Hi guys.

I noticed some of my pistons are not completely centered with the connecting rod. I want to try and press the pins a bit further but i dont want to damage the pistons. Has any of you guys have experience pressing these pins? 

The manual shows pictures of a arbor press and some special tools needed to press the pin in or out. I do have a 20 tons press at work. Trying to figure out how to support the piston so that it wont break or gets damaged. Or should i just spend some money and let a professional do it?

I would like to hear your thoughts. 


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Is piston moving freely on the pin/rod? If it is then exactly centered wouldn't matter much. Is not going to cause any vibration or damage on these type of engines, maybe on a 20k+ race engine...

If I would press the pin in a piston I would fabricate a wooden cradle, preferably from a harder kind of wood. Using same diameter in cradle as on piston. That should give sufficient support and avoid any damage. Might be some tools you can buy, checked SummitRacing?

Hi Anders. 

Yes they move freely. I loved to have them completely centered. But if it cant do any harm i will just let them be. Some of them are 2 to 3 mills out of center is that to much?

When i removed the old pistons i did make a cradle like you said. The pistons did not like that and some of them cracked. Do not want that for the new ones. 

Summit sells the motion pro piston pin puller. Worst tool i ever bought. Cheap chinesium. 


I wouldn't cradle the piston. Someone with more experience can chime in, but the piston skirt is not designed for side loading at all. I would drill a hole in a 2X4 piece that is slightly larger than the piston pin and use a deep socket slightly smaller than the pin to press it out and through that hole. The area at the pin is flat and will take the load. Well flat on Chevrolet engines so I'm assuming Cadillac pistons also. If they are round I still would only load the piston at the pin area. 

All that said piston pins from my memory do not have a specification for depth to be pressed. If they came out of a running engine they are totally fine and you are possibly going to cause yourself headaches mucking with them.

Hi Clovis.

Im rebuilding my engine so the pistons and pins are new. I was planning to do something simular of wat you are suggesting. I made a mistake in measurements when connecting the pistons to the rods and 1 rod did not get hot enough so the pin got stuck halfway in the rest is just a bit out of center. Fingers crossed i dont put to much stress on the brittle aluminum. Or it wil be a hard lesson... Measure twice idiot gheheh:).


As I read it it was not to remove the pin, it was to push it a few mm with a 20T Press.

I would still make a cradle so the piston would be secure when applying pressure. The pressure should be directed towards the pin and of course not skirts. On the type of pistons I have seen this would work excellent. But in all honesty I have not seen many aluminum pistons, only steel. Didn't even consider pistons in a 54 year old engine would be aluminum.

I already have a cradle made it out of a synthetic soft block. This cracked the old pistons. Maybe i can modify it so it wont crack the new ones. Yes cadillac was a head of its time with use of materials. Never seen it in any other old engine.

I got some thinking to do. Will let you know how it worked out. 


Take a look at these pistons for the 429 engine. You do not cradle them. All the force is loaded onto the square pad and no where else. Do not cradle them it will distort the piston. 



I made a support out of a socket. Needed to grind two sides a little bit to get it to fit i made a stop into the socket because once the pin moves under pressure it wil go to far trough without the stop. I gave the rod some heat not much to make the pin loose.

Thanks guys. 

You could whip down to local machine shop and have it done with the correct gear.

My 2 cents worth.

I made the correct gear myself it wasnt pretty but it worked excellent. I enjoy doing things like that. Also i went to two machine shops and they didnt have te right tools either.... And they told me: we just get them centered the first time... Yeah yeah i know i made a mistake you dont have to rub it in so hard goshh.


This is very interesting. And even though you make a good description a picture is much more valuable.

If the original post would have had a picture it would have been easier to give an advise. And now with your homemade solution its even more interesting. I would really like to see what you done and how.

If you don't know how to post pictures on this site? There are two ways. Attachment is one way, but the drawback is that everyone has to click on it. When reading on a not-so-smart phone its not easy. If you on the other hand click on the "Image" then the picture is displayed in the post!!!

Like this:


I was so caught up in the process that i forgot to take pictures. I was in my garage today so i made some for you. I used a 24 mm socket and grinded up the sides a little bit. I also got a piece of steel thats fits the inside of the piston pin so it would be centererd correctly under my press. I gave the rod a little heat with a blow torch and gently added pressure until the pin moved. I put a M16 nut in the 24mm socket so the pin wouldend move to far. I made a different suppurt for if things went wrong and i had to push the pin out completely. I made this uit of a 24x27 mm pipe wrench.

I Made these tools just with stuff i had layin around. Like i said, it aint pretty but it works. 




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