1377 valve flat top mod ?

[toddk63]

Can the valve flat top mod be done independently of the pump piston mod, or do the two have to be done together?  The valve mod looks like just grinding a stock part.  The pump piston looks like a whole new custom part.

Thanks,

Todd K.

[Bentong]

Yes, That's what I did with my valve. I just flatten it and lighten up the spring added the flat top piston. With the light valve spring, it makes pumping easier but you have to cock or pull the bolt so the initial air gets in then seals the check valve. I use a hack saw then finished off with a fine tooth file ensuring it mates the flat piston for max performance.

[toddk63]

So if I flatten the valve,  I HAVE to get a flat pump piston?

[Bentong]

Yes, the original piston has a cup seal and plastic that holds it that flex when pump more than 10X and the cup seal will leak out the air you are trying to compress. With the flat top configuration, it's almost no gap between piston and valve face so compressed air goes in the valve not just leaked out. Try here on the flat top piston >  http://accustomparts.com/13xxFlatTopPiston.aspx