Cannon Intake Manifold rod end possible solution

[Zedyone_kenobi]

Blue, great points. and WONDERFUL drawings!! THAnks bud.

I made an extensive effort to get the angle of the actuation arm the same as the rod on the Weber. You cannot see it, but right now they are parallel. However, the stroke on the throttle cable rod has always not been ideal. The positions of the cables/push/pull rods on the rods I have played with extensively. I had to give up some mechanical advantage due to the fact that I was trying to balance the spring force with the rod flexing. I have a 3/8" rod coming in. It will replace my 5/16" rod I am using now. I need to take a video of the rod flexing when I touch it.

[240260280z]

I put the pics and suggestions up reluctantly (and more so for others who stumble across this) as I know you (and skills and attention to detail, and striving for excellence and.... the list goes on and on and I have seen that wonderful machine in the flesh!!!

Shortening A and experimenting with an eccentric to make the pedal stroke non-linear could be fun for you, I, CO, LaZeum and a few other geeks on this forum to explore

[Captain Obvious]

I got a few more, but you get the gist

I don't get any pics... Just this:

I'm assuming there's a problem on my end?

[Zedyone_kenobi]

NO I am getting that too, but it worked earlier.. I have no idea why. Flickr has been dead reliable in the past. Let me go check my links again.

[Zedyone_kenobi]

[Zedyone_kenobi]

Well drat I managed to get an hour of time today to get into the garage and found out my new beefy linkage kit was a bit too beefy. HA.

It seems the Cannon manifold has 5/16-24 threads in it. THE rod ends in my new kit use 3/8" threads. I have looked everywhere and it seems that rod ends that accept a 3/8" shaft ONLY come with 3/8" threads.

I may have to drill the manifold and tap it to to accept 3/8" threads. Drilling into the manifold is not my idea of fun, but I figure it can be done.

and if I mess it up well then I will have to take it off and get it done again anyway.

Wish me luck.

[Captain Obvious]

I may have to drill the manifold and tap it to to accept 3/8" threads. Drilling into the manifold is not my idea of fun, but I figure it can be done.

How about modifying the threaded portion of the new 3/8 rod ends down to 5/16 instead? Drilling & retapping the manifold is hard to undo, and you could always buy another set of 3/8 rod ends. Lathe would make quick work of that. In a pinch without access to machine tools, you could probably even use a file to cut them down to size before running a 5/16-24 tap over them. How good is your eye?

Nice pics of the linkage BTW.

[Captain Obvious]

So about that third center mount... I assume that the direction of "problem" you were originally having was fore/aft (as opposed to up and down), since the rod ends have adjustable height. I would HOPE (and assume) that the manifold manufacturer located and drilled all those holes on a machine capable of holding a suitable tolerance to use all three mounting points.

You are threading a non-precision shaft into a (hopefully) precisely located hole, and then locking it in place with a non-precision nut which may or may not pull straight up on the shaft. I'm not surprised you can't get three of them in enough of a line to have the shaft rotate smoothly. How about a thin tapered washer under the center mount lock nut to cant the rod a little in the direction of your choosing? You could test the concept using by slipping a feeler gauge under the nut on one side and snugging up the nut.

But before you do any of that... It looks like they did not machine the top surface of the mounting bosses? Make sure there isn't simply a thread burr kicked up or something that is preventing a perpendicular face. Me? I would have machined the tops of those mounting bosses normal to the threads.

Just throwing out some ideas... Maybe something will stick?

[Zedyone_kenobi]

I thought just that Captain. Well sort of. When the manifold was off and I was test fitting the original rod, I had all the rod ends lose without any lock nuts on them at all. I swapped around rod ends, and tried all possible combinations. My middle was still a good bit more than 1/16th of an inch off at least regardless of how lose it was or what order I put them in. It was very discouraging. I can tell you by the looks of the Cannon manifold that it is so cheaply made ZERO finishing or quality control was done. I had to remove flashing from the runners on both sides. The webbing on the outside of the runners shows the sloppy casting. The last hole by #6 cylinder required 'persuasion' for it to sit flush on the gasket. I am not the only person who has had issue with the Cannon Manifold. I get the impression the FET or Kameari are leagues above in quality. The cannon is built to a price point.

