pistons GM 3959456

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Belgian1979
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pistons GM 3959456

Post by Belgian1979 »

Some of you will have read previous threads. I have taken inspected the parts of the original block in my 79 vette. After removing the carbon on the piston tops, I found partnumber 3959456. These are domed pistons. What was the original intention of these pistons? They seem fairly high CR pistons (in the region of 11/1).
Could these be original L82 type pistons or are we talking about something else?

PS: one of the bores has some traces of rust in them, so I guess I'll be in for a rebore and o/s pistons.
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Re: pistons GM 3959456

Post by Walter R. Malik »

Belgian1979 wrote: Sun May 09, 2021 10:15 am Some of you will have read previous threads. I have taken inspected the parts of the original block in my 79 vette. After removing the carbon on the piston tops, I found partnumber 3959456. These are domed pistons. What was the original intention of these pistons? They seem fairly high CR pistons (in the region of 11/1).
Could these be original L82 type pistons or are we talking about something else?

PS: one of the bores has some traces of rust in them, so I guess I'll be in for a rebore and o/s pistons.
I believe the L82 engines came with forged flat-top pistons. The 350 LT-1 came with forged pistons which had a small dome.
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Belgian1979
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Re: pistons GM 3959456

Post by Belgian1979 »

That's what I found: that these were 70-71 LT1 pistons. Hm, quite strange that these ended up in my engine combined with the 292 heads.
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Re: pistons GM 3959456

Post by Walter R. Malik »

Belgian1979 wrote: Sun May 09, 2021 10:48 am That's what I found: that these were 70-71 LT1 pistons. Hm, quite strange that these ended up in my engine combined with the 292 heads.

Sounds like a dealer had a special engine put together using factory parts for his own car.
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Re: pistons GM 3959456

Post by Tuner »

Belgian1979 wrote: Sun May 09, 2021 10:15 am Some of you will have read previous threads. I have taken inspected the parts of the original block in my 79 vette. After removing the carbon on the piston tops, I found partnumber 3959456. These are domed pistons. What was the original intention of these pistons? They seem fairly high CR pistons (in the region of 11/1).
Could these be original L82 type pistons or are we talking about something else?

PS: one of the bores has some traces of rust in them, so I guess I'll be in for a rebore and o/s pistons.
Polish the bores with the 400 wet-or-dry trick and see if the rust may be no problem. Shine it up, put the old pistons and rings back in it and run it.
Belgian1979
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Re: pistons GM 3959456

Post by Belgian1979 »

Tuner wrote: Sun May 09, 2021 5:27 pm
Belgian1979 wrote: Sun May 09, 2021 10:15 am Some of you will have read previous threads. I have taken inspected the parts of the original block in my 79 vette. After removing the carbon on the piston tops, I found partnumber 3959456. These are domed pistons. What was the original intention of these pistons? They seem fairly high CR pistons (in the region of 11/1).
Could these be original L82 type pistons or are we talking about something else?

PS: one of the bores has some traces of rust in them, so I guess I'll be in for a rebore and o/s pistons.
Polish the bores with the 400 wet-or-dry trick and see if the rust may be no problem. Shine it up, put the old pistons and rings back in it and run it.
The decks also have some surface rust (not sure if it is pitted into the deck? Block sanding it?
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