Author Topic: 69 Z/28 302 internals  (Read 1051 times)

A.Cassaro

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69 Z/28 302 internals
« on: September 07, 2013, 10:37:53 PM »
Hey everyone looking for some help here. I tor down my 302 today which is the born with engine in my Z. I am wondering if what I have is factory engine internals or not. I was not shocked to see the can has been changed out but I am trying to figure out if everything else is untouched.

The crank is the 1178 crank it measures 2.450 on the mains and 2.0995 on the rods so that is standard...Right?

Bearings were GMM 0400 & I think GMM 0200 I think that's what they read...

Pistons are standard bore but they are all TRW pistons on the inside they all say TRW...Is this right?

I would like to just ring and bearing this engine and keep as much as I can.. Can anyone tell me if this engine would have left the factory this way?

Thanks

Angelo
Rally Green 1969 Z/28 - Under slow resteration
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firstgenaddict

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Re: 69 Z/28 302 internals
« Reply #1 on: September 08, 2013, 12:20:13 AM »
1178 is the factory installed 1969 302 Crank number.
Pistons have been found with TRW or the GM part number, they are full floating pins correct? the pins spin in the rod and the piston, there will be spiral or internal ring retainers on both sides of the piston skirt without which the pin would fall out.
James
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69Z28-RS

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Re: 69 Z/28 302 internals
« Reply #2 on: September 08, 2013, 12:23:16 AM »
I think TRW made the 302 pistons for GM during those years...  sounds like you're factory original...
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A.Cassaro

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Re: 69 Z/28 302 internals
« Reply #3 on: September 08, 2013, 12:29:04 AM »
1178 is the factory installed 1969 302 Crank number.
Pistons have been found with TRW or the GM part number, they are full floating pins correct? the pins spin in the rod and the piston, there will be spiral or internal ring retainers on both sides of the piston skirt without which the pin would fall out.


Yes they are floaters
Rally Green 1969 Z/28 - Under slow resteration
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z28z11

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Re: 69 Z/28 302 internals
« Reply #4 on: September 09, 2013, 01:10:25 PM »

The crank is the 1178 crank it measures 2.450 on the mains and 2.0995 on the rods so that is standard...Right?

Bearings were GMM 0400 & I think GMM 0200 I think that's what they read...

Pistons are standard bore but they are all TRW pistons on the inside they all say TRW...Is this right?

I would like to just ring and bearing this engine and keep as much as I can.. Can anyone tell me if this engine would have left the factory this way?

Thanks

Angelo


Angelo,

Sounds pretty close to original in the bottom end - Pistons were L2210A TRW units from the factory, mains should measure between 2.4479 - 2.4488", rods should be 2.099 - 2.100". Bearings sound like they're marked GM Morraine, which should be stock bearings. I would micropolish the crank, recheck it and bolt it up - the journals are Tufftrided, and wear very slowly compared to a reground crank (that would have the Tufftriding removed by regrinding). My 1178 at 42K miles had no wear, now at 72K shows no wear, even with 12.5:1 piston duty for 30K miles. Watch for piston wear, though - my cylinder bores had little wear (.0002 taper), but my standard pistons were worn in the skirts. I always heard that the blocks were a higher tin/nickel content, but that has been debated here before - better materials and castings than earlier blocks, I suppose.

Regards,
Steve
1968 Z28 M21/U17 BRG/W
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