Cam thrust direction?

69427

69427

The Artist formerly known as Turbo84
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Clinging to my guns and religion in KCMO.
Trying to figure out a couple things prior to putting the new engine together. What's the thrust direction of the cam, specifically the cam gear? I see those thrust buttons installed between the gear and the cover, but I also see writeups showing (aftermarket) roller bearing spacers between the gear and the block. One of these seems unnecessary to me.

Thoughts, opnions?
Thanks.

(Pardon any dumbass questions here, please. It's 12:30 am at the moment, and I'm half asleep typing this.)
 
69427 said:
Trying to figure out a couple things prior to putting the new engine together. What's the thrust direction of the cam, specifically the cam gear? I see those thrust buttons installed between the gear and the cover, but I also see writeups showing (aftermarket) roller bearing spacers between the gear and the block. One of these seems unnecessary to me.

Thoughts, opnions?
Thanks.

(Pardon any dumbass questions here, please. It's 12:30 am at the moment, and I'm half asleep typing this.)
Click to expand...

the button holds the cam from walking forward, the flat bearing saves the block from cam gear wear.....
 
redvetracr said:
the button holds the cam from walking forward, the flat bearing saves the block from cam gear wear.....
Click to expand...
:thumbs:
On a flat tappet cam ,the cam lobes have a angle on them so the lifter drives the cam to the back holding it in place.
A roller cam has level lobes so you need someway of holding the cam in place ;
GM achieved this by fitting a retainer plate to the front of the block which fits a step machined on the front of the OEM cam
 
Exactly, the lobes are ground at a slight angle and the lifter rides off center on the lobes, the downward force of the lifter spinning on the lobe keeps the cam in the block.

This is the OEM GM way in a roller block, cam retainer plate. Just like Fords (they have it on flat tappet cams too!)

24b4069d48d40f.jpg
 
Thanks for the feedback, guys. I'm just trying to figure out if I should get one of those thrust roller bearings that goes between the block and the cam gear to keep from chewing up the block. I don't want any block wear issues, but I also don't want to add any additional items (the bearing) that have a possibility of failure.
 
I machined the cam button on my 502 to get the proper end clearance. I tried the fancy 2pc cover with the clearance adjustment in it and couldn't clear the back of the water pump! Went with an OEM GM steel cover.
 
On a BBC there is an oil gallert that feeds the first cam bearing. You can drill a .040 hole in the face of the block where the cam gear rides into this gallery and get a supply of pressurized oil to the back of the cam gear. This will save you from wearing the front of the block and skip the needle thrust bearing under the cam gear.

The thrust button is a requirement as others pointed out. I welded a washer on the outside of the GM cover because it would flex and the cam could walk forward under power! Make sure you do not drive in the rear cam freeze plug too far and push the cam past flush with the front of the engine.
 
You can do the same on the SBC.

A lot of aftermarket water pumps (the better ones anyway) have a threaded hole where you can thread a bolt or stud in so you can preload the timing cover right where the cam button is touching to keep it from walking.

Just like this here

24b44e55b8979e.jpg
 
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