: Valve Train Question



codewize
07-15-06, 10:00 PM
Ok I see a lot of discussion regarding sticky lifters. I was always under the impression that OHC engines didn't have lifters but rather the rocker arm rode directly on the cam. Is that not the case?

I know that Honda does some upside down thing in the V-Tech.

eldorado1
07-15-06, 10:36 PM
Are you familiar with the inside of say, a small block chevy?

The lifters ride on the camshaft, and the pushrods sit into the little "cup" on top.

On the 93-99 northstar, the lifters still ride on the camshaft (err... Should I say the camshaft rides on the lifters???) But, the valve stems sit in the little "cups".


On the 2000-2004(?) northstar, it does indeed have rockers. I can't remember exactly how those work. I believe the rockers have a pivot on one end, a roller bearing in the middle that rides on the cam, and the lifter assy on the other end.

codewize
07-16-06, 09:23 AM
Very familiar with small block Chevy. Could build one with my eyes closed, uhh well almost.

So your saying the earlier year N*'s were designed like the V-Tech that I was describing where the lifters are actually on the top of the pushrod. Interesting design I thought.

So then the 2000 + don't have lifters or pushrods, they are designed as I pictured it. Cam rides on one end of the rocker and valve on the other?

Thanks

eldorado1
07-16-06, 12:12 PM
kind of... The early northstars don't have pushrods though. The lifter acts on the valve directly.

For the 2000's, they do have lifters. Otherwise you would have to adjust the valve lash every 10,000 miles.

Ranger
07-16-06, 08:01 PM
http://caddyinfo.ipbhost.com/index.php?act=Attach&type=post&id=2638

unruley247
07-16-06, 08:03 PM
Ranger do you work for GM

Ranger
07-16-06, 08:09 PM
Nah. Got that pic from caddyinfo. It was taken by JimD at the '04 Atlanta auto show. I just remembered seein it before. Infact I had to post and ask if anyone had it or remembered it and Walla.

codewize
07-16-06, 10:57 PM
That's a great picture. I looked all over last night and then my login for media.gm.com wasn't working and that just tweaked me.

Anyway How the frig does that work. Cam ride on a center roller? What's on the opposite side of the valve? Is that a fixed lifter sort of thing? Cam follower huh. wild shit.

Ranger
07-17-06, 11:26 AM
I am not positive, but the way I see it, the rear side is a stationary pivot point. The cam acts on the roller and then pushes on the valve stem. It appears as if there is no lifter involved.

codewize
07-17-06, 11:54 AM
That's what I see also. Thanks so much. You have enlightened me on the N*. Knowledge is power :)


I am not positive, but the way I see it, the rear side is a stationary pivot point. The cam acts on the roller and then pushes on the valve stem. It appears as if there is no lifter involved.

clarkz71
07-17-06, 02:37 PM
When you look at Ranger's picture, on the left is what GM calls a lifter. The top is a ball (and the follower or rocker)has a socket over a hollow cylinder filled with engine oil just like a common lifter. Most foreign cars call them "hydraulic elements", or "zero lash adjusters". And of course the cam rides in the head and pushes down on the roller which pushes down on the valve. I don't know why GM calls them lifters, they don't lift on any of the N*'s.