Aftyer reading the post that discussed the oil bleeds in front of block, I checked 2 blocks that just came from eng. machine shop, no holes in plugs. I went to the shop and asked why they weren't installed ( got the deer in the headlights look ) they said probably only hotrodders do that. I went to the dealer and ordered 8 plugs, said they had never sold any before now, they orderd them from GM parts, cost me about $50, they do not look like the pics in the post. I checked my eng. books nowhere is it stated about the plugs being needed. The scary part is I have got three guys with LT1's out there without them, I guess i'll lose the labor to install them. Some one who knows please fill me in, I am confused as to the reality of them, are they a must have. I have been building motors 40yr and its an embarrasment not to have known about them in the LT1's. anyone? Danny Mc

 

In my opinion the holes are not needed and they are only there to help with quick air bleed of the oil galley for less valve train noise at engine start up.

They are not there to oil the timing set or water pump gear drive.

Front oil galley plugs with no pin-holes are fine and ok to use with the LT1 and that's what I use for any LT1 that I build, (no matter what timing set is used).

Karl Ellwein
Ellwein Engines

 

One of the things I noticed when I got my new short block from the builder was that the original block, which I still have, has the oil holes and the new short block did not. I figured someone a whole lot smarter than me decided they were necessary, so I drilled them myself.

 

I am sure that they have an engineered purpose. Do you really think that any car maker especially an American car company would spend a few cents more for a process that would not be required. If GM could cut a few cents per car for holes that are not required then they would in a second.

That being said, yes they allow the galleries to be purged of air and the spray is landing on the timing set which is not a bad thing. These holes can be found on most big blocks as well.

On my new motor I removed the plugs and installed thread in plugs that can not pop out and drilled the .030" holes in the outer two.

I would say use the hole.

 

No holes in mine, I'm fine.

 

The holes not only lube the chain they lube the water pump drive gears..
What other SBC has them?
What other SBC has a gear drive water pump?

 

Without the holes, it would take a long time for oil to get on the wp gear teeth as its the only source of oil until the lift valley is full and it it would begin to run out of the drain holes at the front, which would be difficult during accelleration as well. Lots of people are weery of using the gear driven water pump and switch to an electric...of all of the wp gear failures, who knows how many did not have the oil gally holes.