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help on lm7 block

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Old Dec 22, 2013 | 03:44 PM
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Default help on lm7 block

just got the 862 heads off and noticed there was water in a couple of the cylinders and now theres rust... looks like its gonna have to be boared.. where can i get a set of pistons and use stock internals? this was supposed to be a budget build.
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Old Dec 22, 2013 | 04:25 PM
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Originally Posted by rollwithit
just got the 862 heads off and noticed there was water in a couple of the cylinders and now theres rust... looks like its gonna have to be boared.. where can i get a set of pistons and use stock internals? this was supposed to be a budget build.
Had the engine been sitting?

Minor surface rust won't kill an engine, see if you can wipe the rust off with brake cleaner..

And how much water?

Could be when you pulled the heads some of the coolant went in

Post some pics
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Old Dec 22, 2013 | 04:43 PM
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Originally Posted by Burken01
Had the engine been sitting?

Minor surface rust won't kill an engine, see if you can wipe the rust off with brake cleaner..

And how much water?

Could be when you pulled the heads some of the coolant went in

Post some pics
Agreed, and to expand on your original question, look into some "Junkyard Dog" pistons from WISECO. They are forged units and will work with the stock connecting rods .945" wrist pins.
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Old Dec 22, 2013 | 05:05 PM
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Speed Pro has replacement style pistons as well as Mahle and Enginetech.
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Old Dec 22, 2013 | 08:59 PM
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Originally Posted by Burken01
Had the engine been sitting?

Minor surface rust won't kill an engine, see if you can wipe the rust off with brake cleaner..

And how much water?

Could be when you pulled the heads some of the coolant went in

Post some pics
motor has been out in my shop for 3 months.... i bought it off craigslist. No telling how long they had it out. I will try the pic thing
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Old Dec 22, 2013 | 09:37 PM
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Originally Posted by Burken01
Had the engine been sitting?

Minor surface rust won't kill an engine, see if you can wipe the rust off with brake cleaner..

And how much water?

Could be when you pulled the heads some of the coolant went in

Post some pics
tried to clean. sligthly pitted. If i bore to 3.950 any idea what piston i can use with my stock internals?
Attached Thumbnails help on lm7 block-ncm_0012.jpg  
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Old Dec 22, 2013 | 09:41 PM
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Originally Posted by Treyvs
Agreed, and to expand on your original question, look into some "Junkyard Dog" pistons from WISECO. They are forged units and will work with the stock connecting rods .945" wrist pins.
any part #s or links to for pistons? Im new to the ls world, dont know much about them, trying to learn. could i use a ls6 piston with my stock internals?
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Old Dec 22, 2013 | 10:27 PM
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Originally Posted by rollwithit

any part #s or links to for pistons? Im new to the ls world, dont know much about them, trying to learn. could i use a ls6 piston with my stock internals?
Check out Thompson motorsports..

They have killer ls shortblocks

The machine work to bore/hone the cylinders and to find another piston to fit and assembly will be more money than a TMS shortblock
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Look at either Wiseco or Mahle. They should have a piston with the right diameter and compression height that will fit the stock wrist pin. Bore and hone should be around $250 and another $200ish to balance rotating assembly. Before that though I would try a ball hone and see if it cleans up them check your piston to cylinder wall clearance and see if you could still use them being it is a budget build. I was in your shoes a few months ago but just bit the bullet and went ahead and bored it out.
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Old Dec 23, 2013 | 03:48 AM
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guy on youtube lightly sanded the rust down, then just ran it as is. chech it out. look up the squirter 5.3 on youtube. he is on here too.
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Old Dec 24, 2013 | 09:32 AM
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looks like i can ball hone it out! can i use same rings, or should i replace old with new?

?2- if i have to get new ones-what would the ring gap need to be for boost
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