At what RPM do these motors valves start to float. I just installed the 3200 spring and in neutral I wanted to to see how high it revved.
It rev's higher (no tac) but it starts to vibrate. Feels kind of like its missing but it might be a balance issue. At what rpm do i need different valve springs?

 

I have the same question and from what I have read if you are going to go to the 4k gov spring you need to upgrade the valve spring so I am guessing that valve float will occur somewhere around 3500 to 4000.

 

I believe they start to float around 3400. Be very careful free-revving without a tach--the 3200 spring will rev well beyond valve float territory. The miss you were hearing (assuming all the pushrods are still intact) is likely due to not enough base timing to burn the fuel above 3k. FWIW, look around at some 1st gen dyno sheets. Even the folks making big power aren't making it over 2700. High revs (relatively speaking) just aren't the nature of the beast.

 

I have the 3200 spring and when I lost my OD and running my usual speeds on the hiway (give or take 85) I was just aproaching valve float, but I would back down. I heard it twice and then ran a conservitive 75-80, that was also due to fuel mileage dropping to 13-15mpg

hope that helps,
Michael

 

What are the signs of valve float?

 

The usual first hints of light contact are "Witness Marks" in the carbon on the tops to the pistons. They often occur well before the driver notices.