a-65 continental Valve question

1600vw

1600vw

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We borescoped my little small bore continental last evening.

On all the exhaust valves on the top right in the center there is a divot. The top of the valve is not flat but has this divot or hole right in the middle where the stem would be on the other end.

All four valves had this making me believe these valves where manufactured like this but I have never seen a valve without a flat top.

Besides finding this we found the cylinders in good shape. the crosshatch pattern on the cylinders have long since gone but the cylinders did not look bad.

We did find a lot of carbon, this engine has been run really rich its complete life. The insides of the exhaust pipes have a dry black carbon in them. We had a hard time keeping the camera out of it.

Speaking of the borescope. I have a friend who works for a big aviation maint. Facility and he borrowed a unit from them. Its a high dollar unit with the camera end being about the size round as a piece of lead in a pencil maybe a little bigger. One can record and take pics with this unit and take measurements. We could not get those functions to work or I would have pics and other info. He is going to see about getting another unit and we will try and get some pics. I will post them once we get them.

Tony
 
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I am having a hard time picturing where you are talking about.

Do you mean: On the top, right in the center?

Top of the stem, valve face or the head side of the valve where it seats at?

1600vw said:
We borescoped my little small bore continental last evening.

On all the exhaust valves on the top right in the center there is a divot. The top of the valve is not flat but has this divot or hole right in the middle where the stem would be on the other end.

All four valves had this making me believe these valves where manufactured like this but I have never seen a valve without a flat top.

Besides finding this we found the cylinders in good shape. the crosshatch pattern on the cylinders have long since gone but the cylinders did not look bad.

We did find a lot of carbon, this engine has been run really rich its complete life. The insides of the exhaust pipes have a dry black carbon in them. We had a hard time keeping the camera out of it.

Speaking of the borescope. I have a friend who works for a big aviation maint. Facility and he borrowed a unit from them. Its a high dollar unit with the camera end being about the size round as a piece of lead in a pencil maybe a little bigger. One can record and take pics with this unit and take measurements. We could not get those functions to work or I would have pics and other info. He is going to see about getting another unit and we will try and get some pics. I will post them once we get them.

Tony
Click to expand...
 
Right on top of the valve square in the middle. All valves I have seen have a flat top. These exhaust valves do not have a flat top, but right in the middle where the stem would be there is a divot.

On one valve this divot was almost full of carbon.

Tony
 
Maybe in 1930 something exhaust valves where made like this and these are original valves. I have no idea just something I have never seen.

Tony
 
As in a tulip valve?
 

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Try the taylorcraft site as many fly the 65 hp cont. And some are expert. Also , I would be sure that the carb. Is gone over carefully by a shop specializing in them . If you have a Stromberg, they can cause problems if float not set right, etc. Bill pancake, in West Virginia is a master on these engines and a great guy to talk to.
 
Like this? Its probably normal, some have that depression out of the box
Ignore the circled area, not my notation.
 

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No this was about the size of the valve stem but on the top like that one. That one is just huge compared to those in my engine.

I have a new marvel carb on my a-65.

This is a new to me engine in an airplane I just purchased. I am going over everything before I fly it.

Tony
 
This is not my valve but looks just like it.

Tony
 

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See how the divot is right in the middle and about the size of the valve stem.

Tony
 
Are you thinking it is not the right valve? Look up the P/N that is supposed to be in there and compare. I would look it up for you but I am a bit short on time.
 
flyingmoose said:
Are you thinking it is not the right valve? Look up the P/N that is supposed to be in there and compare. I would look it up for you but I am a bit short on time.
Click to expand...


I did look for this part and every pic of this part I found did not look like mine. But from other posts this is correct.

I have never seen a valve made like this. Good to know its normal and when I saw all 4 valves looked alike I thought it was normal but I wanted to be 100% sure.

Tony
 
FWIW I don't recall the valves in my A75 looking like that. If they're all like that and the thing runs not sure I would worry too much.
 
jesse said:
FWIW I don't recall the valves in my A75 looking like that. If they're all like that and the thing runs not sure I would worry too much.
Click to expand...

This is a new to me airplane and I am going over everything. Did I run the engine before I purchased it, yes. But now that she is in my hands I am going over this airplane with a fine tooth comb. I am all ready replacing the fuel tank because I did not like what I saw.

Now it's on to the engine. I wanted to do more then a compression test because this test does not tell one squat. So out came a borescope. I liked everything I saw except the divots in the center of these exhaust valves.

Tony
 
1600vw said:
This is a new to me airplane and I am going over everything. Did I run the engine before I purchased it, yes. But now that she is in my hands I am going over this airplane with a fine tooth comb. I am all ready replacing the fuel tank because I did not like what I saw.

Now it's on to the engine. I wanted to do more then a compression test because this test does not tell one squat. So out came a borescope. I liked everything I saw except the divots in the center of these exhaust valves.

Tony
Click to expand...
Interesting how some of these cylinders it's super obvious and some it's much less obvious.
http://www.piperads.com/ads/4-continental-a65a75a80-cylinder-coresj3taylorcraftcubchamppipervintage/

If I were you I would be getting ahold of this guy:
http://www.bowersflybaby.com/tech/fenton.htm
 
jesse said:
Interesting how some of these cylinders it's super obvious and some it's much less obvious.
http://www.piperads.com/ads/4-continental-a65a75a80-cylinder-coresj3taylorcraftcubchamppipervintage/

If I were you I would be getting ahold of this guy:
http://www.bowersflybaby.com/tech/fenton.htm
Click to expand...


Harry Fenton had an EAA webinar I sat in on the day before I did the borescope or on April 30th. It is a multi part webinar and he is doing more. It was on small bore continentals.
I sent Harry an e-mail about this but have not heard back.

Tony
 
jesse said:
Interesting how some of these cylinders it's super obvious and some it's much less obvious.
http://www.piperads.com/ads/4-continental-a65a75a80-cylinder-coresj3taylorcraftcubchamppipervintage/

If I were you I would be getting ahold of this guy:
http://www.bowersflybaby.com/tech/fenton.htm
Click to expand...

Interesting, in the link above, one of the pics looks just like the one that Tony posted. And the exhaust valves in the other pics are all slightly different, with one sans dimple.
 
Both Fenton and Bill pancake are real experts on these engines. Bill has won honors at Oshkosh for his rebuilt aeroncas. Also very hep on small continentals, their carbs, etc. you have not mentioned the airplane type but usually, on that airplanes site, ie: taylorcraft forum, the answers abound. I've owned, over the years , 3 Taylorcrafts, a cub and an 85 hp 7bcm champ. Carbs., regardless of make, Are always a priority and can affect the performance of the engine to a great degree , too lean, too rich etc. float setting, if they are not serviced properly. While many claim they are simple to work on, actually few know how to properly overhaul and set them properly.
 
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I went downstairs and looked at my A-65 junk. That divot in the center of the exhaust valve is normal. Probably part of the manufacturing process.

Dan
 
VanDy said:
I am having a hard time picturing where you are talking about.
Do you mean: On the top, right in the center?
Top of the stem, valve face or the head side of the valve where it seats at?
Click to expand...

Cylinder side of the valve, right where the live center on the lathe that was used to finish up the valve stem held the valve so that it was concentric. Same hole used on the same lathe to make sure that the valve face and seating face was concentric with the stem.

Jim
 
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