Hey guys, I am bulding up my first motor ever, and am a little confused.

I have a brand new GM performance parts block that I bought from summit.
http://store.summitracing.com/partde...3&autoview=sku

I went to install the oil gallery plugs in the front of the motor, but a few of the holes seem way too big. It was my understanding that all three of these holes took a 1/2" drive-in plug that sits just a little below flush. I attached a picture with the hole diameters flagged out. The larger holes do step down to a smaller diameter about 3/4" inches deep. Can someone fill me in on how to properly plug these holes?

Thanks,

Erik

Right: They did in fact change that diameter recently; they USED TO be ½" plugs. You're not the first person to run into this. Small comfort, I'm sure; but at least you're not the only or even the first victim.

If memory serves me right, a 15mm welch plug will work.

Alternatively (and better), is to tap them for 1/8" pipe plugs; get some recessed hex or square drive plugs; and drill them in the center with about a #70 or 75 drill bit. (.020" - .030" or so: very small hole) This will provide a steady small stream of oil to the timing chain.

The casting number for the block is 10243880. Does anyone know where I can find the proper plugs for the three front oil galleries? I don't want to tap the block for threaded plugs since I already have the crank, rods, and pistons installed. (I know, I should have put the plugs in first)

also be careful that what ever plugs are installed, not to be pushed/screwed in so deep, as to block the oil gallery behind it and block the flow.

Out of curiosity, doesn't oil drain out of the front oil galley onto the timing chain? I drilled my pipe plugs with #70 a bit, but now i'm not so sure it's worthwhile, if oil will be draining there anyway.

Very little oil drains out the front there; the engine is tilted rearwards, so it mostly goes that way.

Shouldn't be too hard to find a 15mm plug at the parts store. A ½" should fit the middle one.

Or, check with GM.