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Since the pan was off I checked the rod bearings, looking good. I got the wrong windage tray, oil sump tube bracket indention in the wrong place
BUT I found a small, partially rounded bit that was obviously broken off something, I suspected piston skirt. Looks like I was right. Does anyone think this is a major problem?
Plan for this motor is strictly drag racing, stock at first, with a carb, maybe a cam later.
Pics. This little bugger. Looks like it came from here.
Yes, stock crank. If I spin it over it doesn't even come close to each other. Curious about how it broke, thinking it was upon install.
Motor is low mileage, I was planning on just running it as is, staying under the stock red line.
Are those pistons really that fragile?
I would be very wary. SOMETHING caused those chunks to break off.
Not welcome words, I know, but I and others here believe a full teardown is warranted here.
Hypereutectic pistons hold up very well in a properly tuned engine. As long as they're not subjected to detonation, they will last a long time. I've used them in 10,000+ rpm, 2hp/cubic inch motorcycle engines, and they last a long time. They aren't forgiving of detonation. If you have heard any spark knock/detonation, that's probably what caused it.
I haven't heard this motor run, supposedly came from a concept vehicle, so very low miles.
I guess I'll pull it to be sure, I just didn't think that little piece from there wouldn't bother anything.
Well, as long as the heads have to come off, I might as well pop a cam in it, right?
It's not the little pieces that are the problem. The reason they came loose IS the problem!
I would be worried. If you're not, hey it's your mess you'll have to deal with.....
OK, I'm not going crazy with this motor, as I said I'm planning to run it with a carburetor and stay under, or not too much over, the stock redline of 6000.
I don't want to change just one piston, but which one do I want? Summit has forged Wiseco Tru Street PTS523AS for about $655 with rings and pins. Do I really need those? A set of Summit hypereutectic are only $165, plus $50 to $140 for rings.
Also stock rods and bolts, or (probably better) go with ARP bolts?
Cam choice? Truck Norris, Stage2, or??? Low mileage used roller lifters and pushrods already in it should be OK, right?
Big thanks to all who share their experience and knowledge.
OK, so I got the Wiseco forged pistons, ARP rod and head bolts, Stage 2, LS Truck Swap Cam, 218/227 112+2, .522/.524 Lift, and valve springs, and new head gaskets.
I did see something about upgrading the rocker bearings, not sure if I need to do that on such a low hour engine.
This is really clean inside, obviously low hours, apparently lots of low rpm time.
Sounds like you're off to a good start. I'd get the rotating assembly balanced and if you can swing the trunnion upgrade do it but it's not something I'd ve overly concerned about them.
OK, so I got the Wiseco forged pistons, ARP rod and head bolts, Stage 2, LS Truck Swap Cam, 218/227 112+2, .522/.524 Lift, and valve springs, and new head gaskets.
I did see something about upgrading the rocker bearings, not sure if I need to do that on such a low hour engine.
This is really clean inside, obviously low hours, apparently lots of low rpm time.
Did you pull the engine down and inspect that cylinder before ordering pistons? If that hole is hurt, you will need to bore and go oversize pistons.
Just want to add that if the bore is OK, why the negative view on replacing 1 piston? Guys have done this for decades. If the bore is good, clearance is on the piston. What I'd be concerned with is what caused this. If this was my engine, and I didn't need forged pistons, I'd buy a new piston, put it together, and check clearances.....
Piston still in motor, I slid it up the bore and see no damage, planning to remove them tomorrow.
My thinking as usually to leave it alone, but if it has to come apart, upgrade it.
Piston still in motor, I slid it up the bore and see no damage, planning to remove them tomorrow.
My thinking as usually to leave it alone, but if it has to come apart, upgrade it.
Forged pistons are stronger, no doubt. However, hypereutectic pistons do have advantages. Strength and detonation resistance are their only drawback, and I get the "while you're in there aspect. I have forged pistons, but only because I was once considering running N2O. I guess it boils down to future plans and strength requirements. Hypereutectic cast pistons are fine in the LS7@the 500chp level......
Last edited by grinder11; Jul 25, 2024 at 10:16 AM.
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Possible issue? 
