Compression release

[bertsmobile1]

Watch & listen.
If the compression release is working properly you can hear the compressed air hissing out when you turn the engine by hand.
Also check the height of the valves when closed, they should be the same.
If the head got too hot and the valve guides moved in the head you can have the situation where a valve spring ( usually exhaust ) becomes coil bound and that makes the engine very very hard to turn over cold.
You should have 0.010" to 0.020" between the turns of wire on the springs when the valve fully open.
IF not the guide has shifted.
This will bend pushrods and cause excessive cam wear.

 

[hrdman2luv]

Watch & listen.
If the compression release is working properly you can hear the compressed air hissing out when you turn the engine by hand.
Also check the height of the valves when closed, they should be the same.
If the head got too hot and the valve guides moved in the head you can have the situation where a valve spring ( usually exhaust ) becomes coil bound and that makes the engine very very hard to turn over cold.
You should have 0.010" to 0.020" between the turns of wire on the springs when the valve fully open.
IF not the guide has shifted.
This will bend pushrods and cause excessive cam wear.

I haven't checked the push rods to see if one is bent. Such an easy check. I guess it just didn't cross my mind.

 

[cpurvis]

How can a valve guide that has moved out of position change the amount a valve spring is compressed?

I don't see how that is possible.

 

[ILENGINE]

How can a valve guide that has moved out of position change the amount a valve spring is compressed?

I don't see how that is possible.

When the heads overheat on small engines, the guides move up inside the springs and will hit a point that will prevent the valve from fully opening because the valve retainer hits the guide., causing broken or bent push rods.

 

[cpurvis]

When the heads overheat on small engines, the guides move up inside the springs and will hit a point that will prevent the valve from fully opening because the valve retainer hits the guide., causing broken or bent push rods.

Yes, I understand how that could happen. It can lessen the amount of spring compression, but not increase it. Coil binding is increased spring compression.

 

[bertsmobile1]

When the head gets hot the valve springs pull the valve guide up out of the head.
When the guides get nice and loose the rocker pushes the valve stem down and the guide goes with it .
The valve looses heat through the seat & the guide.
If the guide is not a tight fit in the head the amount of heat the stem looses decreases and the valve sticks in the guide and the guide moves in the head
Engines tend to stop with the inlet compressed or partially compresses so the guide then ends up being too low and when rotated cold the coil binds.
Usually the inlet ends up in and the exhaust ends up out

 

[cpurvis]

I understand the part about valve guides moving. I also understand how the valve spring retainer can hit the guide if the guide moves too far out of the head.

But no matter which way the valve guide moves, it can't cause the valve spring to be compressed too much, aka 'coil binding.' It's just a sleeve that is a slip fit on the valve stem and a press fit into the head. The cam lobe lift and rocker arm ratio are the only two things that determine how much a valve spring is compressed.

Unless I've overlooked something big, that is.

 

[Tinkerer200]

Thanks man. Sounds great.

That only works if you contact me at address posted.

Walt Conner