can i use existing pistons?

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buff531

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#1

• Apr 27, 2005

• #1

hey guys below is a pic of a damaged piston i had in my engine. is there ANY way that i can rebuild the engine using this piston if the sides of it are fine??? can i just grind the top of it down a little with a dremmel tool and a fine grit grinding stone???

is this doable?

 

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buff531

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#2

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lets try this again

 

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buff531

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http://forums.stangnet.com/showthread.php?t=537705

thats a link to the thread with the pic.. that is why i cant post it...

 

stang22

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Jan 29, 2003

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#4

• Apr 27, 2005

• #4

buff531 said:

lets try this again

Click to expand...

 

B

buff531

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#5

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thanks for the so informative post stang22... can we please stay on topic here... can anyone please answer this question??

 

stang22

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#6

• Apr 27, 2005

• #6

buff531 said:

thanks for the so informative post stang22... can we please stay on topic here... can anyone please answer this question??

Click to expand...

Sorry I offended you...

Are those stock pistons? Are you planning on any boost or are you currently running any boost? This is strictly my opinion/personal preference, but I wouldn't re-use that piston. I doubt there is any significant way to test the integrity of it after the damage. Maybe with NDI, but that would cost more than the piston itself. I hate to see you clean it back up and then have to take it apart because that piston has a hole in it.

Tim

 

Stang8URMPRT

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Dec 28, 2003

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Apr 27, 2005

#7

• Apr 27, 2005

• #7

It's not worth the risk. Buy some TRW pistons, and rebuild it. Last thing you want to do is start it back up, and it all just fall apart, aka something else is broke, a crack in the cylinder wall from the piece of metal. I had the same thing happen to me, it was a lock washer I dropped down the intake of my 83, bounced around... and bang.. broke the piston, block, and cylinder head. Not worth the risk to me. Tear it all down and rebuild it.

 

Fishhawk

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Apr 27, 2005

#8

• Apr 27, 2005

• #8

Don't even think about it. Rebuild it.

 

MrKwik

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#9

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I wouldn't even consider it. Have you checked to make sure you didnt punch a hole in the block? If your positive that the block is OK and you didnt hurt any of the other pistons, why not just replace the damaged one. Those are stock pistons right? Hell, I got a box of about 3 motors worth of those things in my garage. PM me if you need one. just cover the shipping and its yours. Not worth the risk to try and fix what you got. Since you have it apart, just do it right.

 

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buff531

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#10

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yes iw ill be running boost....

how much would a rebuild kit be then? if i have to buy the pistons it may be worth while to drive my block over to DSS and get a 306 built for $2,000....

Summit sells a re-ring kit that consists of piston rings, a gasket kit, main and rod bearings for like 178.00...

they have a forged kit with all of that plus the addition of the forged piston heads (no connecting rods) for just under $500. im planning on buying a cam with this as well..

you think i can get another stock piston, the rebuild kit, and the cam and be ok?? i really dont have the money for a DSS engine or the kit with the pistons.

 

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buff531

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#11

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and how do i check to see if my block is ok? it was only in the rear most cylinder on the drivers side that is damaged. i dont think it ruined anything else or created any type of hole from what i can see.

 

MrKwik

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#12

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The best way to check the block would probably take the bare block to the machine shop and have it magnaflux'd. But I imagine that you could probably see or feel any damage to the cylinder wall. If the pistons out just feel around and check it real good.

If there isnt too much ridge in the block, you can just hone it and get the rering kit and one fresh piston to replace the damaged one and you would probably be fine. I wouldnt hesitate to use the stock forged pistons. Since you have the thing all apart, it would probably not be a bad idea to have the rotating assembly balanced.

 

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buff531

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#13

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rotating assembly balanced????

what does that mean? and at what time in the assembly process would i need to do this?

 

crazypete

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Oct 22, 2004

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#14

• Apr 27, 2005

• #14

The block is probably fine if it isnt visibly cracked/scratched/gouged. The pistons are soft and the block is hard and the motion was up and down not side to side so the piston and head could be toast with the cylinder walls surviving. natural aspiration, I'd say the block would be ok. Boost.....asking for trouble if your motor isnt up to par.

That piston is going to have tons of high spots and low spots and that cylinder will pre-detonate from the hotspots this creates. No good. At the very least that one will have to go. If you grind it down, you'll have lower compression there and you dont know how strong the remaining material is after such a beating.

For the record, I took 2 of my 302's apart, steel wooled the original pistons to a polished shine, reringed and got perfect emissions, zero oil burn 25 mpg cars that hummed from 2 oil burners. You can reuse pistons on mild engines.

 

MrKwik

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#15

• Apr 27, 2005

• #15

They basically take each piston and rod and make them all weigh the same and they do the same for the crank weights. Makes the motor spin alot smoother especially at higher RPM's. And you pretty much would do it when you took the block to the machine shop before pretty much anything else.