallon bucket and hang the manifold . Comes from YEARS of working on them . You could tear that whole tractor down , throw ever bolt into five gallon buckets and i can put each one back where it goes . Yep we have done that over and over again.

 

[farmalldave]

The intake and exhaust are held on by normal grade five 3/8th bolts with HEAVY flat washer , not as to length i know them when i see them , some where around 2 1/2 inches or So , never put a tape to them just gather them up out of a five gallon bucket and hang the manifold . Comes from YEARS of working on them . You could tear that whole tractor down , throw ever bolt into five gallon buckets and i can put each one back where it goes . Yep we have done that over and over again.

Are the bolts in my picture the ones you use they have a very thick washer.

 

[Jim.ME]

I had to replace my c301 engine in my old farmall 806. I always make sure to take pic before tearing into something but my father got sick and passed so I ended up loosing my pics some how . So after couple years I'm finally working on getting the 806 running again. I have a c301 out of an old combine. I'm finally at the point of putting the exhaust manifold back on and I can't figure out if I use bolts of those double threaded bolts. I also had the head rebuilt so if it does require those double threaded bolts I don't have them. Any help would be appreciated. Are these the bolts with the thick washers that are used to attach the manifold. Yes bolts are going to get cleaned before installation.

What are you calling "double thread bolts"? Do you mean studs? Studs are straight rods, either threaded full length with one thread or partially threaded from both ends and they may use different threads on each end. They generally thread into a base, such as an engine block, then the component such as a manifold is slid on over them and held in place by a nut (often with a washer between the component and nut) on the exposed end of the stud. Head bolts are sometimes replaced with studs.

Bolts as you have will work on the manifold or you could get studs that will work.

 

[Mrfred54]

Yes, those are the bolts. They are special bolts, wouldn’t recommend wire wheeling them. They are copper coated to prevent seizure to the cast. Don’t want to remove the copper coat for future removal. Buy new

 

[560Dennis]

Heavy washer is used to apply pressure equal on each tab of the manifold for adequate sealing.
If you get studs ( double bolts) they are available with 3/8 - 16 one end and 3/8-24 pitch so be aware.
I prefer fine pitch on the outside for easy nut removal and torqued pressure install is easily achieved correct.
Looking at bolts in Photo. I suggest you use (clean out ) flat bottom four fluted tap on each of the blind tap thread in your engine head. That way you do not get a false torque when installing gaskets.
With studs it easy to support the manifold at assembly ( a fatigue saver at factory assembly ) . That way you have two hands free to in stall washers, nuts and thight huts with wrench.