Author Topic: 1968 Z28 piston  (Read 1497 times)

Ramjett54

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1968 Z28 piston
« on: December 09, 2011, 08:40:01 PM »
What was the GM part number for the 68 z28 piston?
where was it stamped on the piston?

1968 Z28

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Re: 1968 Z28 piston
« Reply #1 on: December 09, 2011, 09:06:43 PM »
There were two different design pistons used in the 1968 302.  The first design was a carryover from 1967 and had a part #3927177.  Sometime in production they started using a second design piston and it had the part #3946876.  My 1968 07C Z28 had the second design piston.  I have never seen a part number stamped on the piston.  There was a very marked difference in the design of the piston top on the two pistons.  The early piston looked identical to the earlier 327 HP piston.  The later piston looked like the 1969 design....BTW the late 1968 and 1969 pistons had the same part number.

One other detail....everything I have seen written about the second design piston states that it is a floating pin piston.  But...when I tore down my original 302 block it did indeed have the late floating pin piston but the pins were pressed into the rods.  Don't know for sure, but maybe they ran out of the "Pink" floating rods and had to use some "Pink" pressed pin rods when my engine was assembled.  It was assemble on June 19, 1968.
Jerry G.

Z28-1968-07C-Norwood
Ermine White, Red Std. Interior
2nd. Owner, 38,000 miles

jdv69z

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Re: 1968 Z28 piston
« Reply #2 on: December 12, 2011, 09:23:19 PM »
I have some original 2nd design 68/69 pistons form my 69 Z. On the bottom side of the piston is the part no. 3927172 which is the raw forging number I believe. Floating pins as well, with grooves machined to hold retainers.

Jimmy V.
Jimmy V.

GaryL

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Re: 1968 Z28 piston
« Reply #3 on: December 24, 2011, 04:07:36 AM »
There were two different design pistons used in the 1968 302.  The first design was a carryover from 1967 and had a part #3927177.  Sometime in production they started using a second design piston and it had the part #3946876.  My 1968 07C Z28 had the second design piston.  I have never seen a part number stamped on the piston.  There was a very marked difference in the design of the piston top on the two pistons.  The early piston looked identical to the earlier 327 HP piston.  The later piston looked like the 1969 design....BTW the late 1968 and 1969 pistons had the same part number.

One other detail....everything I have seen written about the second design piston states that it is a floating pin piston.  But...when I tore down my original 302 block it did indeed have the late floating pin piston but the pins were pressed into the rods.  Don't know for sure, but maybe they ran out of the "Pink" floating rods and had to use some "Pink" pressed pin rods when my engine was assembled.  It was assemble on June 19, 1968.

I'm not sure there has been anything other than a DZ with full floating pin. The pin always floats thru the piston.

Check out JohnZ's post in this thread: http://www.camaros.org/forum/index.php?topic=8943.0
Gary

Lemans Blue X33. DZ, M20, manual steering. Only BU code rear end is original.

1968 Z28

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Re: 1968 Z28 piston
« Reply #4 on: December 24, 2011, 06:57:02 PM »

I'm not sure there has been anything other than a DZ with full floating pin. The pin always floats thru the piston.

Check out JohnZ's post in this thread: http://www.camaros.org/forum/index.php?topic=8943.0
Agreed...the 1969 DZ always used floating pins with pin retainers.  The second design 1968 piston is the same piston as the 1969 DZ piston....floating pin with retainer groove cut, part #3946876.

What I am saying is my 1968 302 had the second design piston (pin holes cut for retainer grooves)  but had the pins pressed into the pink rods (not floated) and no retainers in the piston pin grooves.
Jerry G.

Z28-1968-07C-Norwood
Ermine White, Red Std. Interior
2nd. Owner, 38,000 miles