Wanted: A65 Cylinder 0.015 over

[Mark Julicher]

Re: Wanted: A65 Cylinder 0.015 over

After looking in the parts and overhaul manual, the A-75 and A-65 use three ring pistons right? The piston in your photo looks like an O-200 with the skirt ring configuration. It seems likely to me that the piston skirt is too long and possibly bumping somewhere.

[Edwin Otha]

Re: Wanted: A65 Cylinder 0.015 over

A65 uses a 3 ring piston, p/n 40312 or the cam ground 40731 which uses ther .921 pin. The A75 uses a 3 ring p/n 40577 and a 5 ring 4638 both have the small pins. If the engine is an A75 you need a 40577 piston and a 25127 pin.
Since you have a 4 ring piston installed most likely a p/n 4544, I would weigh the parts and make sure you dont take the engine out of balance. TCM has the current weight limits listed in a S/B.
The piston shown would not be an O200 due to the small pin, change in the compression height and the bore.
EO

[3Dreaming]

Re: Wanted: A65 Cylinder 0.015 over

Robert called it a 4 ring piston, but looking at the picture I count 5. I think this would make it a 4638.

[Edwin Otha]

Re: Wanted: A65 Cylinder 0.015 over

Put in what you want, probably might work.
EO

[Robert Lees]

Re: Wanted: A65 Cylinder 0.015 over

I think 3Dreaming is correct. The piston part number reported as being fitted is 4368.

[astjp2]

Re: Wanted: A65 Cylinder 0.015 over

I have posted the SB on engine balance, its something like 1 or 2 ounces of total mass difference, at 2300 rpm, its not too much of a problem. There is also a difference between the casting numbers and the part numbers of the pistons. If is old piston was good, I would clean, put new rings on and slide it into a new jug. Tim

[astjp2]

Re: Wanted: A65 Cylinder 0.015 over

Speaking of yellow tags, what FAA form is a Yellow tag? I had 4 cylinders that had yellow tags on them and assembled the engine and it seized when it got warmed up. cooled down and it would run. Pulled the jug, tagged .015 and it was only .010. Just because it has a tag does not mean its right. It only means that the cylinder has a piece of paper. TIm

[mikerice]

Re: Wanted: A65 Cylinder 0.015 over

Robert-
Has your IA torn down your engine? Are all pistons the same configuration?

Many A65 engines have been upgraded to A75 over the years by changing pistons and rejetting the carb. A75 can go to 2600rpm while A65 is limited to 2450rpm. The extra 10 HP is only available at max rpm, and the improved pistons were to provide better cooling/lubrication at the 2600rpm redline for the A75. We bought 3 of our cylinders redone at Gibson Aviation in El Reno OK, and now I am wondering if the 4th cylinder we retained had a matching piston/ring setup...

We have an A75 on our BC12D, and went through a mod STC with Terry Bowden years ago to get the engine approved on our BC12D. The Taylorcraft A690 Type Certificate does not allow an A75, and the 10 HP increase is in excess of the 10%HP allowed with a field approval 337. There was also an issue with the correct propeller, as allowed by the Type Certificate.

Just thought I would muddy the water more for you

[Robert Lees]

Re: Wanted: A65 Cylinder 0.015 over

I have posted the SB on engine balance, its something like 1 or 2 ounces of total mass difference, at 2300 rpm, its not too much of a problem. There is also a difference between the casting numbers and the part numbers of the pistons. If is old piston was good, I would clean, put new rings on and slide it into a new jug. Tim

Tim, the A&P has quoted to me that he needs to weigh the pistons for balance purposes. He seems to know what he's talking about.

Rob

[Robert Lees]

Re: Wanted: A65 Cylinder 0.015 over

....Just thought I would muddy the water more for you

Yes. You have. And Yes, all the pistons are the same.

I'm a lowly Taylorcraft owner looking for a cylinder. How hard can that be? I'd find one in a flash here in the UK, but I assume there would be more available in the USA, where all these darn cylinders were made.

Rob

[Guest]

Re: Wanted: A65 Cylinder 0.015 over

Tim, the A&P has quoted to me that he needs to weigh the pistons for balance purposes. He seems to know what he's talking about.

Rob

Yeah but you may have misunderstood, it was to balance his check book!

Dave

[mikerice]

Re: Wanted: A65 Cylinder 0.015 over

We have 3 cylinders and pistons that we removed and replaced with the Gibson Aviation units. We kept all three, because the A65/A75 cylinders are so damn scarce. I was hoping that a FAA Repair Station would come up with a welding procedure to put the cracked cylinders back in service.

Our cylinders should be A75, and they are .015 over. 2 were determined to have cracks, but one was rebuildable (needs hone and valve job). I have to go the hangar to check them out, and see if I can identify the good one out of the three! I can also take a look a the pistons/rings. We are kinda flooding today in Central Texas, so not sure when I will get to the airport. Probably Monday due to schedule.

Mike Rice

[Robert Lees]

Re: Wanted: A65 Cylinder 0.015 over

Yeah but you may have misunderstood, it was to balance his check book!

Dave

I'm sure that's tongue in cheek, and I don't mind. But I have an aeroplane 7000 miles away from me that needs fixing. I've asked him to fix it, and between us we need to find a cylinder.

Rob

[Robert Lees]

Re: Wanted: A65 Cylinder 0.015 over

We have 3 cylinders and pistons that we removed and replaced with the Gibson Aviation units. We kept all three, because the A65/A75 cylinders are so damn scarce. I was hoping that a FAA Repair Station would come up with a welding procedure to put the cracked cylinders back in service.

Our cylinders should be A75, and they are .015 over. 2 were determined to have cracks, but one was rebuildable (needs hone and valve job). I have to go the hangar to check them out, and see if I can identify the good one out of the three! I can also take a look a the pistons/rings. We are kinda flooding today in Central Texas, so not sure when I will get to the airport. Probably Monday due to schedule.

Mike Rice

That would be helpful Mike, thanks.

Are cylinders generally hard to find in the USA?

[mikerice]

Re: Wanted: A65 Cylinder 0.015 over

Hi Robert-
I contacted Harrison Engine Services in Indiana www.harrisonengine.com

He can weld on A65 A75 cylinders. He has one serviceable .015 cylinder that just came available for $450. Talk to Darryl, but you may have to reach him Monday.

Mike Rice