SS valves in 690 heads

[jas63ss]

I have started to build my QB 409 that will be installed ahead of a 4 speed & posi in a
'63 Impala SS convertible. I am getting ready to do the 690 heads and have read how stainless steel valves seem to be recommended by a lot of people on this site because of the unleaded fuel. My question is why are the SS valves easier on the guides etc. than regular valves?
I have been a reader of this awesome site for several years and the info posted is priceless!!! Any help would be great.

Thanks ,Jimmy

 

[Ronnie Russell]

Jimmy, Cant answer with a good technical reason. It just makes sense that todays valves are a better quality than the 60s versions. A new set of stainless valves are a bargain and good insurance. One of the few items for 409s that are reasonalbly priced. I have heard that the stainless valves handle un-leaded fuel better than the old valves. That may or may not be true, but why take a chance on such an expensive engine? Just my opinion........

 

[Fathead Racing]

Stainless valves are the only way to go unless you have hardened seats, the stainless valve will not transfere metal from the exhaust valve to the valve seat. If you are going to replace the valves I would suggest BB Chevy valves for a high performance build as there is a better valve spring selection. I run Ferrera Stainless steel BB Chevy intake and BB Pontiac exhaust valves.

 

[models916]

One piece

SS is one piece of steel, stock is a two piece valve that will come apart after years of banging on the seat and if you add stronger spring pressures it will only hasten the destructive event to follow. I believe SS is also a bit softer than stock valve material and can take a pounding on the seat without the lead cushion. If you are going with new valves, might as well get the full blown high performance cut back valves and get some cheap horsepower. Be sure you get a Serdi 3 or 5 angle valve job.

http://www.carlsspeedshop.com/carlstour/serdi_valve.htm

 

[Skip FIx]

If you are looking at new SS valves look for some longer to use a little taller valve spring for the 690s.

BBC exhausts, and I think BBC intake+0.100 length will give you that extra height.

 

[jas63ss]

Thanks, everyone for the info, after reading all the previous threads on the subject I wanted to go with the SS valves and I needed to know why they seemed to be preferred.

Thanks again and GREAT SITE

Jimmy