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Please note: I did not write this up. I typed it up from scanned magazine articles.
Step one: Find some rods.
This example is done on some ford 302 rods. I read one book that said using a press is the only way you can possibly remove gudgeon pines. The book was wrong. If you don't have a press you can still so the job at home quite happily using items from the local hardware store that will cost next to nothing. The lead shot in this story shows what you'll need. The only things you'll have to buy are the nuts, washers and a length of threaded rod.
Photograph 1 shows a close-up of this improvised puller. The nut has had its points rounded off so they won't dig into the piston as it;s wound through. It's not that we wanted to save the original piston, it's just that gouging out the aluminum takes extra effort and, although this method works quite well, it's fairly hard work.
Oil everything that could do with help in the sliding (photographs 2 and 3). Photograph 3 shows the basic setup for the first stage of pulling out the pins. Pass the threaded rod down through the gudgeon pin and fit the rounded nut to the bottom. You'll need to sit washers under the socket so it sits reasonably level. If you don't, the socket will rock sideways and the threaded rod will bend as you apply turning pressure.
On with the job.
When you place the washers, make sure you leave enough room for the pin to be pulled up between them without contact. The bent washer on the ring lands is a result of one gudgeon pin being dragged past without enough room to pass freely. Our concern for this point is not that the washers are worth anything, but that making this mistake will again cost you the extra effort. Oil the bearing surfaces (photograph 3) and start winding (photograph 4).
It takes a fair amount of effort to get the pins moving. After they start to move you'll get them about halfway out and then they'll butt up against the top of the socket. At this stage, you'll have to give the pins more room to rise. Fitting extra sockets around the base of the original is one method. Because the pin is partially out, the extra sockets can be placed directly against its sides (photograph 5).
As we said, removing pins in this way takes a fair bit of work, but if you don't have a press it will save you a few dollars. If you get a particularly difficult pin, you can use two nuts on the rod. Don't allow them to touch each other, just wind them close enough to get a spanner onto both of them. That way, you'll spread the load across twice the number of threads.
Straight and narrow.
Once the pistons have been removed you'll need to examine the rods to see what you have. They must be checked for bend and twist. Professional shops use an expensive fixture for this, but you can achieve acceptable results by eye using the following methods.
Take a short straight edge and sit the big end journal on it as shown (photograph 6).
Take another straight edge and place it in the small end. If you look down in good light and use your eye to align both straight edges, any twist that matters will be apparent.
Support the rod as shown (photograph 7). Place something round in the small end and measure the distance between the lower and upper straight edges.
If there's any difference, you have a bent rod. If any of your rods do show a problem, you might as well try to fix it. The worst you can do is wreck the rod, which won;t matter very much because you can;t fir it if it's bent anyway. The best method of trying to straighten a rod would be to clamp the big end securely in a vice fitted with soft jaws and then to slip a slightly ground-down gudgeon pin into the small end. If you fit a long enough into the gudgeon pin you may be able to straighten it. If not, you;ll just have to go and buy a new rod or two.
Polished act.
These rods are to be beam-polished, lightened and shotpeened. The polishing operations will change the balance of the rods so they'll have to be re-weighed. The items you'll need for this part of the job are show in photograph 8.
These bearings cost $4.50 each and the threaded rod and nuts were about $3. The scales are fairly expensive, so you wouldn't want to buy a set for this job alone. Someone you know must have a set of accurate scales you can use. These were borrowed from a young girl who makes cakes for a hobby. The materials needed for polishing the rods are fairly basic (photograph 9).
A bolt that will fit in the chuck of your drill and perhaps three grades of abrasive belts. It doesn't matter what size or width belts you buy because they can be folded and torn to size quite easily. Buy some of the coarsest grade you can find, some of the finest and some in between. Cut the head off the bolt and cut a slot about 1.5" deep, as shown.
The amount of flashing varies from one set of rods to another. If your set has a lot you can remove the bulk of it using a bench grinder (photograph 10).
Be careful not to take too much material. It's all right to grind across the rod at this stage but don't take anything other then the raised flashing in the centre of the beam (photograph 11).
Protection.
Mount the rod firmly in a vice fitted with aluminum soft jaws (photograph 12).
If you can;t find any aluminum, use a couple of bits of timber, but whatever you do don't clamp the rods without come protection against the steel jaws. Fold and tear of some coarse belt as shown. Fit it into the slot in your modified bolt and wind it around in a direction that will cause it to tighten as the drill rotates. Don;t worry if you put it in backwards -- you'll soon notice your mistake. Start working ( photograph 13).
From now on, all abrasive actions should occur parallel with the beam and never across it. This is because any nicks or scratches will for a point of concentration for operational stresses. Trying to remove such stresses is the whole pint of the exercise. Continue with the coarse belt only until new metal is exposed along the entire beam. Do some work on the flashing around the small end as well.
