td .051 piston
11-29-2008, 11:13 PM
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td .051 piston
hi im looking for a piston for a td .051 or set piston cylinder will a black widow piston cylinder work on a td .051 i know its going to be hard to find a replacment
11-30-2008, 09:59 AM
#2
RE: td .051 piston
I was alway told that Cox piston and cylinders were sold as a matched set. While I have some doubt that is the complete truth, I think you will have trouble finding just a piston that matches. Cox .051 piston and cylinders have be been made for decades and are by outward appearances, identical. I would worry about finding a piston that is 20 years newer than the cylinder.
If you have to get your Cox running again, try E-Bay.
http://shop.ebay.com/?_from=R40&_trk...All-Categories
Even if you don't buy a "TD" piston and cylinder you should be able to get 'er running again. If it is performance you are worried about, there are better choices today than the TD.
Bill
If you have to get your Cox running again, try E-Bay.
http://shop.ebay.com/?_from=R40&_trk...All-Categories
Even if you don't buy a "TD" piston and cylinder you should be able to get 'er running again. If it is performance you are worried about, there are better choices today than the TD.
Bill
11-30-2008, 01:25 PM
#3
RE: td .051 piston
The .051's are a different bore than the .049 and are indeed sold as sets. The .051 piston has a groove around the bottom to differentiate it from the .049. This was done, as I understand it, so the same free flight ship could be used in both 1/2A and A without trim changes. The power produced by both is supposed to be identical.
George
Edit: Forgot to mention, a piston/cylinder set from another Cox engine WILL fit. A Black Widow or a Sure Start set will get you back in the air. If you use an older one of the "Bee"series, make sure it has two bypass ports or you will see a lot less power.
George
Edit: Forgot to mention, a piston/cylinder set from another Cox engine WILL fit. A Black Widow or a Sure Start set will get you back in the air. If you use an older one of the "Bee"series, make sure it has two bypass ports or you will see a lot less power.
11-30-2008, 01:31 PM
#4
RE: td .051 piston
Hi Gabe,
I have found that the TD .051 piston can be Identified by a etched line around the piston skirt. However, the fit between the piston and the cylinder is critical for good performance. A matched piston/cylinder set would be a better choice if one can be found.
Good luck with your hunt for parts...
Carlos G
I have found that the TD .051 piston can be Identified by a etched line around the piston skirt. However, the fit between the piston and the cylinder is critical for good performance. A matched piston/cylinder set would be a better choice if one can be found.
Good luck with your hunt for parts...
Carlos G
11-30-2008, 04:03 PM
#6
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RE: td .051 piston
ORIGINAL: met3460
Check with ebay id coxmania. I know he used to have them by themselves at a rather reasonable price. He is a good guy to deal with.
Check with ebay id coxmania. I know he used to have them by themselves at a rather reasonable price. He is a good guy to deal with.
Just bought props from him, and would recommend doing business to anyone else needing Cox goodies.
11-30-2008, 04:23 PM
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RE: td .051 piston
Just go to feepay and buy a few Sure Start .049 piston and cylinder sets, then swap out the pistons until you find the best compression, it will still be cheaper than finding a NIP .051 Part if you can find one. Might not be quite as powerful either, but within a 3000 rpm of stock.
11-30-2008, 07:40 PM
#8
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RE: td .051 piston
Look here for a Tee Dee .049 #4 piston cylinder set for C$25.00 as a "buy it now" item from an eBay store run by a guy named Bertie in British Columbia. I assembled a couple of engines with Black Widow cylinder/piston sets and the Killer Bee backplate mounts I bought from him last year. Lots of good Cox NOS parts at reasonalbe prices.
http://stores.ebay.ca/xenalook
http://stores.ebay.ca/xenalook
11-30-2008, 08:15 PM
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RE: td .051 piston
i have a plenty of cox sure starts pistons and cylinder sets and a few black widow that i can use i went to reset the ball socket on the td .051 and the piston would not fit after that i think i hit the piston a little to hard
11-30-2008, 08:37 PM
#10
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RE: td .051 piston
The Black Widow set would be a good choice and if you've got them NIB so much the better. Save the SureStart sets for making instant "beaters" out of worn out Babe Bees.
By the way, just how hard did you hit the reset tool and were you using a 3 lb lead mallet or something?
By the way, just how hard did you hit the reset tool and were you using a 3 lb lead mallet or something?
11-30-2008, 08:45 PM
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RE: td .051 piston
All may not be lost but it's going to require a whole lot of patience to make the deformed piston fit the .051 cylinder again.
I've had this happen to .051 and assorted .049 pistons (due to relative piston hardness I think) even reseting the rod/piston in the most gentle way possible with the Cox tool and anvil.
What I did was wrap some 600 grit emory paper around a tapered dowel ( small end of the taper to the top of the cylinder where the pinch is) and move it in and out with a continual twisting motion. After about 25 strokes in and out, wash the cylinder out and check your piston fit. You aren't removing much cylinder material each time so it might take you 10 or 12 sets of 25 repetitions to make the piston just fit the cylinder. The small tapered end of the dowel won't contact the top cylinder taper so the last few times you may have to make it fit to get the piston to reach top dead center.
