Valve Lash?? Options

[Dave Blackburn]

Ok. So I have my engine out and decided to take one head off and check some things out. Everything looked great!
While the one head was off I checked valve lash on the opposite side. It was about .012".
When I put the other head back on and the valve train back together it went back to around .006".
I adjusted all the valves to the .006" @ TDC, but noticed the valve lash will become larger (up to .009") when I check it at different spots through out the cam rotation.
It seems to be related to the load from the valve springs on the opposite side of the cam from where I am measuring.

Is this normal? Is this because of worn cam bearings? Something else?

Any thoughts would be great.

Thanks, Dave

[Bleyseng]

Ok. So I have my engine out and decided to take one head off and check some things out. Everything looked great!
While the one head was off I checked valve lash on the opposite side. It was about .012".
When I put the other head back on and the valve train back together it went back to around .006".
I adjusted all the valves to the .006" @ TDC, but noticed the valve lash will become larger (up to .009") when I check it at different spots through out the cam rotation.
It seems to be related to the load from the valve springs on the opposite side of the cam from where I am measuring.

Is this normal? Is this because of worn cam bearings? Something else?

Any thoughts would be great.

Thanks, Dave

If you have one head off you can't adjust the valves because the motor will stretch when you put the other head back on.
When you adjust the valves @ TDC you can ONLY measure that one.
You must first set the engine to TDC for number one cylinder, then adjust it to .006. The rotate the engine to number four top of the compression stroke by looking at the dizzy (cap off) and seeing where the rotor lines up with the firing of spark plug number four. Then adjust it and rotate the engine to number three's top of compression stroke the number two's.
At the top of each cylinder's compression stroke is where you adjust the valves for ONLY that cylinder. That's when both intake and exhaust valves are at rest and seated. Other cylinders valves will be opening and closing so you can't check them. You can rotate the motor and check number ones intake valve when it's seated during other parts of it cycle but it will be off clearance. The motor moves when its rotating due to the stresses of the valves opening and closing. So only adjust the valves at the top of each cylinders compression stroke for accuracy.
Geoff

[Dave Blackburn]

Hey, thanks.
All the valves were adjusted from TDC of that cylinder.
My problem is that @ TDC for the cylinder the valve lash is .006, then if I rotate the engine 60-80 degres the lash will go to .009 or something. I do not think this is normal (or is it?).
I am trying to chase down a engine noise that I think is valve train related. Kinda loud tapping. I have heard of a few people with this noise- http://forums.pelicanparts.com/showthread....20&pagenumber=2

Any Ideas??

Thanks, Dave

[Brad Roberts]

Are you sure the engine is at TDC ?? Are you checking at the piston or on the rotor/cap ?? The dizzy will be 27deg. off.


B

[Dave Blackburn]

Checking the engine for TDC, not the dizzy.
There's around 200 degres cam rotation where the cam is flat, right? Well my lash will change (gets larger) as I rotate the engine. I'm pretty sure this is related to the load on the opposite side of the cam from the valve springs??
NORMAL???
Thanks,

[Mark Henry]

It’s normal, You have to much time on your hands! LOL

The cams go bad on the lobes, if your 1800 has good power (for a 1800) the cam is ok. High mileage or poor power engines, even after a head job, means the cam maybe worn out.