How does the timing chain get lub?
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Each head has a hole about the size of a dime to quarter that lets the oil drain from the heads down. If your engine builder is on the ball then he might enlarge the openings by removing some of the casting flash. In addition he might drill a 1/32" or 1/16" hole in the middle oil gallery plug to allow a little more oil to splash onto the chain.
Thread Starter
Instructor
Joined: Jun 2004
Posts: 235
Likes: 0
From: NE
Thanks for the help Marshrat99, but I'm still not understanding how the oil is getting from the heads to the timing chain. Is it dripping down from the big hole above the cam shaft after it has oiled the rockers? It does seem a little lam... like not much oil would get to the chain this way.
I have attached a picture with an arrow to two plugs. These must be the plugs from the oil gallery I'll want to drill with around a .040" hole. Correct? If so, I'll be sure to remove and then drill rather than making a chip mess in my clean block. Drilling one would probably be enough wouldn't it? Do most builders drill them both or just one?
I have attached a picture with an arrow to two plugs. These must be the plugs from the oil gallery I'll want to drill with around a .040" hole. Correct? If so, I'll be sure to remove and then drill rather than making a chip mess in my clean block. Drilling one would probably be enough wouldn't it? Do most builders drill them both or just one?
Burning Brakes
Joined: Aug 2000
Posts: 1,211
Likes: 6
That is the spot they are talking about. Whether you do or not be sure to use a Moroso spacer or Torrington bearing (Crane sells one already in the back of a timing gear set, but there are other options) behind the timing chain to protect the block from damage should the cam walk backwards. Talking from personal experience. Some companies call them block protectors. Most cam companies & Moroso have them. 
Le Mans Master
Joined: Mar 2004
Posts: 7,477
Likes: 1,495
From: Little Rock AR
You can file a small groove from the oil feed hole in the front cam bearing out to the front of the block if you want more lube than the GM engineers designed into the engine.
The cam bearing is pressurised and some oil comes out on the inside of the block and the rest comes out the front side where the cam gear interfaces with the front of the block. The cam gear slings the oil around inside the timing cover and that is where the timing chain gets lube from.
-Mark.
The cam bearing is pressurised and some oil comes out on the inside of the block and the rest comes out the front side where the cam gear interfaces with the front of the block. The cam gear slings the oil around inside the timing cover and that is where the timing chain gets lube from.
-Mark.
