72 3.0 CS 2240344 Restoration

[ScottAndrews]

This is a partial repost from the rocker drain holes thread.

I took a few more photos of my rear rocker assembly, and sorted out what is what in the tangled rusty mess. The right rear rocker had a small rust bubble, that I found once I took the crusty rocker trim covers off. That was nearly 20 years ago, before life and jobs, and multiple other home and boat projects got in the way of car restoration projects.

Here is what I found back then:

I decided to cut into this to see just how bad it was. At the time I did not really understand the structure of the car, and specifically the complex structure right around the A, B, and C pillars.

The rocker has three primary components: Inner rocker (which the floor is attached to on the sides), what I call the "zig zag beam" (which is a flat piece with perforations and zig zag indentations), and the outer rocker cover (this is itself covered up by the rear quarter panel in the back, and the fender up front). Together these three parts form a tubular beam that runs from the back of the front wheel well, to the front of the rear wheel well. At the pillars there are pieces that attach to the zig zag beam to form the vertical elements of the car (front door pillars, door latch pillars and rear wheel arches (which eventually become the C-pillars). .

Here is what was under this rusty spot at the back end of the right side rocker (some of the really crusty stuff has been removed in this pic). Since it is a bit hard to tell what you are looking at, I have labeled the components.

Here is a better view from the bottom looking upwards:

Fortunately the zig zag beam and the c-pillar are actually solid, just rusty on the surface. The rocker cover is another story.. nearly totally gone at this area. It gets stronger as you move forward. You can also see the culprit in this show, which is the drain tube from the C-Pillar roundel vent. I am surprised how much water comes in there, but I guess it is from road mist blowing around the car in the rain, and maybe from overly aggressive washing. At any rate, the hose drains into this area, which is supposed to drain out of small weep holes in the bottom of the rocker assembly. I have not checked these yet, abut I suspect they are clogged.

I also found a surprising amount of dirt and grit, mixed with rust flakes lodged in crevices in this area. I am not totally certain how this gets in there, but it is possible that some of it comes in the drain tube, and some falls down the hollow c-pillar. 50 years is a long time to accumulate a few tablespoons of grit. I think I had at least 3/8 inch of similar grit up in the "shelf" in the front wheel well.

Fortunately for me, I think I can cut the quarter panel back below the lip where the rocker trim cover goes, so the repair should not be visible. It will involve removing the lower 4-5 inches of the quarter panel from the door to the rear wheel well, removing the rusted rocker cover, cleaning the beam and everything else I find in there, treating everything with POR 15, and then welding in a new section of rocker cover (shown in a post above), and then welding on a replacement section of the quarter panel.

The other side is not as bad from the outside, but given how bad this side was, I'll at least open that side up, and probably do a similar repair.

 

[ScottAndrews]

Been discussing floor repairs with @Mike Pelly (super nice guy!), and have ordered a set of his floor pans. I only need to replace the front floors.

The driver's side should be a pretty simple cut and paste job, since the rust is mostly located in the recess in the middle of the floor. The passenger side is much worse. Mike suggested that the location of the inner corner close to the exhaust down tubes tends to heat and cool the floor metal, accelerating its decay.

Here is a shot of the passenger floor with the approximate outline of the section of pan I'll be using (solid yellow line). The dotted line shows the part I'll have to fabricate, probably from the unused portion(s) of the floor pan(s).

I'll need to remove the heater and the trans tunnel insulation, and brave the import tariffs before diving into this, so it will be a few weeks before I fire up the welder..

 

[HB Chris]

If the a/c drain is plugged which is very common the water that collects can slosh around and spill into that area as well. I think that was the case in my first coupe as the floor pans were good.

 

[ScottAndrews]

If the a/c drain is plugged which is very common the water that collects can slosh around and spill into that area as well. I think that was the case in my first coupe as the floor pans were good.

Yeah, Mike P suggested it was a combination of AC condensation and heat that was the real culprit.

 

[jmackro]

First issue is the exterior finish (clay? carved wood? ) the second is the abrupt change in the flow axis from the throttle body to the manifold...

I'm no authority on intake manifold design, but the angle change between the throttle body and manifold doesn't trouble me much. Note that the mounting angle allows the injector axes to be aligned with the manifolds and head ports. While there might be some resistance as the air is forced to turn the corner, I'm guessing that the resulting hp loss would be negligible for anything short of an all-out competition application. And maybe the throttle bodies need to be aligned horizontally for the air filter to fit in the available space.

The manifolds' exterior finish does look stone age; I wonder how well the inner bores are finished?

 

[ScottAndrews]

I'm no authority on intake manifold design, but the angle change between the throttle body and manifold doesn't trouble me much. Note that the mounting angle allows the injector axes to be aligned with the manifolds and head ports. While there might be some resistance as the air is forced to turn the corner, I'm guessing that the resulting hp loss would be negligible for anything short of an all-out competition application. And maybe the throttle bodies need to be aligned horizontally for the air filter to fit in the available space.
The manifolds' exterior finish does look stone age; I wonder how well the inner bores are finished?

Yeah, I'm no authority either... From a physics perspective, I would think the abrupt angle change would cause turbulence, which might be good from a mixture uniformity perspective, but a smoother flow would probably cause better intake efficiency (less drag) in the same way that porting and polishing helps with that last little bit of performance. In any case, an old engineering principle seems apt here. If it is beautiful, then it probably also works well. If it is ugly, then it probably doesn't (I just made that up)...

 

[ScottAndrews]

So here is the very first 3D prototype manifold. This is a 30 degree unit made from my initial model, which I messed up, so the primary flow tubes did not render as tubes in the print (I knew this going in). I have since modified the design to a 25 degree bend, which gives a slight tilt toward the engine for the carbs (recommended by Weber), and also fixed the rendering issue.

I am very impressed with the surface quality of these parts! I had them printed by a prototyping company called Xometry. This one was printed in the US and cost about $50. The 25 degree units are in print now. The off-shore print cost for those was $70 for three units. Can't wait to see those!