Quote:
|
The GMC manual lists 76-84 pounds of seat pressure. When I tested mine I got 64 pounds of seat pressure. The Ford spring without spacer got around 40 pounds of seat pressure. The GMC springs didn't make the free length spec either. Looks like they have been getting weaker over the years. Better to replace them now.
I wanted around 100 pounds of seat pressure and less than 280 pounds over the nose. Mike Jones recommended me to not exceed 280 pounds open pressure, otherwise break in springs are needed to break in the camshaft.
A little extra seat pressure should aid in heat transfer and prevent the valve from bouncing on the seat.
Using these springs I designed a spacer and made it out of chromoly steel that I had laying around. Old hydraulic cylinder rod makes for great bar stock. It locates on the valve spring rotator and in combination with the Ford spring gives me 100 pounds of seat pressure and 220 pounds of open pressure. I'm about 1/4" away from coil bind at full lift, so plenty safe.
The spacer in the picture sits cockeyed, was due to a locating bore that was too tight, fixed that later.
To view some links or images in this forum your post count must be 1 or greater. You currently have 0 posts. Maybe you should introduce yourself with a new topic?
|
A few years ago I researched for a replacement valve springs. I ended up using Comp Cams 972-16
To view some links or images in this forum your post count must be 1 or greater. You currently have 0 posts. Maybe you should introduce yourself with a new topic?
(this is for a V8, so I have four spares). I tested the spring and got slightly better than stock specs requirement.