Briggs Valve Float

[Oldsalt]

If you wish to lower the RPM that your valves start to float all ya gotta do is add weight to the valve. In the attached pictures you'll see some strange steel caps that are stock items installed on both valves in my Intec 190. If the design goal was to have a bigger area, than the raw end of the valve, for the rocker to work upon it still can't make any sence. They are MUCH larger in diameter than is necessay for that duty. See the photo with the scale...the shinny spot that shows where the rocker contacts it is only 1/4" in diameter. Is it possible that Briggs, in their infinate wisdom, wish to make the valves float? Is it truely a cheap device to ensure the RPM is limited to a level that will not blow flywheels or rods?

Someone tell me it isn't true! Selling engines designed to float the valves!

In any case, I'm gonna grind them [they are hardened] to about 1/4" diameter to reduce their weight to a minimum.

 

[65ShelbyClone]

Jeez, that's a lash cap and a half! I think if Briggs/Tecumseh wanted the valves to float more easily, it would have been cheaper from a manufacturing standpoint to just use a softer spring.

Here's another idea; you could trim the valve tips to accept Honda caps. Your method doesn't need the valves to come out, though.

 

[Oldsalt]

65 ShelbyClone
My guess is that the designers did indeed wish to have the valves float at a desgned speed but they did not want that single coil spring to get in a hamonic. Used a stronger spring and then defeating it, to some degree, with a weight on the valve. In other words, lowered the natural frequency of valve assembly.

I have several Briggs engines built in the 20s and 30s and of course lots built in the last 50 years. Have always been impressed by the cunning design of may details of all the engines. If I'm correct in the above assumption it is just another interesting feature.

 

[Austin T]

why would you want the valves to float more easily?

 

[5hpminitech]

regalate rpm or if done properly you it is possible to make more power

 

[65ShelbyClone]

You're talking about limited engines like the flatheads where having the valve come higher off the cam in a predictable manner means it's open further and longer than the mandated cam specs would otherwise allow.

For Briggs to do it on a utility Intec, I would suspect liability reduction as the reasoning like Oldsalt said.