• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

BN4 Cam Gear Install

Share this page

Csarneson

Csarneson

Jedi Hopeful
Country flag
Offline
This is an embarrassing question to ask. Be gentle...

I've been sidetracked doing body beating and I'm finally finishing up the rebuild of my BN4 engine and am putting the new gear on my reground cam. The bottom of the engine is already closed up. I suddenly realized that the cam is able to slide quite far into the block and getting the gear on far enough on to the end of the cam to get to the threads isn't easy. Did I miss something on the far (back end) end of the cam which keeps it from sliding in? I can't see anything in the manual. What holds the cam in position other than the single retaining plate and then the cam gear? I was expecting to tap the gear onto the cam but I can't because the cam slides in too far. I fear I missed something important inside.
 
Don't panic, you didn't forget anything. The thrust plate behind the gear is the only thing that locates the cam - the front shoulder of the front bearing race stops forward movement against the thrust plate and the rear side of the cam gear stops rearward movement against the same thrust plate.

If you don't have the engine rear plate on then you can reach in and stop the rearward movement of the cam with your hand from the rear of the motor. If the rear end plate is on, I'm not sure where it will be best to hold the cam while the gear is pushed on enough the catch some threads with the cam nut - possibly a large screwdriver in a lifter hole? (careful not to scratch a lobe). If you can get the gear on enough to catch threads you will be good (try it without the lock-tab washer to get it at least part way on, then remove nut & install the lock washer). The gear is normally a very light hand press fit on the cam so hopefully won't be too hard to get on enough to get the nut started.

When you do get the gear on don't forget to check the cam end float - should be 0.003 to 0.006. Can't check until the gear is tight on the shaft.

Dave
 
Last edited:
Thank you so much! While I am a pretty handy guy, this is my first attempt at rebuilding an engine. I'd been so careful at each step and it was completely demoralizing when I suddenly thought I had missed something major.
 
DO BE CAREFUL about letting the cam drift in too far, as the #6 exhaust lobe will damage the rearmost bearing.

BTDT

I'd at least temporarily bolt the rear plate on before going any further with the cam gear installation (or maybe just a bar bolted to a couple of strategic holes, so long as it stops the cam).
 
Back
Top