Verifying block year for Head Bolts/Studs

[BR3W CITY]

Since I've got a massive stack 'o' parts in the corner, its about time I get around to ordering some ARP head bolts so I can do the new heads I've had on the bench for almost a year. At some point in 2004, GM switched from a variable length set of bolts, to a single size of head bolt....the problem is knowing which one you need if your ANYWHERE near the switchover point.

My block is a 12553164, which is the standard iron block made from late 98 into 2004. It was from a 2003 fleet van (and vans in general could come with a weird array of last-years and next-years parts)...

The front passenger side of the block has "2162", which if I understand means "February 16 2002" casting date. Is this correct, or did I miss-indentify these numbers?

[boostedc10]

Brew its a 6.0l right? You sure its not 12551364? Never seen a 3164. If its a 1364 the block is an 02-04 and almost definitely has the multiple length head bolts.

If you want to be sure just pull and out head bolt and see if its 6 inches, if it is you know its the multiple length head bolts.

[boostedc10]

I take that back, just looked up the 12551364 and they ran that casting number into 05. Just pull an outer head bolt to be safe, or post a pic of the clock stamp and we can make sure.

[BR3W CITY]

Ya its a 6.0 and the casting is 12551364, I typed wrong. I'm trying to avoid pulling a bolt until the heads actually comes off.

I'll see if I can jam my phone in there to get a pic of the clock.

[boostedc10]

If you are sure it was a stock motor in the Van then it will be the short long setup, regardless of the date on the block. 2004 was the year that it could be either or.

[BR3W CITY]

Motor was a documented fleet van, so I'm pretty confident in the history/mileage on the motor. My code was so rusted up and painted over that I just couldnt' make it out...so I brushed her off with a stainless brush and used some penetrating dye to make it easier to read....




Looks like E162 to me, which would indicate May 16 2002. I can't gain access to where the larger "clock" is usually stamped since my PS/Alt bracket is still in place.

[clinebarger]

Do you have the VIN off the Van? If so, Call your local Chevy dealer, They will be able to give you the PN for what head bolts you need.

[boostedc10]

Typically the date codes start with letters not numbers Brew. If you don't have the vans vin, there should be a partial etched in the block that can tell you the year at least. Like I said before if you are sure it's from an 03 van you can bet it's short/long.

[BR3W CITY]

E isn't a number...right? makes more sense that way.

[boostedc10]

Originally Posted by BR3W CITY

E isn't a number...right? makes more sense that way.

Haha don't know how I missed that reply. Yes that makes more sense.

[crazy longhorn]

BR3W, everything I get on this, is the 2004 -up used the same length bolts...99 -03 had different lengths? For all the confusion, & the bolts are available (a couple days out)....tear it down when ready, & order the parts that you need? also, watch the heads, as far as gaskets, when swapping The shop that did my 5.3 heads , had me confused on the head gaskets. I knew that it was an2000 /5.3, & I knew that it had the releafs in the the decks on the heads, telling me early compo gasket. When I picked up the heads, there was no relief on the decks! They were there....he had to have cut .060-.070 off those heads! A big thanks to the machinist, that was on the ball...the multi layer gaskets do not leak, & the comp ratio is probably a point higher Longhorn

[boostedc10]

Longhorn the questions like this float around because 2004 was a change over year for the bolt sizes. You can have a 2004 motor with either or. I have never seen this for a 2003 so it is safe to say he has a long short motor.

[BR3W CITY]

Holey crap, so Brian Tooley Racing has the head bolts for more than $40 LESS than summit or anywhere else. Not sure if its a typo, but it checked out and order went through (and summit will match it too, but support this dude if thats his legit price).

I've also got his Titanium springs and stuff for valvtrain and its crazy good for the price. Figured I'd let anyone else know if you need to order some bolts, do it NOW...but I can't believe they can undercut summit by $40+

[crazy longhorn]

WOW! Those long/short bolts from ARP, set me back a couple hundo,& change. Longhorn