351 C cracked piston replacement

[CMasters210]

Was just able to pull the motor out a couple weeks ago and tear it apart. Finding only one piston with a fairly small chip gone from the crown. But speed pro doesn't appear to make the one I need anymore. Tried ordering from summit and supposedly they contacted them and got the same thing.

The engine's running speed pro hypers for .060 over bore. #h555cp60

My question is can I run a different brand pistion with almost the same specs? Or is it too much a risk with putting the rotating assembly out of balance? Or am i SOL and just have to get a whole different set?

 

[Jeff73Mach1]

You can probably get away with a comparable piston, but it would be worthwhile to weigh one of the undamaged pistons and adjust the weight of the new one by removing a bit of metal from the inside under the pin bosses or with a lathe from the inside of the skirt. So long as the top of the piston is still at the same height and has the same profile, the engine should not know the difference in brands.

 

[Don C]

My concern with just changing out that one piston is the reason for it failing. Is it due to age or damage? If it is age or damage from pre-detonation (pinging) the rest of the pistons were subject to the same conditions and may also be in danger of failing. Whenever I have to tear an engine down to the extent you will have to I prefer to go through it, new pistons, rings, and bearings.

 

[barnett468]

I just called Jegs and Jegs called Speed Pro while I was on hold and Speed Pro said they have 61 of them on the shelf and that they just sold a set today.

Call Jegs at 1-800-345-4545 and dial extension 641 and talk to Jim.

If you clean and weigh yours first, Speed Pro will send one the same weight or slightly heavier so you can lighten it to the weight you need.

Measure your bores for taper and out of round and measure the piston for wear and check the clearance.

 

[CMasters210]

I just called Jegs and Jegs called Speed Pro while I was on hold and Speed Pro said they have 61 of them on the shelf and that they just sold a set today.

Call Jegs at 1-800-345-4545 and dial extension 641 and talk to Jim.

If you clean and weigh yours first, Speed Pro will send one the same weight or slightly heavier so you can lighten it to the weight you need.

Measure your bores for taper and out of round and measure the piston for wear and check the clearance.

Is that right?? Hot damn, I will give him a call then. I didn't think to try jegs. Just assumed it would lead to the same answer. I wonder why summit ended up telling me that story then. ?

Much appreciated, now I need to go borrow a bore gauge.

 

[CMasters210]

Thought i'd attach a pic in case anyone was curious as to how bad it was.

 

[73pony]

That's bad. I think I would be trying to find what caused that. Did you find the pieces? My guess would be they did some damage as well.

 

[CMasters210]

That's bad. I think I would be trying to find what caused that. Did you find the pieces? My guess would be they did some damage as well.

Actually i couldn't any single piece of metal. I ran my finger nail along the cylinder wall and i can barely feel little scores. It's like the piece that broke off disintegrated. There's not even pits on the head

 

[73pony]

Wow. That is weird. A lot of times the piece that gets broken off ends up stuck in a valve or something.

 

[CMasters210]

Wow. That is weird. A lot of times the piece that gets broken off ends up stuck in a valve or something.

My thoughts exactly, i was was worried that at least a valve was bent or something of that nature.

For all i know maybe the cleveland shot it out the exhaust! Lol jk

 

[mjlan]

I would very curious to figure out what happened as well. You mentioned hypereutectic pistons so my first thought was are your ring gaps kosher?

Let us know what you find!

 

[Don C]

Wow. That is weird. A lot of times the piece that gets broken off ends up stuck in a valve or something.

+1, I saw similar issues a couple of times in the early smog/unleaded gasoline days, usually related to pinging, and at the edge of the piston. The difference was the pounding the top of the piston and the head got from the broken off pieces before they were pulverized and made it into the exhaust.

How many miles are on it, since those pistons were installed? I wonder if it was damaged during installation?