Cam Journal Oil Hole Line-Up for Valve Train Prime. (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Steamer

SILVER Star
Joined
Jul 20, 2009
Threads
54
Messages
2,156
Location
Miami, FL
This subject comes up from time to time, but I do not recall a definitive answer being mentioned as to what engine position will line up the oil holes in the cam journal to let oil pass through and up through the block and to the valve train. It may have been mentioned, and I missed it. But anyways, here is an observation I made while I have the head off.

Rotating the crank by hand bit by bit, I finally found it. Pistons 1 & 6 are at bottom dead center. At this position I can turn the pump by hand with a screwdriver and oil gushes out of the block oil hole. Doing it by hand lets me think my pump is decent shape. But even though I have # 1 on bottom dead center, I do not know which stroke I am on. I guess I could drop the push rods back in and figure it out, but they are sorted and packed away for now. I marked the flywheel, so I have a 50/50 change of getting lined up again and when it is all back together, I will determine which stroke of #1 BDC is the one & I’ll update here. Just to note, when 1 & 6 are at BDC, 3, 4, 5, & 6 are at even height where 2 & 5 headed down, and even up with 3 & 4 headed up.

Now, if by some chance Toyota did not drill all their cams in the same position and just did it random, this info would be useless. But it may be a starting point for someone searching for it.

CamHoles 01.jpg
 
Good information! I went thu this also Machinist got it there and left for me.If I remember cam is cross drilled at 90 degrees so oil will pass thru every 1/4 turn of cam if thats the case stroke would not matter as long as like you found 1 and 6 bottom dead center.Hopefully all drilled the same.I'm going to write this down in my notes so if any one can add to this information would appreciate it.
 
Yikes! I've been thinking all along that the holes in the cam didn't go all the way through but rather two holes were drilled to the center at right angles where they connect. And the holes only lined up one time for oil to pass. Have I been wrong all this time? I don't recall even looking at them the one time I had mine out. Can someone confirm, is there 2 or 4 holes?
 
Ok I Just did some more testing. I did numerous rotations stopping the #1 piston at TDC and BDC. Each time I stop, I can hand pump the oil out of the oil hole when # 1 piston is at BDC but never at TDC # 1.

So, my conclusion is, that my assumption of two holes at right angles joining in the center but do not going all the way through, is incorrect.

I'm thinking my observations show that two holes must go all the way through but not at right angles. If they both went all the way through at right angles, then the holes would allow flow at every one-fourth rotation of the cam which would be every one-half rotation of the crank. And that would be flow with #1 at both BDC and TDC which is not the case.

So I am thinking that two holes go all the way through but not at right angles. For example, if one hole went from 12 o-clock to 6 o-clock, and the other hole went say, 10 o-clock to 4 o-clock (and the holes in the block match) then you would have proper line up for flow on each one-half rotation of the cam which is one full rotation of the crank. And that would explain why I only get flow on every #1 BDC.

So, I now have a mark on my flywheel for BDC so it will be easy to find in the future. For anyone looking for BDC, I think one way would be turn it to TDC, make a mark on the crank pulley somewhere, where it lines up with anything for reference, then measure with a tape or folding a strip of paper in half, and mark the pulley 180 degrees from the first mark.
Does my logic make sense?
 
I just looked at a 2F camshaft I have, and it has four passages in the third journal.
Ah! Are they at right angles? 90 deg from each other? Or something different?
 
Hole Angle.jpg
 
Excellent! That explains my findings. So, the holes line up for oil flow twice per cam rotation. I think we have a definitive answer.

Number one piston at bottom dead center on either stroke, and the oil holes line up for hand priming the valve train. Thanks fjc-man
 
Excellent! That explains my findings. So, the holes line up for oil flow twice per cam rotation. I think we have a definitive answer.
But, if there are two through and through holes, wouldn't that mean that there are four opportunities per camshaft rotation for oil to move through the bearing?
 
But, if there are two through and through holes, wouldn't that mean that there are four opportunities per camshaft rotation for oil to move through the bearing?
That would be so if the holes were at right angles but as fjc-man pointed out, they are not.
Look at the two red crosses I drew above. the first red cross will be the same with each 1/4 turn. The second will only be the same with each 1/2 turn.
 

Users who are viewing this thread

Back
Top Bottom