I can't drive 55

[MOTOV8R]

With no rear drive shaft you will know if it’s a rear end problem or a front end problem

How would I know?

If you can easily go over 45 mph in either of these tests then the disconnected axle is the problem.

Have you considered using a laser thermometer to check for hot spots after running it for a while, especially after trying for max speed. If it’s a power loss issue you should be generating a lot of heat somewhere.

 

[knuckle47]

Damn, the thinking caps are coming out now. These could be some very effective tests albeit a little work in mechanics energies involved. So many things that can be ruled out. @MatthewMcD your focus is intense so I know you will discover an oddity in this chain of events and everyone will be better for it if it’s that odd,

The level of involvement by the crew here is huge. Next will be a gathering in Austin for a full tear down, rebuild and Franklin BBQ dinner afterwards

By the way: how long has this been going on?

 

[MatthewMcD]

Damn, the thinking caps are coming out now. These could be some very effective tests albeit a little work in mechanics energies involved. So many things that can be ruled out. @MatthewMcD your focus is intense so I know you will discover an oddity in this chain of events and everyone will be better for it if it’s that odd,

The level of involvement by the crew here is huge. Next will be a gathering in Austin for a full tear down, rebuild and Franklin BBQ dinner afterwards

By the way: how long has this been going on?

I have only had it road worthy with new suspension for about a month. Before that I was afraid to get it going this fast. So it's probably been like this since I got it.

 

[MatthewMcD]

If you can easily go over 45 mph in either of these tests then the disconnected axle is the problem.

Have you considered using a laser thermometer to check for hot spots after running it for a while, especially after trying for max speed. If it’s a power loss issue you should be generating a lot of heat somewhere.

I haven't, but I can add that to the list.

 

[MatthewMcD]

Any difference if you drive with the choke on?

Haven't tried it, but now I have a Weber with an e-choke.

 

[MatthewMcD]

I have been hauling old vehicles home for over 50 years and as for rodent nests, I have seen some real marvels of engineering. Orange poly baling twine, burlap sacks, fishing line, you name it. All woven together. It's a long shot and probably not the case, but it happens, so I'm going with it. Pressing the 'other' button.

In that case I'll pull the muffler this weekend after I figure out a replacement hanger.

 

[MatthewMcD]

Yep, plugs for the air rail. Did they fit under the F-air cleaner bracket?

What do you need to see?

 

[MatthewMcD]

That's something that I hadn't thought of, from the video It looks like it has the stock exhaust manifold.
View attachment 3750154
Not sure if it would cause excessive back pressure but every one of these valves I've seen is stuck or rotted out.

Mine is gone.

 

[island45]

Not that you need more items on your list, but looks like you need a stainless plate in between the manifolds if you aren't gonna run the flap. That's a hostile environment for your aluminum intake manifold.

 

[pb4ugo]

You could cut the exhaust pipe b4 the muffler to open up the exhaust for testing purposes. They make band clamps to repair the cut once testing is done. An exhaust shop could weld it up the joint with maybe sleeve too. I'm not sure it's your problem though. They make several different types of clamps.

 

[Grayscale]

What do you need to see?

Is the air rail plug in the 2F head at cylinder number one protruding such that it is in conflict with the air cleaner bracket? It might not matter, depending on what carburetor you pair to the engine. My air rail plugs that I'm currently running are Allen head, and they don't protrude. above the holes. (edit) I see it is appears clear in post #104 (valve video).

I'm in favor of the stainless plate between the intake and exhaust manifold. These aluminum intake manifolds were vulnerable in a stock configuration, and not having that flap, aka 'heat control valve,' defeats the bimetal spring that was part of it. Two out of three of my intakes have a crack under the carb because of it. The crack will be enough to leak fuel onto the exhaust (headers) in into the exhaust manifold or header.

I'm confident that the wrong head is the issue to solve before any more tinkering.

 

[MatthewMcD]

You could cut the exhaust pipe b4 the muffler to open up the exhaust for testing purposes. They make band clamps to repair the cut once testing is done. An exhaust shop could weld it up the joint with maybe sleeve too. I'm not sure it's your problem though. They make several different types of clamps.

View attachment 3750208

Thanks, All I really need to do is cut off the lame hanger they created and go back to stock. Which I have most of, I just need a piece to wrap around the muffler pipe.

