Hey everybody, I have some questions and want to learn a little bit about this subject.

I had a machine shop put cam bearings in my 84 305 block. If you were to look at the block from the front:

-the first bearing has 2 holes, they are at 4:30 and 7:30 position
-all the rest of the bearings have 1 hole and they are in the 3:00 position

When I flip the motor upside down I can squirt some oil or W/D 40 through the main / crank holes and a little oil will come out of each cam bearing hole that I try.... but most of the oil will run out of the oil pressure sensor hole in the rear of the block.

When I blow compressed air through the main / crank holes some of the air comes out of the connected cam bearing hole and some comes out of the oil pressure sensor hole. The air will cause a tiny bit of W/D 40 to leak out of all the other cam bearing holes if I oil all them up, the one I am blowing on will flow a little more.


1) Is this the way It should flow?
2) Is this the ammount of flow I should have?
3) I thought the cam bearing holes should line up directly with the hole in the main / crank area, what cam bearing position is better? better?
4) Are these cam bearings installed in the correct positions, or will I have to get them repositioned?

I just want to learn and keep her oiled up real good
Thanks

 

The oil system in a SBC is really quite simple.

The pump pumps it up through the rear main cap into a vertical passage with a ½" freeze plug blocking it partway up, then horizontally to the outside of the filter, through the filter to the center, back up and out horizontally to that same vertical passage except just above the ½" plug, then up almost to the driver's side head deck. Then horizontally again to the rear cam bearing journal. There's a groove around that. The horizontal hole continues on through the cam bearing journal, to the distributor hole, and from there to a passage all the way from the front to the rear of the block, right through the middle of the lifter bores. (The distributor body completes the passage.) There's a similar passage on the left side. There's a plug at both the front and the rear of the long passage. There's one other passage through the rear cam bearing journal, it's vertical drilled from above, which intersects the third and most important front-to-rear passage through the block, above the cam (the raised hump on top of the cam that you can see with the intake off). Each cam bearing has a groove about ¼" wide and ¼" deep all the way around it. There's a hole drilled from underneath in the center of each main bearing saddle, through the cam bearing at the groove, all the way up to the front-to-rear passage. Oil is fed from the front-to-rear passage, down to the groove behind the cam bearing, around the back of the bearing (where it feeds the cam bearing through the hole in the bearing), and downwards the rest of the way through the main webbing to the main journal. Then there's a hole in the crank from the main to a rod journal, to lube each rod bearing.

So, you can't really tell much about any of it, from what you've described. It's near impossible to screw any of it up, because it's all drilled into the block. About all that can go wrong is to leave out the ½" plug at the back which will in effect bypass the filter by allowing oil to pass directly from the pump output up to the distribution point; or put the cam bearings in wrong, in such an orientation that there's too much of a gap right where the hole is, which will create a large internal oil leak.

The cam is constantly being pushed downwards by the lifters, and as it rotates clockwise viewed from the front of the motor, it needs for the oil to be fed to it on the driver's side down low. I like to put the cam bearings in with the holes at about 4:30-5:00. 3:00 is a little too far toward that way IMO, but it's not tragicaly wrong like putting them in at 11:00 would be.

 

Thanks,

Thats good news to me.... but I am afraid there is a chance that a small piece of a scotch-brite pad got stuck somewhere in there. I was using the pad and carb cleaner to wipe the surface rust off after washing my block. A tiny piece tore off and I saw it in one of the middle main / crank holes. I thought my cam bearings were lined up even with the main holes and that I had blown / flushed the piece out. I am parinoid now that it could be stuck between the cam bearing and block and will wipe out my crank and main bearing. I was this far done with the motor when I realized the cam bearing holes were not lined up even with the holes in the main and that I could not have blown the piece straight through. Im ready to take the cam bearings out just to make sure