Exhaust Manifold Replacement

[Danno1966]

Hi All...I. getting ready to replace the manifolds on my 350 Mag MPI...
I'm thinking I want some studs to help make the install easier. For this to work does anyone know the threads and how long so I can still get them out? 3/8 studs, right?
Second question, I have a 6 inch extention between the manifold and the elbow...will the gasket between the manifold and the extension be the restricted version? I've heard it is, but I've also heard it's unrestricted for the manifold to extention joint, but restricted from the extention to the elbow...anyone know for sure?

Thanks!
Dan

 

[achris]

... my 350 Mag MPI...

Got a serial number or year for your 350 Mag MPI?

 

[Scott Danforth]

Hi All...I. getting ready to replace the manifolds on my 350 Mag MPI...
I'm thinking I want some studs to help make the install easier.

why?

put the outer two bolts in a few turns, then drop the exhaust gasket in place

the outer two holes on the gasket are slotted to do this.

 

[Danno1966]

Got a serial number or year for your 350 Mag MPI?

OLO34262

 

[Danno1966]

why?

put the outer two bolts in a few turns, then drop the exhaust gasket in place

the outer two holes on the gasket are slotted to do this.

Because they are heavy, I'm old, and tight space... I know how to do it... I just want to slide them on studs rather than try to hold them while trying to start a bolt. Why not?

 

[Lou C]

if you want, take a new bolt for the manifolds to a hardware store, and have them match up the thread pitch, to 2 longer bolts. Get the 2 bolts, cut the heads off and cut a slot in the stub that's left. Then thread these in the first and last holes, slide on your gasket, manifold and install the remaining bolts. Last remove the 2 long headless bolts (why you cut a slot in them) and install the last 2 bolts.

 

[tank1949]

Hi All...I. getting ready to replace the manifolds on my 350 Mag MPI...
I'm thinking I want some studs to help make the install easier. For this to work does anyone know the threads and how long so I can still get them out? 3/8 studs, right?
Second question, I have a 6 inch extention between the manifold and the elbow...will the gasket between the manifold and the extension be the restricted version? I've heard it is, but I've also heard it's unrestricted for the manifold to extention joint, but restricted from the extention to the elbow...anyone know for sure?

Thanks!
Dan

I have had success in sacrificing 3/8" bolts by cutting off bolt heads of two and using them as piolets to control on and off removal of heavy exhaust manifolds. Just use hack saw to add a flat head slot onto stud ends. I replaced several spark plugs before figuring this out.

 

[tank1949]

if you want, take a new bolt for the manifolds to a hardware store, and have them match up the thread pitch, to 2 longer bolts. Get the 2 bolts, cut the heads off and cut a slot in the stub that's left. Then thread these in the first and last holes, slide on your gasket, manifold and install the remaining bolts. Last remove the 2 long headless bolts (why you cut a slot in them) and install the last 2 bolts.
View attachment 345207

very clean motor. Must be fresh water boat?

 

[Lou C]

very clean motor. Must be fresh water boat?

Nope 100% salt water here in Long Island NY. Kept on a salt water mooring for approx 6 month season each year. In that pic I had just installed reman heads and new exhaust so everything was freshly painted.