When you see a uniform layer of new metal, switch to the next finest grade belt and give them a quick going-over. This takes less time then the coarse work. When you've achieved a uniform texture, switch to the finest-grade belt and finish them off (photograph 14).
These are the pistons (photograph 15) and they must be weighed before being fitted to the rods. Write down the weights for each.
You wouldn't expect to see much variation in a set of quality pistons and there weren't with these. They were all within a gram of each other. The scales are only accurate to one gram, so they may be even closer.
Getting the hang of it.
Suspending the bearing hanger from string in this way makes adjustment easy (photograph 16).
The two bearings must be level with each other and the beam of the rod must sit level when you're weighing both the small and big ends. In this shot (photograph 17) the big end looks like it's toughing the bench, but it's not.
If it did, you'd get a false reading. Make sure the the two ball bearings don;t sit in the bearing retainer slots. Use the side of the big-end journal that has only one slot as this will sit between the ball bearings. On the matter of false readings, you must be careful to place the rods in exactly the same place each time. Changing the contact point between the end of the rod and the scales will result in different readings. Practice until you've learned to use the scales properly.
Weigh all the big ends fist and then all the small ends. Write down the results. At ford they number their rods, but if you're using rods that aren't numbered, punch the number of appropriate number of dots into the top of the rod bolts. Putting them anywhere else will mean they'll be polished off during further preparation. If you're going to this much trouble to prepare your rods you'll obviously be replacing the original bolts, anyway, so the marks wont matter.
Find the rod with the heaviest big end. Grind material away from the balance pad until it weighs the same as the lightest rod. Rather then grind flatly, use a curved action as shown (photographs 18 and 19). When you've equalized the same weight of the heaviest big-end with that of the lightest, you'll be able to see how much more you can take from the rod that was heavier. Finish the balance pad down to about 4mm high on the rod that was the heaviest.
Don't lose your balance.
Because you started with the heavier rod you should be able to bring the other rods back to this weight. If you'd removed the balance pad from the lightest rod first, removing enough material from the heavier rods to equalize the weights would weaken them. Equalizing the weights is pretty fiddly. It's a matter of weighing carefully and grinding bit by bit.
When you've done all the big ends, apply the same technique to the small ends. When the weights at all ends are the same, give the rods a final polish with the two finer grade belts. Use the medium first, check the weights and then finish with the fine belt. The balance weights on the rod shown are a bit larger then ideal (photographs 20 and 21). This is because one of the original rods was damaged. This rod is from a different set and it turned out to be quite a bit lighter.
Step one: Find some rods.
This example is done on some ford 302 rods. I read one book that said using a press is the only way you can possibly remove gudgeon pines. The book was wrong. If you don't have a press you can still so the job at home quite happily using items from the local hardware store that will cost next to nothing. The lead shot in this story shows what you'll need. The only things you'll have to buy are the nuts, washers and a length of threaded rod.
Photograph 1 shows a close-up of this improvised puller. The nut has had its points rounded off so they won't dig into the piston as it;s wound through. It's not that we wanted to save the original piston, it's just that gouging out the aluminum takes extra effort and, although this method works quite well, it's fairly hard work.
Oil everything that could do with help in the sliding (photographs 2 and 3). Photograph 3 shows the basic setup for the first stage of pulling out the pins. Pass the threaded rod down through the gudgeon pin and fit the rounded nut to the bottom. You'll need to sit washers under the socket so it sits reasonably level. If you don't, the socket will rock sideways and the threaded rod will bend as you apply turning pressure.
On with the job.
When you place the washers, make sure you leave enough room for the pin to be pulled up between them without contact. The bent washer on the ring lands is a result of one gudgeon pin being dragged past without enough room to pass freely. Our concern for this point is not that the washers are worth anything, but that making this mistake will again cost you the extra effort. Oil the bearing surfaces (photograph 3) and start winding (photograph 4).
It takes a fair amount of effort to get the pins moving. After they start to move you'll get them about halfway out and then they'll butt up against the top of the socket. At this stage, you'll have to give the pins more room to rise. Fitting extra sockets around the base of the original is one method. Because the pin is partially out, the extra sockets can be placed directly against its sides (photograph 5).
As we said, removing pins in this way takes a fair bit of work, but if you don't have a press it will save you a few dollars. If you get a particularly difficult pin, you can use two nuts on the rod. Don't allow them to touch each other, just wind them close enough to get a spanner onto both of them. That way, you'll spread the load across twice the number of threads.
Straight and narrow.
Once the pistons have been removed you'll need to examine the rods to see what you have. They must be checked for bend and twist. Professional shops use an expensive fixture for this, but you can achieve acceptable results by eye using the following methods.
Take a short straight edge and sit the big end journal on it as shown (photograph 6).
Take another straight edge and place it in the small end. If you look down in good light and use your eye to align both straight edges, any twist that matters will be apparent.
Support the rod as shown (photograph 7). Place something round in the small end and measure the distance between the lower and upper straight edges.