If you take your time and sneak up on the final fit you should have a fit pretty close to the original factory specs.
Wash it out carefully and lightly coat the piston/cylinder with Marvel Mystery Oil ( or light lube of your choice) and you should be back in business.
Pay attention and have plenty of patience and you will be happy with the results.
Steve...........
I've had this happen to .051 and assorted .049 pistons (due to relative piston hardness I think) even reseting the rod/piston in the most gentle way possible with the Cox tool and anvil.
What I did was wrap some 600 grit emory paper around a tapered dowel ( small end of the taper to the top of the cylinder where the pinch is) and move it in and out with a continual twisting motion. After about 25 strokes in and out, wash the cylinder out and check your piston fit. You aren't removing much cylinder material each time so it might take you 10 or 12 sets of 25 repetitions to make the piston just fit the cylinder. The small tapered end of the dowel won't contact the top cylinder taper so the last few times you may have to make it fit to get the piston to reach top dead center.
If you take your time and sneak up on the final fit you should have a fit pretty close to the original factory specs.
Wash it out carefully and lightly coat the piston/cylinder with Marvel Mystery Oil ( or light lube of your choice) and you should be back in business.
Pay attention and have plenty of patience and you will be happy with the results.
Steve...........
11-30-2008, 10:22 PM
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RE: td .051 piston
Good Idea....I use a small ball peen hammer and set the Cox anvil on an especially stable, heavy vise to get the full force of the taps to do their work.
I learned the hard way the first few times by putting the Cox tool on a heavy wooden table which has a certain amount of give.
That give makes you have to hit it harder to get results and will guanrantee a deformed piston.
Like my Dad used to say, when working on mechanical things, it's best to have the touch of a jeweler rather than the touch of a blacksmith.
Steve.................
I learned the hard way the first few times by putting the Cox tool on a heavy wooden table which has a certain amount of give.
That give makes you have to hit it harder to get results and will guanrantee a deformed piston.
Like my Dad used to say, when working on mechanical things, it's best to have the touch of a jeweler rather than the touch of a blacksmith.
Steve.................
11-30-2008, 11:42 PM
#14
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RE: td .051 piston
A really slick idea! It's a variation the old hotrodding trick of overboring the cylinders in the block to accept a larger diameter set of pistons to increase the displacement of an engine. Combined with milling the head to increase compression it produced significant power gains.
Thinking about your overbore method a bit, I'd think that it would work even better wet sanding with silicon carbide instead of using emery paper. BTW, did you turn the taper on the dowel yourself or is some manufactured piece I haven't run across?
Thinking about your overbore method a bit, I'd think that it would work even better wet sanding with silicon carbide instead of using emery paper. BTW, did you turn the taper on the dowel yourself or is some manufactured piece I haven't run across?
ORIGINAL: 66Malibu
What I did was wrap some 600 grit emory paper around a tapered dowel ( small end of the taper to the top of the cylinder where the pinch is) and move it in and out with a continual twisting motion. After about 25 strokes in and out, wash the cylinder out and check your piston fit. You aren't removing much cylinder material each time so it might take you 10 or 12 sets of 25 repetitions to make the piston just fit the cylinder. The small tapered end of the dowel won't contact the top cylinder taper so the last few times you may have to make it fit to get the piston to reach top dead center.
If you take your time and sneak up on the final fit you should have a fit pretty close to the original factory specs.
Wash it out carefully and lightly coat the piston/cylinder with Marvel Mystery Oil ( or light lube of your choice) and you should be back in business.
Pay attention and have plenty of patience and you will be happy with the results.
Steve...........
What I did was wrap some 600 grit emory paper around a tapered dowel ( small end of the taper to the top of the cylinder where the pinch is) and move it in and out with a continual twisting motion. After about 25 strokes in and out, wash the cylinder out and check your piston fit. You aren't removing much cylinder material each time so it might take you 10 or 12 sets of 25 repetitions to make the piston just fit the cylinder. The small tapered end of the dowel won't contact the top cylinder taper so the last few times you may have to make it fit to get the piston to reach top dead center.
If you take your time and sneak up on the final fit you should have a fit pretty close to the original factory specs.
Wash it out carefully and lightly coat the piston/cylinder with Marvel Mystery Oil ( or light lube of your choice) and you should be back in business.
Pay attention and have plenty of patience and you will be happy with the results.
Steve...........
12-01-2008, 09:38 AM
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RE: td .051 piston
I thought about the wet sanding method with silicon carbide that you mentioned but realized that fitting the piston to the cylinder was not so much an overboring process but more of a custom honing process. With that in mind, I chose be go much less agressive with the 600 grit emory paper. Although, I don't have any accurate measuring devices to measure the cylinder I.D. or the piston distortion O.D., I believe the distortion is probably only 1/2 to 1 ten thousandths of an inch. The continual twisting motion while making the in and out strokes actually mimics an automotive Sunnen Hone action and it leaves the almost perfect 45 degree hone marks that racing engine builders strive for.
