I pulled some springs from the 350 engine head.
Is it normal that intake springs are shorter?
Is it normal that the gaskets on exhaust guides are not cupped style but just square section rings?
Is it normal that the outside diameter of the guides are different on intake and exhaust?
Is it normal that I had to hammer the valves (with wood block) to unstuck the locks ?

 

All sounds normal to me. Cup to ring style are fine on a head with good valve guides. If I was replacing the seals on a high miles motor I would use the cups. You can look up part numbers on the valves but the exhaust valve see much hotter temps and is designed different then intake. This includes thicker stems and thicker lower part of the valve.

BTW you can install seals on exhaust valve but they don't do a lot.

 

Thank you for the reply and sorry for delay...
Is it a big deal to replace valve guides? What is involved there?
Stems are the same size on both Valves.
I will order new cup style seals. I see they go in a groove on the valve so means they go up and down with valves. That's it?
What is not really clear on the above picture are the shims that goes under some springs, not every one and some on exhaust and some on intake. You can see them on the picture on the 2 valves on the left of the picture.
Why do they put them under some springs only. Any reason for that? They used different length springs. Valves are 2.020" and 1.50". Looks like they spent time checking things and using different length springs but then why they used some shims only?

 

The exhaust valves should have a rotator on them, and the springs that get them are shorter
Replacing guides is a machine shop operation
You might be able to knurl them yourself

 

What are those rotators?
What do you mean by knurl them myself?

 

A valve rotator
Only the exhaust valves were to have them, but I see motors assembled incorrectly sometimes
Knurling the valve guides just takes a knurler, you use a drill and push it through the guide
The tool repositions some metal, makes an oiling groove, and tightens up the clearance

 

You have no rotators in that picture but two of the springs are made for them
The square o rings are just the factory style valve stem seals
The others are the umbrella style
Some builders prefer those
Forgot to mention, after the knurling procedure, you follow that up with the correct reamer for your valve size, yours should be 11/32

 

The down side to knurling is you should regrind the the seats so you are sure the centerline of the guide is still the centerline of of the valve seat. They may be ok but you would not know for sure until you lap them or vacuum test the head.

 

I don't plan to knurl the guides. They are pretty well tight.
For now I am trying to see if I should use the same set up as it was.

I checked springs for squareness, they are so-so. Lengths are OK, I guess, within .010"
Ordered a spring compressor tester so I can check that their strength is consistent.
I don't plan to change the springs. Engine was running fine. Took it apart to paint and while there I checked that all was correct.
Plus, should I have to replace the springs, I am not sure how I should determine the springs I'll have to order.

From what I can see, if I remove all the shims, I would end up with more consistent spring compression.
I mean the springs lengths are quite close, only the #3 exhaust valve stem protrude longer than the others (valve grind deeper?) and would benefit from a shim whereas it currently do not have any...

 

You need to remove all the springs to replace the stem seals and check the guide clearance
They are cheap, order a set
They might check good and 1 break next week from fatigue
The rotators are quite a bit thicker than the rest of the valve spring retainers
You need to see if you have the rotators and where they are (which valves)
Verify the the location of your rotators and get that correct
Small block Chevs are so easy to remove the valve springs ( lots of room), you can use a cheap spring compressor like this one from Harbor Freight