Exhaust Manifold Questions

Hello all. Separated my intake from my exhaust manifold this evening. (broke 2 studs )

I appear to have a crack... I'm wondering what best practice is to seal it?


Also, can/should I remove the seized emissions(?) gear shown below? -I don't live somewhere that it might bite me inspection-wise.


Thanks in advance!

 

That is a functional part, in that it controls the warm-up and temperature of the intake.

Cracks in manifolds are difficult. Can you replace it?

 

I could replace it... but if I can fix it I think I'd rather save the $$.

As for functional... the part in question is solidly rusted in the position that you see in the photo. This rig will be a 3 season affair when complete... do I need to be concerned with warming the intake?

 

Get it working, you may want to take a look at the exhaust ports in your intake manifold too. Mine were plugged up with carbon/rust/crud.

 

IMO it's unrealistic to think about repairing a cast iron exhaust manifold that is cracked, if replacements are available. The manifold gets too hot for any sealing material you could apply. Weld only - grind out the crack, nickel rod, preheat the manifold to rocket hot, weld, cool slowly. Way too expensive for this common a part - discard and replace. Repop manifolds are available. Or change to the '81 or later 2V aluminum intake and matching smoother iron exhaust. They will bolt on, and you can run a 2V carb - the Motorcraft 2100/2150 or Holley-Weber are the most popular choices. I am running the later manifolds and a 2100 on my J10.

As mentioned, the flap is more about cold-weather drivability than emissions. It warms the intake manifold and keeps the gasoline from condensing on the cold manifold. It'll be there on the repop manifold. The later manifold replaces the exhaust-powered heater with an electric heater in the intake manifold, which you can choose to connect or not.

 

IIRC there are no passages in a 232/258 manifold, or any other inline engine where the intake and exhaust are on the same side. Those passages are used for V-type engines. Instead, the exhaust blasts directly at the intake manifold under the carburetor. There could be an EGR passage with a 258, but a 49-states '73 likely does not have EGR.

The OP's old manifold is missing the bimetal spring that closes the flap when the engine is warm. That was a service part, but I think you're never going to find it separate from the manifold today. I expect the only way the flap will ever work is using a replacement manifold.

 

Perhaps this is a good excuse to (re)read Tim Weaver's 4.0 head article...

 

If you went carbureted with the 4.0L HO head, IIRC you'd use the '81-up aluminum intake and the 4.0L exhaust manifold, which is more like a tubing header.

 

Well... the intake is soaking in toilet bowl cleaner ( Focker did it? ) and will be repainted once clean.

aaaand I should have my new exhaust manifold (new, eBay, $140 shipped) in about a week.

Trying to stick with the plan:

Underpinnings/Frame: NOW
Body that isn't bolt on: NOW
Tranny issues (2nd gear pop-out & throwout bearing): NOW
Engine and bolt on (gauges/seats/etc): piecemeal LATER. (engine is tired, but sound)

I wanna drive this thing before it's cold again.

As always, appreciate the replies.