Another 160 problem

Jlovvorn · Post by **Jlovvorn** » Wed Apr 10, 2013 7:19 pm

Sorry to post so much 160 stuff in here, but you all are much more knowledgable than the other forums.

Finished my rebuild, put the cam chain and clip on and now the engine won't turn over.

Well, it will if the valve adjusters are all the way out, but if you screw them in even a little, the whole train stops at the top of the cam lobe on each valve.

It's like the cam is too big (stock) or the springs won't compress (stock reused from before rebuild), or something is blocking the valve from opening in the chamber.

It's so tight, the bolt on the rotor came loose rather than turning the engine over.

My first thought was the pistons are contacting the valves, but it holds up after you pass TDC and both pistons are on the way DOWN.

Anyone have any ideas?

The head is pretty simple, and I assembled the head and valves by the book.

G-Man · Post by **G-Man** » Thu Apr 11, 2013 1:22 am

Sounds like you may have the cam timing wrong.

Does it turn over OK with the cam chain off?

Is this the motor with the 175 pistons?

Have you got a 175 head gasket?

If you have 175 pistons how do they compare with the originals?

Photos, photos, photos.......

G

Jlovvorn · Post by **Jlovvorn** » Thu Apr 11, 2013 7:06 am

Turns freely and smooth as long as valve adjusters are all the way out.

Will take pictures tonight.

Jlovvorn · Post by **Jlovvorn** » Thu Apr 11, 2013 7:20 am

Confirmed with flashlight that pistons are exactly at top when rotor read TDC.

Cam chain seems right from visual inspection from top and with bottom square cover off.

It's on the sprockets, sitting on the large tensioner wheel squarely.

Also confirmed all valves opening and closing as you turn the cam, with the valve lash set to something crazy loose, like a 1/4 inch. Any tighter and it hangs up.

Still baffled.

LOUD MOUSE · Post by **LOUD MOUSE** » Thu Apr 11, 2013 7:57 am

CAM TIMING!. .........lm

Jlovvorn wrote:Confirmed with flashlight that pistons are exactly at top when rotor read TDC.

Cam chain seems right from visual inspection from top and with bottom square cover off.

It's on the sprockets, sitting on the large tensioner wheel squarely.

Also confirmed all valves opening and closing as you turn the cam, with the valve lash set to something crazy loose, like a 1/4 inch. Any tighter and it hangs up.

Still baffled.

Jlovvorn · Post by **Jlovvorn** » Thu Apr 11, 2013 8:04 am

Hey there, I hoped you would chime in!

That was my first thought, but the O mark is dead on high noon, the rotor is at T, and the point cam mark is dead on 6pm. This is exactly how everyone says it should be.

But after my timing failures on the 305, you are right to suspect this :)

Jlovvorn · Post by **Jlovvorn** » Thu Apr 11, 2013 8:07 am

Oh, and when at TDC, I can see visually that that cam lobes are sitting at their lowest point on the rockers, which is where I think they are supposed to be at TDC. If the timing was off, would the cam be positioned such that the rockers are sitting on the low points of the cam lobes?