I was able to get my fore and aft rod end holes drilled (.334" drill) and tapped them with a 3/8-24 tap. The Rod ends are extremely close to parallel with each other and they appear to be perpendicular to the surface of the manifold. When you are only using 2 rod ends, the need for perfection on linearity is not nearly as important. I used a set of calipers to ensure they are sticking up the same height above the manifold within 0.060" of an inch anyway as best as I could measure.

When I inserted the 3/8" rod, it barely moves when I apply a load to it. It also spins freely in the rod ends.

Also the rod ends supplied with the Weber kit had a metal ball riding in a phenolic 'race'. That plastic bushing if you will had developed some slack in them that was not there when new. They had also become extremely stiff as well. I know that seems like a contradiction, slack but stiff, but that is what they feel like. Sort of like the worst of both worlds. The new rod ends are a different story. They are all stainless and are extremely smooth and of higher quality.

The metal on metal of the rod ends and the new actuation rod feels almost lubricated its so smooth. I will attempt to attach the lever arms tomorrow if my new baby boy lets me. He does not give me much free time haha.

[240260280z]

Not that you want to go there but here is a similar experience in battling a Cannon manifold:

I had to reverse the mounting on a 510 manifold this past autumn. The PO had the linkage under the manifold.

The top of the manifold had two bosses with already-drilled holes for vac. advance and brake booster vacuum (though the 510 had no brake booster).

The top holes were too large for the linkage's rod ends so I used a larger barbed brass hose fitting, cut off the barb, tapped the intake and threaded the rest of the barbed fitting into the larger hole then drilled and tapped the centre of the barbed fitting to accept the rod end. The barbed fitting was essentially a step down adapter.

Everything worked fine.

[Captain Obvious]

It was very discouraging. I can tell you by the looks of the Cannon manifold that it is so cheaply made ZERO finishing or quality control was done.

Stuff like that burns me up. Sometimes you buy stuff and everyone knows it's a "kit", and part of the fun is the finish work. But I'm assuming those manifolds aren't marketed like that...

Anyway, it sounds like the changing of the mounting hole threads went well. Let's hope that a stiffer linkage and better end bearings make the necessity for a center mount a moot point. Get the torsion springs on for the return and you may not miss the center point at all.

[240260280z]

Back at the Webers and learning more and more. Here are a few more tips:

1. The axis of the long rod running across the manifold should intersect the hole in the fire wall bracket where the shepherd hook loosely fits. Adjust the three heim joint heights so that they are all the same and inline with the fire wall bracket's hole (like in the photo below).

heim joint Shepherd rod inline with rod

2. The hole you choose on the rod-arm determines the throw and mechanical advantage. The rod-arm is a lever and the further out the adjustable-arm is connected, the harder it is to press the pedal but the less pedal travel is needed.

The distance "A' in the drawing below represents the selected rod-arm hole to the rod distance. Most seem to use the furthest hole at the end of the rod-arm, like this (look at left side of left most carb):

Rod Arm Connected at Furthest Hole

..... but the weber drawing below seems to indicate that "A" is slightly longer than "C" (C is ~37mm on the 151 DCOE 151's I am working on).

I have the cannon part below. The hole distance to the rod hole (on centers) are:

end hole: 60mm

middle hole: 47mm

inside hole: 35mm

Presently, the car I am working on is set at 60mm and the DCOE has the common problem of not fully returning to idle stops. I plan to increase the return to idle force by using external springs so I will need more mechanical advantage to overcome these new springs.

I will try the 35mm hole first to get more mechanical advantage and have a further foot travel then move to 47mm for experimentation. More foot travel should provide finer control of the throttle and hopefully not too much so as to be unnatural or tiring.

3. The other detail in the weber drawing is that "A" is parallel to "C". The adjustable-arm should be adjusted so as to make "A" parallel to "C". All three adjustable-arms should be set to the same length. An easy way to do this is to clamp two parallel bolts in a vice and place each adjustable-arm on the bolts one at a time to be the same distance.

4. Try to ensure that the rod-arm is directly above the corresponding arm on the carb. Ensure nothing binds or rubs.

5. Set the accelerator pedal stop (on the floor under the pedal) so that it prevents the foot pedal from over torquing the weber throttle plates and twisting the shafts.

Edited July 29, 2013 by Blue