Valve Stem Seals Differences

[NMNorsse]

If the rocker arms are removed...the valves are closed. Nothin' to push them open with no rockers in place.

Good point.

You could remove the rocker arms first and then pressurize the cylinder and then remove the springs before changing the seals.

 

[Schurkey]

No compressed air? Pop the rocker arms off, rip the spark plug out, feed a bunch of rope into the cylinder LEAVING AT LEAST SIX INCHES OF ROPE HANGING OUT THE PLUG HOLE with the piston near BDC. Run the piston up until it stops, squeezing the rope in the cylinder. The rope keeps the valves from dropping.

Reverse the spin on the crankshaft to lower the piston and pull the rope out when you're done with that cylinder.

 

[GoToGuy]

I was gonna mention that, but thought nah, they'll never believe me. Lol !

 

[rebelyell]

An update.

Groveling through the service manual, I found the valve stem specs, looks like GM parts would need to stretch around the stem (0.3410 > 0.3270), but the FelPro would loosely fit onto the stem (0.3410 < 0.3440). Would the FelPro's even seal?

And I see from the service manual there are no O-rings.

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As stated, there are no O-rings on or around Vortec L30 & L31 Valve Stems.

BUT ... that above spec 1-2 mm or 0.03937" is a HEIGHT dimension .... that specifies how far the seal must be gapped above bevel BEFORE it contacts the large Bevel on guide ... that's means do NOT simply squash seal down as far as you can bang it on there. Keep its bottom edge that distance from guide's bevel. On that manual's page or just after, is a drawing/illustration of same. Many seals come from factory set too high and that's where most of the wild discrepancies about max lift originate.