Small Engines (Lawn Mowers, etc.): Valve Springs 5HP Briggs, little wonder leaf blower, intake spring

Question
Hi,
I have a Little Wonder Leaf Blower - 5H.P. Briggs Engine.

Model 9005PD
Serial #: 8700614
Engine numbers: 130202 - (Type # 1670-01) - (Data Code – 87012907)

Regular maintenance has been done - oil & air filter changes & seasonal cleaning.
From day one, there was a knocking in the engine thus after about 100 hours it has become louder, hence I'm rebuilding the engine & have a question about the Valve Springs.

The book reads: if the Springs do not stand straight - replace them.
My observation is this: they sit in a breather-pocket that has tapered sides - so after 100 hours of use, its pretty certain the Springs would not stand straight?  
1. Should these be replaced - the next ones will only end the same way!
2. Can you tell me the proper height/length of the both the Intake spring & Exhaust springs on this machine? I want to check if they have been depressed. Also, is there some way to test if the Springs still hold their proper strength?

3. My Intake spring is shorter than my Exhaust - is this correct?

4. The Intake Valve/ Tappet clearance is an easy .003, tight .004 & impossible .005 - Should the Valve stem be ground?

Findings when Engine dismantled.
I did find the Rod cap had been scoured badly. Probably loose from the beginning.
Also, the Exhaust Valve was pitted & the shaft had bushing wear. I'm replacing this Valve & Spring.

Thanks, Val


Answer
I'm sure there are ways to check the valve springs but I have never worried about them.  I checked a couple of repair manuals but they didn't provide any specs on the valve springs.

The intake spring is shorter on some engines.  The intake valve will need to be ground or filed so the gap is .005-.007.  Exhaust should be .009-.011.

If the valve guides are wore you may want to replace them with valve guide inserts.  Briggs sell the reamers and drivers to install the guides but they are too expensive to purchase for a one time use.  I would have a shop replace them.  The valve face can be reground instead of replacing the valve but again this requires special tools and it may be cheaper to just replace the valve.

The valve seats should also be re-cut but you can use lapping compound and lap the new valve and seat.  I did this for may years until I finally bought a seat cutter and did not have any problems.  It took more time to lap because I used a course compound and then fine but it worked alright.

I always reused the old valve springs and never had any problems.
Does this help?
Eric