AMA passenger car specificatins - 1969 z28 "Locked in rod" piston pins

[69er]

69Z28-RS, jdv69z,

I agree post pictures of connecting rods that used full floating piston pins and pressed piston pins that came from the factory.

I believe TRW made the pistons for Chevrolet at that time. And yes, pistons are made to support both types of use, ie - full floating piston pin and pressed piston pin design.

I think that we all benefit to get the facts out as best as we can.

69er

[1968 Z28]

Jerry MacNeish states in his '69 Camaro Z/28 Fact Book,

"Full floating, forged-aluminum pistons were used in the '69 302 engine. 1969 pistons were actually introduced in late-production '68 Z/28s."

Jerry has probably seen the insides of original '69 302 engines more than most people.

Paul

jdv69z,

Thanks for you contribution. But, most/many pistons are manufactured with the grooves
in the piston boss to accommodate retainers.

69er

Huh? OK, it's your turn. Show me evidence of a factory pressed pin piston with machined retainers grooves that were machined and then not used. So Chevrolet would only punch the holes necessary for a specific Camaro firewall, but they machined unnecessary grooves in pistons?  Stick a fork in me, I'm done.

Actually this was done at the factory.....not for 1969 302ci but for the 1968 302ci.  Upon tearing down my original 1968 Z engine (06-19-68 build date) I discovered that my engine had the 1969 version pistons (the ones with the pin lock grooves and straight across valve relief) and the 1968 version pressed pin "PINK" rods. Of course, there were no pin retainers used in the pistons.  Apparently they had already used up all the original design pistons but still had some of the pressed pin "PINK" rods left to use. 

[jdv69z]

Yes, it's the same piston intended for.............., drum roll, floating pins

[BillOhio]

See if this works

[asm69]

BillOhio,

Thanks for you input. Your picture shows the retainer for the piston pin. What really is needed is a nice close up photograph of the small end of the connecting rod, and the whole rod as well. Both
pieces are needed in order to have a full floating piston pin. You have posted a picture that
represents the piston side of the pin being retained. A picture is now needed that shows the connecting rod end. Hopefully showing the machining, and at this point should show wear pattern.

If you can please post the picture of the connecting rod.

69er

[BillOhio]

I didn't find any of the piston off of the rod.

[asm69]

BillOhio,

Are you saying you cannot disassemble the piston from the connecting rod. If this is a full floating piston pin,
all you have to do is remove one retainer. The pin should push out of that side of the piston boss. Sliding right through the connecting rod.

69er

[BillOhio]

I meant I don't have any pictures with the piston off the rod. The engine is back together now.

[jdv69z]

Bill, lots-a-luck! 

[69er]

Bill,
Good picture. But, it doesn't show that the connecting rod is a full floating rod.

[69Z28-RS]

Bill,
Good picture. But, it doesn't show that the connecting rod is a full floating rod.

So what exactly are you looking for in a photo to SHOW that the connecting rod IS manufactured for fully floated pins???   I can probably get such a photo for you if you can state what you are looking for...

[cook_dw]

Problem solved.

[1968RSZ28]

LOL!

Paul

[bertfam]

Sorry Darrell, but that's a reproduction letter. Easy to spot compared to an original, but I won't discuss the differences on a public forum since it would give the fakers too much information.

Ed

[69Z28-RS]

that's a good and very important note there Ed!