How to replace a Cox .010 venturi mount?

xplaneguy Sun Jul 28, 2019 6:03 pm

Recorded this how-to video on replacing a Cox .010 venturi mount. I hope some folks find it helpful.

https://www.youtube.com/watch?v=_aj_tAELTfI

Marleysky Sun Jul 28, 2019 7:52 pm

You tube deleted my reply. Great video, super suggestion on using black tape to protect the collet when removing. The big “Oh No!” for me was at 5:20 when you inserted a wrench thru the cylinder to stop the piston from moving. Just because of the price and availability of these cylinder and pistons, I would never do what you did because it could cause a “burr” that renders the cylinder useless. I’d put a drop of oil between the collet and drive plate to ease the friction as it pushes the drive plate off, who cares if the piston is moving?
Just my 2 cents worth. Love your video, and look forward to meeting you and Kim someday at SMALL!

xplaneguy Mon Jul 29, 2019 12:25 am

Thanks for your reply and feedback, Marleysky!

Yes, I add a drop of Rislone before installing the drive plate as well. I was concerned about the video going too long, so cut out some steps.

I hear ya on the wrench. I haven't had to do that but in case someone needs to for any reason, that step was included, briefly. I would likely use a piece of scrap wood, if that step was necessary.

Have fun,
Tony

Oldenginerod Mon Jul 29, 2019 6:15 am

Rather than risking damage by inserting anything into the exhaust ports, I generally invert the engine with the exhaust port open, then fill the cylinder with oil. Rotate the crank until the piston closes the port, trapping the oil, and you now have a hydraulic lock preventing the engine from turning. Cylinder and piston will not be damaged this way, but too much heavy-handedness could possibly bend a rod or break a crank pin. (Most unlikely unless you turn into the Hulk.)

**Cribbs74** Mon Jul 29, 2019 5:15 pm

Thanks for posting the video, same rules apply for all TD’s and Medallions. Personally I am not keen on using the collect to press off the drive plate. Not only can you grind down the collet by using it as a press, the wrench opening of the tool can easily slip on that notch in the collet gouging the collet and enlarging the notch in the process. Thus making it harder to remove. As you go up in engine size it gets exponentially harder to remove the driveplate using the collet.

I like using a sacrificial bolt screwed into the crank. Just a couple of hammer taps on the bolt head will free even the most stubborn drive plates.

In the end to each their own, not knocking your method whatsoever, it just has more risk. I do think the tape is a good idea!

Ron

KariFS Tue Jul 30, 2019 12:59 am

I think we have had this discussion here before, feels like deja vu all over again Smile

Anyway, I haven't watched the video yet, but removing the drive plate using the collet is in my opinion preferable if it is not necessary or you just don't want to remove the cylinder for whatever reason (sometimes they are quite stuck, risk of damage to the fins or exhaust port etc).

When you use the collet nut to remove the drive plate, there is no need to try and lock the crankshaft. Actually I have found it better to just let the crank rotate while loosening the collet. Less friction Thumbs Up

When putting things back together, I have found it the easiest to use a sacrificial propeller to stop the drive plate (and crank) from rotating as you tighten the screw or preferably "a nut on a stud" to drive the drive plate on.

Two Cents

**Cribbs74** Tue Jul 30, 2019 1:44 am

I probably should have kept my mouth shut. I really do appreciate the video as it helps folks that have never taken apart a TD style engine.

We do all have our way of doing things after all.

Thanks for making the video.

KariFS Tue Jul 30, 2019 2:23 am

Ron, it was not my intention to knock on your insight. After all you are far more experienced with these engines. There are always at least two ways to do a thing Smile

Using the collet to drive the drive plate off is a good way if you just want to replace the carb body, as in many cases you can do it even out on the field and without removing the engine from the airplane.

I also use the screw and hammer method if I do a complete teardown, as I often do to my "new old" engines.

Levent Suberk Tue Jul 30, 2019 5:26 am

Cribbs74 wrote:We do all have our way of doing things after all.

Right. I use a vice and a propeller screw to remove the drive plate.

Levent Suberk Tue Jul 30, 2019 5:27 am

Thanks for video Very Happy

rsv1cox Tue Jul 30, 2019 7:14 am

Yes, toothpicks work well to block the piston. Three to six according to displacement. Used this method for years to block pistons for stuck prop removals etc. No more scarred prop drive's.

How to replace a Cox .010 venturi mount? P7290014

getback Tue Jul 30, 2019 9:41 am

Very Good video with useful info for the younger entusiaste All i would add is to use 91% alcohol instead of 70% , it has lot less water in it and if left too long will make the engine very stiff /tight to turn over till dried out , also the damage to the alum. (( Ask me how i know as they say )) Sad

KariFS Tue Jul 30, 2019 10:42 am

Great tip about the toothpicks! Definitely going to use it.

Yet another way to lock the crankshaft, while the piston and cylinder are off, is to insert a ”U” shapes length of fuel hose into the crankcase while the crank pin is at TDC. When you rotate the crankshaft, the hose gets pinched between the pin and case, stopping the crankshaft from rotating.

Hard to explain... I had a picture, maybe even posted it here but can’t find it right now.

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How to replace a Cox .010 venturi mount?

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