If there's any difference, you have a bent rod. If any of your rods do show a problem, you might as well try to fix it. The worst you can do is wreck the rod, which won;t matter very much because you can;t fir it if it's bent anyway. The best method of trying to straighten a rod would be to clamp the big end securely in a vice fitted with soft jaws and then to slip a slightly ground-down gudgeon pin into the small end. If you fit a long enough into the gudgeon pin you may be able to straighten it. If not, you;ll just have to go and buy a new rod or two.
Polished act.
These rods are to be beam-polished, lightened and shotpeened. The polishing operations will change the balance of the rods so they'll have to be re-weighed. The items you'll need for this part of the job are show in photograph 8.
These bearings cost $4.50 each and the threaded rod and nuts were about $3. The scales are fairly expensive, so you wouldn't want to buy a set for this job alone. Someone you know must have a set of accurate scales you can use. These were borrowed from a young girl who makes cakes for a hobby. The materials needed for polishing the rods are fairly basic (photograph 9).
A bolt that will fit in the chuck of your drill and perhaps three grades of abrasive belts. It doesn't matter what size or width belts you buy because they can be folded and torn to size quite easily. Buy some of the coarsest grade you can find, some of the finest and some in between. Cut the head off the bolt and cut a slot about 1.5" deep, as shown.
The amount of flashing varies from one set of rods to another. If your set has a lot you can remove the bulk of it using a bench grinder (photograph 10).
Be careful not to take too much material. It's all right to grind across the rod at this stage but don't take anything other then the raised flashing in the centre of the beam (photograph 11).
Protection.
Mount the rod firmly in a vice fitted with aluminum soft jaws (photograph 12).
If you can;t find any aluminum, use a couple of bits of timber, but whatever you do don't clamp the rods without come protection against the steel jaws. Fold and tear of some coarse belt as shown. Fit it into the slot in your modified bolt and wind it around in a direction that will cause it to tighten as the drill rotates. Don;t worry if you put it in backwards -- you'll soon notice your mistake. Start working ( photograph 13).
From now on, all abrasive actions should occur parallel with the beam and never across it. This is because any nicks or scratches will for a point of concentration for operational stresses. Trying to remove such stresses is the whole pint of the exercise. Continue with the coarse belt only until new metal is exposed along the entire beam. Do some work on the flashing around the small end as well.
When you see a uniform layer of new metal, switch to the next finest grade belt and give them a quick going-over. This takes less time then the coarse work. When you've achieved a uniform texture, switch to the finest-grade belt and finish them off (photograph 14).
These are the pistons (photograph 15) and they must be weighed before being fitted to the rods. Write down the weights for each.
You wouldn't expect to see much variation in a set of quality pistons and there weren't with these. They were all within a gram of each other. The scales are only accurate to one gram, so they may be even closer.
Getting the hang of it.
Suspending the bearing hanger from string in this way makes adjustment easy (photograph 16).
The two bearings must be level with each other and the beam of the rod must sit level when you're weighing both the small and big ends. In this shot (photograph 17) the big end looks like it's toughing the bench, but it's not.
If it did, you'd get a false reading. Make sure the the two ball bearings don;t sit in the bearing retainer slots. Use the side of the big-end journal that has only one slot as this will sit between the ball bearings. On the matter of false readings, you must be careful to place the rods in exactly the same place each time. Changing the contact point between the end of the rod and the scales will result in different readings. Practice until you've learned to use the scales properly.
Weigh all the big ends fist and then all the small ends. Write down the results. At ford they number their rods, but if you're using rods that aren't numbered, punch the number of appropriate number of dots into the top of the rod bolts. Putting them anywhere else will mean they'll be polished off during further preparation. If you're going to this much trouble to prepare your rods you'll obviously be replacing the original bolts, anyway, so the marks wont matter.
Find the rod with the heaviest big end. Grind material away from the balance pad until it weighs the same as the lightest rod. Rather then grind flatly, use a curved action as shown (photographs 18 and 19). When you've equalized the same weight of the heaviest big-end with that of the lightest, you'll be able to see how much more you can take from the rod that was heavier. Finish the balance pad down to about 4mm high on the rod that was the heaviest.
Don't lose your balance.
Because you started with the heavier rod you should be able to bring the other rods back to this weight. If you'd removed the balance pad from the lightest rod first, removing enough material from the heavier rods to equalize the weights would weaken them. Equalizing the weights is pretty fiddly. It's a matter of weighing carefully and grinding bit by bit.
When you've done all the big ends, apply the same technique to the small ends. When the weights at all ends are the same, give the rods a final polish with the two finer grade belts. Use the medium first, check the weights and then finish with the fine belt. The balance weights on the rod shown are a bit larger then ideal (photographs 20 and 21). This is because one of the original rods was damaged. This rod is from a different set and it turned out to be quite a bit lighter.