79 Exhaust manifold...options?

[Fiatlanta]

I'm beginning to understand the whole "mission creep" that these cars seem to be famous for, lol. A leaking heater valve turned into a hunt for a coolant leak which has now turned into wondering what options I might have with exhaust manifolds...

Long story short, tried to get a little more room to mess around with coolant hoses by taking off the heat shield...one bolt already had it's head sheared off and yeah, I twisted off another one under the distributor. The bottom bolt came out just fine, fwiw. The top left bolt twisted off nice and flat, so I think I could drill into it and get it out, but the top right, which was done before I got the car, broke off kinda jagged, so drilling it out isn't really an option with my tools and skill level.

So...I thought hey, this might be a good opportunity to look into upgrading. I'm trying to keep the car more or less stock whenever possible, so I thought maybe, similar to the intake manifold, there might be a reasonable upgrade simply by installing a part from a previous model year or something.

The other option I am considering is taking it to a machine shop and having them drill out the two broken bolts, rethread if necessary, and cleaning the thing up real good before reinstalling.

Either way, the heat shield itself is going to get sand blasted and repainted after it all goes back together.

Thoughts?

Thanks.

[kmoses]

What exhaust manifold do you have now? A 4-2 or a 4-1? The 4-1 has a round boss at the bottom of the exhaust manifold where the downpipe attaches and the 4-2 has a flange with studs to attach the downpipe. The 4-2 is what you want.

[Fiatlanta]

I'll take a look at it, but from what I can tell, it's the original manifold, so whatever that is supposed to be.

If that's the case, I'll look into getting the bolts properly drilled out and refinish the thing.

[bobplyler]

My heat shield has been gone for over 2 decades.

[ORFORD2004]

Use the welding nut trick to remove the stud.

[Exit98]

My heat shield has been gone for over 2 decades.

Mine too. You don't need that heat shield, don't worry about it.

Yeah there's some heat and I've heard some say that their plastic coolant bottle melted a little but I haven't had that issue in over 5 years.

If your manifold isn't leaking and only the bolts for the shield are sheered off then no harm no foul.

If and when you have to pull off the exhaust manifold then you can get it sandblased and powdercoated. But if everything is tight right now don't go fooling around down there. There's a high probability that the manifold studs and the downpipe studs, at least a couple of them, will sheer too if you try to remove them. I had a real tough time getting a broken one out of my head. I got lucky, otherwise I would have had to pull the head and send it out.

Your stock exhaust manifold is a 4-2-1. That's good. If the engine has been de-smoged already your next step is a better carb. I have a 34 ADFA which is great but there are other choices as well. There are plenty of threads on the topic.

[Fiatlanta]

Yup, the desmogging has started. I have a single plane intake manifold already. Looking at carb options now...leaning toward a 32/36...although I can't use the stock air cleaner then, I don't think.

Thanks for the input everyone.