You'll probably laugh, but after trying several different types of dowels wrapped in emory paper that didn't fit, I saw a plastic roller ball writing pen on my desk that looked close. I wrapped it in emory paper and found that the fatness of the pen body was exactly perfect and the tapered top of the pen was exactly right for the TD cylinder pinch at the top of the bore.
I'm sure it sounds goofy, but I saved several really nice piston /cylinder sets that seem to run perfect. Otherwise, they would be packed away in a box somewhere.
Given to the rarity and cost of a new TD.051 piston/cylinder set nowdays, it was worth the try.
Steve.............
You'll probably laugh, but after trying several different types of dowels wrapped in emory paper that didn't fit, I saw a plastic roller ball writing pen on my desk that looked close. I wrapped it in emory paper and found that the fatness of the pen body was exactly perfect and the tapered top of the pen was exactly right for the TD cylinder pinch at the top of the bore.
I'm sure it sounds goofy, but I saved several really nice piston /cylinder sets that seem to run perfect. Otherwise, they would be packed away in a box somewhere.
Given to the rarity and cost of a new TD.051 piston/cylinder set nowdays, it was worth the try.
Steve.............
12-01-2008, 04:15 PM
#16
Senior Member
RE: td .051 piston
Good stuff to read about and store for future use. Thanks!
ORIGINAL: 66Malibu
I thought about the wet sanding method with silicon carbide that you mentioned but realized that fitting the piston to the cylinder was not so much an overboring process but more of a custom honing process. With that in mind, I chose be go much less agressive with the 600 grit emory paper. Although, I don't have any accurate measuring devices to measure the cylinder I.D. or the piston distortion O.D., I believe the distortion is probably only 1/2 to 1 ten thousandths of an inch. The continual twisting motion while making the in and out strokes actually mimics an automotive Sunnen Hone action and it leaves the almost perfect 45 degree hone marks that racing engine builders strive for.
You'll probably laugh, but after trying several different types of dowels wrapped in emory paper that didn't fit, I saw a plastic roller ball writing pen on my desk that looked close. I wrapped it in emory paper and found that the fatness of the pen body was exactly perfect and the tapered top of the pen was exactly right for the TD cylinder pinch at the top of the bore.
I'm sure it sounds goofy, but I saved several really nice piston /cylinder sets that seem to run perfect. Otherwise, they would be packed away in a box somewhere.
Given to the rarity and cost of a new TD.051 piston/cylinder set nowdays, it was worth the try.
Steve.............
I thought about the wet sanding method with silicon carbide that you mentioned but realized that fitting the piston to the cylinder was not so much an overboring process but more of a custom honing process. With that in mind, I chose be go much less agressive with the 600 grit emory paper. Although, I don't have any accurate measuring devices to measure the cylinder I.D. or the piston distortion O.D., I believe the distortion is probably only 1/2 to 1 ten thousandths of an inch. The continual twisting motion while making the in and out strokes actually mimics an automotive Sunnen Hone action and it leaves the almost perfect 45 degree hone marks that racing engine builders strive for.
You'll probably laugh, but after trying several different types of dowels wrapped in emory paper that didn't fit, I saw a plastic roller ball writing pen on my desk that looked close. I wrapped it in emory paper and found that the fatness of the pen body was exactly perfect and the tapered top of the pen was exactly right for the TD cylinder pinch at the top of the bore.
I'm sure it sounds goofy, but I saved several really nice piston /cylinder sets that seem to run perfect. Otherwise, they would be packed away in a box somewhere.
Given to the rarity and cost of a new TD.051 piston/cylinder set nowdays, it was worth the try.
Steve.............
12-02-2008, 10:40 AM
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RE: td .051 piston
I think the best way to get the piston ball socket re-size CORRECT is to "Sneak Up On It", like the old cowboy movies.. Randolph Scott, Audy Murphy, Tom Mix.... oh, I got lost. Sorry. Hit the tool a couple times, rotating the tool 90* each time, and try the fit [grab the piston in one hand and the rod in the other, close your eyes and imagine how far the rod ball moves while you push in and out... tiny, like a piece of paper .002"] then, when it starts getting close, use lighter hits... or go to a smaller hammer. I use a 6 oz. hammer. One tap on each of the four sides of the ball, then check the fit again. Then more taps.... sometimes it takes forty taps to get it almost tight. It's more of an 'art' or a 'feel'. Good luck with the emery paper too. I've done that, very slowly, and it works. [Like honing the brake cylinder on the old 48 Ford...and LOTS of cleaning.] edit... I forgot... some pistons really are softer than others in my opinion.
12-05-2008, 10:02 PM
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RE: td .051 piston
well i got the piston set in the cylinder a lot of work i munted the piston and cylinder assembly on a sure start just to see if its going to work i got it to fire on a prime several times in the house ill try to run it and see
