Too many holes in new block

[TxBeaux]

I'm installing a new 506 long block in my 96 truck. In the rear of the valley, under where the fuel filter bolts to the intake manifold there are three bosses. The larger oval shaped boss in the center has two holes that were not in my old block. One is about the diameter of a pencil and beside it sits a quarter sized hole. They are not threaded and appear to go down into the camshaft area. They have small recessed shoulders about an 1/16" wide. There are threaded bosses on each side, about an inch away.

gmctd ...
I'm sure you know what I'm trying to say here.

Can anyone tell me what the deal is and what my options are? Thanks, Jim

[gmctd]

May be the oil supply and return for the center-mounted van and Hummer turbos.

Block-off plate with appropriate o-rings could be the solution - parts guy at Hummer Dealer should know.

Might also double-check that line down the back of the block is only a drain from the open valley

[Dvldog 8793]

Howdy
Sounds like the oil pump drive access hole???
Your old block should have a gear drive plug that goes from the cam to the pump drive. The other small holes are for the hold down fork and possibly the valley drain. Email me picture if you can. I just went through a long block swap so I still have it fresh in my files!
L8r
Conley
the_janssens@earthlink.net

[TxBeaux]

They are the oil supply and drain holes for the turbo on a Hummer. I should have known a Hummer's turbo was rear mounted. I'm going to try freeze plugs first and build a block off plate if I can't find the right size plugs. Thanks, Jim

[TxBeaux]

BTW, GM shows different part numbers for the Van/Hummer engines verus truck engines and doesn't offer a block off plate. Turbo placement and the larger motor mount bolts were the only differences I have found so far. All that's left is bolting up the intake and some off engine stuff.

[Kennedy]

I'd suggest building a block off plate to ensure long service w/o leaks.

If it's a van engine, the intake won't fit either. Bolt angles are different. Truck heads have holes 90

[TxBeaux]

Thanks for jumping in here John. It is a van engine as the bolts are set at the different angle. Will the van intake work and still let me hook up my turbo in the normal position? I've had a block off plate made that will cure the other problem. Thanks, Jim

[Kennedy]

The van intake is entirely goofy. It is 3 pcs. 2 valve cover looking plenums for the heads, and a crossover that the turbo blows directly into...

[TxBeaux]

I spent the day looking for a new set of heads and by the time it was all over, several head dealers had stepped up and offered to trade straight up. Seems like every one has plenty of truck heads but short on the van heads. Still lost all that time and labor.... Don't know whether to get excited about finding the heads or prepare for what's next?????? Thanks to everyone coming to my aid. I'll definately be back because the story never ends........