Changing pistons, removing wrist pins

[tom3]

Having a real hard time with this. Need to change a couple rods on SB Chev and can't for the life of me get the rods off. Tried serious heat, 12 ton press, BFH on some junker pistons as I need to save the actual pistons I'm going to use. And the design of the SB pistons doesn't leave hardly any solid flat area to push against. Any tricks to this. Hate to just grab a chisel and crack the rod, but that might be next. I see the You tube videos that show how easy it is to put on and off but real life is sure different in my garage.

Help!

 

[Jodi]

Yeah, some of them are really stubborn and will fight you the rest of the way. It's hard to properly support the piston assy. without the actual proper stand / base when using the press? Sometimes a machine shop is the best option for something like this, specially if you're re-using parts.

Have you try the vise and long bolt/spacer trick. I had good luck with this last time I was in a jam, you basically suck the pin out of the rod with the long bolt and spacers while using the vise as support.

 

[tom3]

I'll see what I can rig up. The piston around the pin doesn't have a decent flat area to work from. Might be worth it to take to the shop and hope they'd let me watch?

 

[biker]

Yeah, some of them are really stubborn and will fight you the rest of the way. It's hard to properly support the piston assy. without the actual proper stand / base when using the press? Sometimes a machine shop is the best option for something like this, specially if you're re-using parts.

Have you try the vise and long bolt/spacer trick. I had good luck with this last time I was in a jam, you basically suck the pin out of the rod with the long bolt and spacers while using the vise as support.

Thats good advice. A long, hardened fine thread bolt with the right combo of spacers/washers makes for a good piston pin puller. A piece of black pipe makes great "anvil" for the nut/bolt to apply pressure to the pin with, and draw the pin through. Contour/cut/carve/grind the end of the pipe as needed to fit the contour of the piston around the pin.

I doubt I did a good job articulating the idea, but get bolt through the pin, grind the head as needed to catch the end of the pin, and you will see what needs to be done to make it work. Its messy, but I've only ever needed to do it 3 times in my life. If it was my job, I'd buy the right tool.

 

[biker]

I'll see what I can rig up. The piston around the pin doesn't have a decent flat area to work from. Might be worth it to take to the shop and hope they'd let me watch?

That's why a piece of pipe works well as an anvil. You can shape the end of it to match the pin boss area of the piston and let you put some real torque on it. Lube the threads well.

 

[Jodi]

Thats good advice. A long, hardened fine thread bolt with the right combo of spacers/washers makes for a good piston pin puller. A piece of black pipe makes great "anvil" for the nut/bolt to apply pressure to the pin with, and draw the pin through. Contour/cut/carve/grind the end of the pipe as needed to fit the contour of the piston around the pin.

I doubt I did a good job articulating the idea, but get bolt through the pin, grind the head as needed to catch the end of the pin, and you will see what needs to be done to make it work. Its messy, but I've only ever needed to do it 3 times in my life. If it was my job, I'd buy the right tool.

What I did was made a spacer from thick gauge steel tubing that is longer but slightly smaller in diameter than the wrist pin.
Place that spacer after the Bolt/Washer and get that through the pin, install another washer and nut on the threaded part of the bolt.

Here is where the vise comes in, open the vise jaw slightly wider than the pins diameter then place the piston pin boss right up against the outside edge corner of the vise jaw and tighten the nut on the bolt until the washer is snug on the opposite edge of the vise. Check and see if there is enough clearance between the pin and the vise and then tighten the nut until the spacer pushes the wrist pin out.

Of course it goes without saying, use plenty of lube on the bolts thread.

 

[tom3]

I like that bolt head deal rather than another pipe and all thread/nuts on the push side. The bolt head with some ground off would have a good true surface against the pin. I'll get back into this, really hate to admit defeat. (tore up a lot of stuff due to that)

 

[krabben1]

I just used a vise and a spacer on my 348

,but I was NOT saving pistons,lol.

 

[tom3]

TaDa! It worked really well. Spent an hour or so making the sleeve, found a 1/2 x 8" fine thread bolt with a 3/4 head that worked just right. It came out actually pretty easy and I didn't break anything. Key to this whole engine build was saving the piston. Thanks to all!

 

[tom3]

That 348 piston sure is ugly. Always liked those motors, especially with 3 x 2s. Years ago a buddy had a 55 Chevy with with that motor, real good looking car and that full dressed 348 under the hood, that was a machine!