Seriously warped manifold

[65standard]

I have a used manifold on the way. Should have it Monday

[kazoocruiser]

Originally Posted by 65standard

The gasket only fits the head this way. Cutting in sections will not help the manifold align with the head. This gaskets has the smooth side toward the manifold. Can’t reverse it.

Also the intake and exhaust manifolds bolt together. There are 3 bolts under the carb area. I can’t undo these as there will be a big gaping exhaust leak. The top of the exhaust manifold is wide open as to preheat the carburetor.

I thought the same thing, just separate the two manifold to align them to the head better.

Let me see if I understand you correctly. It seems the issue at this point is when you connect the exhaust manifold two outer bolts, the center 4 ports are non-aligned with either the manifold ports or the gasket itself in its un-modified state. It also forces a gap into the space between the exhaust manifold stove and intake manifold. The intake manifold has no problem lining up correctly.

Apparently the rear exhaust manifold bolt was missing when you took the manifolds apart. If it had backed out and left the manifold unsecured, heat from the exhaust pulses would have forced expansion into the manifold allowing it to creep out of line.

With you restoring those two bolts, you now have a misalignment resulting in gaps that must be sealed.

The four exposed ports can have the gaskets shifted to step the gap. That might mean modifying your factory gasket to allow for that. The head should have enough material around the exhaust port to allow for some mismatch.

That leaves the stovepipe to the intake with a gap that a single gasket won't bridge. So, can you use two or three of them, with longer bolts if necessary?

The next more expensive option is to maybe find a place that can re-arch truck springs. They might be able to help you, or maybe a machine shop with a method to heat up iron to reform it. That option might cost more than a replacement, and carries the risk of cracking the manifold anyway.

Interested in seeing how this problem gets resolved.

[kazoocruiser]

Originally Posted by 65standard

I have a used manifold on the way. Should have it Monday

This got posted while I was writing my last response. I slow typer.

[RichardJ]

>>The engine was together missing the last exhaust bolt.<<

There never was nor should there be a LAST exhaust bolt.

The end hole on both end of the head should have a short locating pin. The pin is threaded into the head, but no threads are exposed.

The third hole in, from each end of the head should have a threaded stud. These heads came from the factory with the two studs, but for some reason, most are now missing them. I think the head rebuilders remove them and never bother to replace.

This is an original threaded stud along with a long and short clamping bar.



I'm not sure how you are trying to use that gasket, BUT the metal side should go OUT, toward the exhaust manifold.
The gasket is not symmetrical, end-for-end. I suspect it lines up against the head in Post #25 only because you have 6 bolts holding it straight.
Roll the metal side OUT, flip it end-for-end and see if your 6 bolts hold it straight.

It that lines up as it should, then try installing the manifolds individually. If you don't want to install the correct studs, cut the head off two bolts and use them as temporary guide pins to see where any problem exists. Use the third hole in from each end as the factory did and the intake should be held correctly.

>>There are 3 bolts under the carb area. I can’t undo these as there will be a big gaping exhaust leak.<<
There is a gasket that goes between these two manifolds.

With regards to the 2 original short end-guide pins, if you ever install tube headers, those should be replaced with threaded studs.

[RichardJ]

Without at least the original two threaded studs it is difficult to hold the two manifolds in the correct location for installation.
I installed the stock length studs in all 8 holes in the head when I installed the headers.
In this picture, there is not one bolt holding the manifolds to the head for this mockup. The studs supporting everything makes for a very easy installation.

[65standard]

Originally Posted by kazoocruiser

Let me see....

Apparently the rear exhaust manifold bolt was missing when you took the manifolds apart. If it had backed out and left the manifold unsecured, heat from the exhaust pulses would have forced expansion into the manifold allowing it to creep out of line.
...
.

I agree with this and that could really be the only way it got warped. The rear stud or bolt was left out and the constant heat and cooling cycles allowed the rear section of the manifold to creep up 7/16”

I will install the replacement manifold with two studs on each end and the correct brackets as per factory specs.

Just for fun, I will try to straighten this manifold back in the shop on Monday. Yes, I am a professional metal shaper and steel fabricator. Cast iron isn’t our thing, but I’ll experiment on it.

[Steeveedee]

OK, I can see how the thing got warped, I guess. I've never seen one that bad. You're going to have fun straightening it, because I'm sure that you know that you're going to have to keep the manifold flat where it meets the gasket while heating and bending. It'll be interesting to see how that comes out! Show us how you do, even if it breaks. In fact if it does break, we can all stand around with a beer in our hand, saying, "Yup, that broke real good!" Yes, I am easily amused.

[kazoocruiser]

Originally Posted by 65standard

I have a used manifold on the way. Should have it Monday

If the manifold you get is not going to work, I saw this thread

http://67-72chevytrucks.com/vboard/s...d.php?t=779846

Looks like he has a manifold available.