Thread: sbc chev zz4

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Originally Posted by glennsexton

There are several GM part numbers associated with “high performance” connecting rods. The one most people are familiar with is:

14096846 – referred to as “Pink” rods. These are a forged assembly and very desirable. This rod is made from the well-known heavy-duty 1038 steel. It starts as a “select rod” from the forge and then it is Magna-fluxed, shot-peened, heat treated and balanced as a set. GM slapped pink paint on them to differentiate. It’s the common rod in the 350 HO engine and was used in the 1970–1972 LT1, 1970–1974 Z28, and all L82 350s. A heavier-duty version of the same rod is PN 14095071. (It’s possible for early run ZZ4’s to have either of these “Pink” part numbers.)

10108688 - referred to as “Powdered Metal” and are the replacement for the old "pink" rods however; they are not interchangeable and should be used only as a complete set due to the weight difference between these rods and all others.

In 1994, powdered metal (PM) rods emerged with new technology. Some forged rods were still being used, but the PM rods gradually filled the pipeline on LT1 and LT4 engines. The new rods are literally made from sintered “powdered” metal that is pressed and heated to form super-strong, lightweight part. PM rods are really an alloy and sintering is the heating process that bonds the powdered elements together just shy of melting them. The process typically includes a bonding element in the powder mixture to further strengthen the final product. They are a minimum of 2x as strong as the old school “Pink” rods. All engine manufacturers have pretty much converted to PM rods.

As a side note - the PM rods also use a "cracked” or “fractured" cap. The rod and cap are forged as a single piece and the cap is carefully split apart afterward. The idea is to create a very precise fit that is ultimately stronger and better sealing than machined rods and caps.

It goes without saying – really good bolts are standard. ARP for any rebuild..

Regards ,
Glenn

I have two LT1 assemblies in the garage. Should they have PINK's rods? One is a 94 and one a 96 I think? Both are 2bolt mains with alu. heads. I am just sittin on them. I have had them for at least 10 years.

Chances are good that these engines are original since they've have been in your possession - depending on the actual manufacture date, the '94 may still have the 14096846 (pink) rods. The '96 should have the newer (10108688) rods.

I am going to get some numbers and post. I don't like not knowing what I have.

OK both blocks have the 10125327. One block has v0421xpk on the front pad under the head.( I cannot find a number on the other yet. The head number on it is 12551561.)

Just realized I'm hoggin in. Sorry. I'll start my own.

10125327 casting number was used in 1992-96, 350 engines – both 2 and 4 bolt blocks. You already know they are reverse flow cooling.

V0421XPK translates as:

V = Flint assembly plant
04 = April
21 = 21st day
XPK = 1996 “F” body (Camaro/ Firebird), manual transmission, 275 - 325 horsepower (2 bolt is probably the lower figure [“F” body]. Corvette would have been a 4 bolt, 325 horsepower.)

12551561 heads were used on 1996 LT1s. Angle plug aluminum factory head with 2.00 intakes / 1.55 exhaust.

Glen, Is there a reason I dont find a number on the front pad of the other engine?