 

[MatthewMcD]

Is the air rail plug in the 2F head at cylinder number one protruding such that it is in conflict with the air cleaner bracket? It might not matter, depending on what carburetor you pair to the engine. My air rail plugs that I'm currently running are Allen head, and they don't protrude. above the holes. (edit) I see it is appears clear in post #104 (valve video).

I'm in favor of the stainless plate between the intake and exhaust manifold. These aluminum intake manifolds were vulnerable in a stock configuration, and not having that flap, aka 'heat control valve,' defeats the bimetal spring that was part of it. Two out of three of my intakes have a crack under the carb because of it. The crack will be enough to leak fuel onto the exhaust (headers) in into the exhaust manifold or header.

I'm confident that the wrong head is the issue to solve before any more tinkering.

Do you have any example of this plate? The spring is gone and the axel is frozen with rust.

Also, I am not familiar with what an "air rail" is. Are you talking about this intake manifold?

 

[MatthewMcD]

I'm confident that the wrong head is the issue to solve before any more tinkering.

That's not going to happen. I have a replacement '78 2F in the works, I am not planning on investing in this engine unless it's applicable to the new installation...like a clutch since I'll have it out of the chassis.

 

[brian]

to add insult to injury, this is to about 65.

 

[knuckle47]

If im not mistaken, the air rail was for a smog pump that was located on top of the manifold

 

[brian]

That's not going to happen. I have a replacement '78 2F in the works, I am not planning on investing in this engine unless it's applicable to the new installation...like a clutch since I'll have it out of the chassis.

compression numbers said thats not the issue

 

[island45]

Not sure what the 'squish' area is above a domed 2f piston and the domed head, but pick a cylinder at TDC on compression, back it up and slide the big end of a zip tie in there and advance the crank. if it goes right past, I would guess you have flat top pistons (and they DO look flat) with domed heads. Oh wait, it's too late to change my vote.

 

[Grayscale]

Do you have any example of this plate? The spring is gone and the axel is frozen with rust.

Also, I am not familiar with what an "air rail" is. Are you talking about this intake manifold?

At Cruiser Outfitters, Part# EGEXHRPE but, it doesn't appear to fit with the year of manifold, depending on how Frankenstein it is. Maybe you need headers, or need to fabricate the block-off out of stainless sheet if you're going to use the stock manifolds. The air-rail was a manifold for the smog pump. Late Fs and 2Fs forced fresh air into the exhaust at the ports in the head, it was for emissions.

That's not going to happen. I have a replacement '78 2F in the works, I am not planning on investing in this engine unless it's applicable to the new installation...like a clutch since I'll have it out of the chassis.

With the 2F-head, by using the (presumably) '68 intake manifold, and '68 air cleaner assembly it might keep you in the realm of non-stock carburetors, or a used F carburetor (one-barrel F). I know that the F intake manifold ('70) sits a bit more inboard than the 2Fs. Height might differ as well.

A possible game plan would be the "replacement" 2F, 2F intake manifold, headers or 2F exhaust manifold that matches the intake manifold, 2F carburetor, 2F air cleaner assembly, and restore the linkage-type torque-rod throttle, or convert it to cable-throttle (the air cleaner assembly is likely in the way) or employ a bell-crank throttle from a '73 or '74. Then, shake-down any leaks and hope that it runs tight. My inclination would be a proper head, headers or exhaust manifold block-off. However, I'm assuming that the Rochester can run a LC straight-6, if it was originally used on a Chevy straight 6 with similar or even greater displacement as the LC.

compression numbers said thats not the issue

Does this mean that a 2F head is compatible? Is it just a matter of piston, flat or domed, and the flat pistons were swapped for a domed piston? Could the four millimeters difference in cylinder-bore not matter? I figured that it was not able to expel exhaust gasses, having extra combust chamber volume with the early 2F head combined with flat-pistons from a '68 ('73 and '74 use a domed piston, which might work?).

 

[MatthewMcD]

At Cruiser Outfitters, Part# EGEXHRPE but, it doesn't appear to fit with the year of manifold

Found this: Heat Riser Block Off Plate - Fits 1969 - 1/1975 3-Bolt Style 4x Applications (EGEXHRPE) - https://cruiserteq.com/heat-riser-block-off-plate-fits-1969-1-1975-3-bolt-style-4x-applications-egexhrpe/

Not clear on what this mates to and what it is for.