Help with setting lash.

[JGR32]

I changed our valve springs from Green stripes to yellow. I set the lash at .015 with a little drag and the valves acted like they were preloaded. Loosened them up a little and the motor started up good, went racing. Went to the grid and noticed the motor felt like it had a lot of compression. Tightened them up a little and ran race. Motor ran decent. Get home and motor is cold and it’s hard to start again. I have set the lash several times and it seems after a few revolutions it tightens back up again. I’m lost at this point.

 

[sundog]

Do you re-check the lash after you tighten the jam nut?

 

[JGR32]

Do you re-check the lash after you tighten the jam nut?

Yes.

 

[95 shaw]

Make sure engine is cold when setting. Ie room temp.
Are you setting .015, or .0015?

If trying to set at TDC sometimes can be difficult.

Try setting valves by rotating engine in directions it runs.
Rotate until exhaust just starts to open. Set intake valve.
Rotate on until intake is almost closed.
Set exhaust.
This gets both valves on the base circle of the cam. More consistent
Ymmv.

 

[JGR32]

Make sure engine is cold when setting. Ie room temp.
Are you setting .015, or .0015?

If trying to set at TDC sometimes can be difficult.

Try setting valves by rotating engine in directions it runs.
Rotate until exhaust just starts to open. Set intake valve.
Rotate on until intake is almost closed.
Set exhaust.
This gets both valves on the base circle of the cam. More consistent
Ymmv.

Thank you. I will try again tomorrow. 0015 the smalles feeler gauge I have.

 

[Petty Race Engines]

Thank you. I will try again tomorrow. 0015 the smalles feeler gauge I have.

Set the valves at room temp, feeler gauge not required, pre-load the lash and back off til you can rotate the pushrod with your fingers and lock down and recheck after, may take a few attempts to get it right

 

[1fasttiller]

Zero lash is where I set ours and have the best luck. Trick is to set them cold and make sure you are on the base circle of the cam as mentioned. If not, that will throw you off every time.

 

[flattop1]

Here's another tip .
I just gave blood setting mine .
Anyway when your close , snug it up then turn the adjuster and locknut together .
Then you can get it real close before the final tighning .
I can only roll the push rod when I use both index fingers .

 

[JGR32]

Here's another tip .
I just gave blood setting mine .
Anyway when your close , snug it up then turn the adjuster and locknut together .
Then you can get it real close before the final tighning .
I can only roll the push rod when I use both index fingers .

Got it set now. Engine rolls free. Much blood and cursing was given. Thanks everyone for the advice. I was trying to set at TDC.