Enginetech grooved cam bearings (CC412)

[Mikko R]

Hi,

I did some reading and ended up getting cam bearings with grooved first bearing, to be fitted while my block is at machine shop anyway.

I was a bit surprised that there is only one hole in the grooved bearing.
I have seen quite many posts about the location of holes on these forums, so I expected to have two holes in this one as well.

If I understand this correctly, the groove allows oil a passage to the drivers side all the time, so in theory there would be no need for the second hole.
Or am I completely lost here ?
I would also assume the hole should be lined with the passenger side hole in block, to provide oil between camshaft and the bearing ?

In general, the box says these interchange with 1782M, SH-1385S and B-12B, so I belive they are a correct set for 1979 block.


Thanks for your advice again

-Mikko-

 

[earlbrown]

There has to be some sort of way for oil to get from the passenger side galley to the DS galley. That can be done with a grooved block (that your 79 most likely doesn't have), a grooved bearing on the backside, or a cam with a groove in the front journal (the crappiest way to do it). You can also get some fittings and connect the two on the back of the block in place of the pipe plugs.

My method is to take a Dremal tool with a disk shaped stone and make a groove in the block. Then install the oil hole at 4:00 when looking at the front of the block.

 

[Wahoo]

This needs to be done on every 109 block?

 

[RmvBfrFlght]

This needs to be done on every 109 block?

No, the 109 blocks are grooved from the factory. The older 3.8l and all 4.1l blocks need to have the grooved bearing or a groove added to the block.

RemoveBeforeFlight

 

[Wahoo]

No, the 109 blocks are grooved from the factory. The older 3.8l and all 4.1l blocks need to have the grooved bearing or a groove added to the block.

RemoveBeforeFlight

So I dont have to tell my machinist to do anything special for the cam bearings for my 109 block?

 

[RmvBfrFlght]

So I dont have to tell my machinist to do anything special for the cam bearings for my 109 block?

That is correct.

RemoveBeforeFlight

 

[Mikko R]

Thanks Earl!

I assume the 79 block is not grooved, but I had the cam bearings in when I took it to machine shop, so couldn't actually make sure.
I suppose it doesn't harm too much even if there is a groove in the block and I have a grooved bearing.

About the hole position. You point it to 4 o'clock, so towards the driver side hole in the block ?
Is there some specific reason to this position ?
I would have guessed the hole should be towards the passenger side hole in the block.

 

[earlbrown]

The valve springs push the cam down towards the crank, so the load is at 6:00. If you put it at the 8:00 oil hole location your pressurized oil will have to go up and over the cam journal (which is a wider clearance since the cam is pushed down) hemorrhaging oil the whole time. THEN what's left makes it way to the load area where it can do some good.

If you inject oil at the 4:00 position more off it goes under the cam where the actually matters. Plus the oil you don't waste can end up at the lifters, rods, and mains where it needs to be.

The front cam journal needs all the help it can get since it's at the end and not only does it have to contend with valve springs but it also gets loaded from the oil pump. If the cam journal has a groove that costs a lot in square inches of load area much like a groove on the cam side of the bearing. Adding 20/50, a HV pump and the stiffest spring you can find makes it worse.

Ideally you want a smooth solid front cam journal, and a full bearing without a groove. A groove on the backside is OK, but I prefer to groove the block and be done with it.


This science is true with all engines that turn the cam clockwise when looking at it from the front.

 

[Mikko R]

Thank you again!

That was a very good explanation
It's my first engine re-build, so I hope I'm not asking too stupid questions.

-Mikko-