I have a set of Vortec heads I'm putting together to put in my '84 T/A with an LT4 hot cam. I bought a spring seat cutter and cut the springs seats to stock depth, narrowing the guide at the same time. The heads are almost ready to assemble.

2 problems.

First, I know the guides need to be trimmed. How much? I hear of Vortec L31 motors having anywhere from .420 lift to .460 lift...How much do you have to trim the guide down? I was thinking either 3/32" or 1/8".

Also, after you trim the guide, what kind of valve seals do you use? I like the Vortec valve seals since I've seen 200k mile Vortec 350's that don't smoke or barely smoke at startup, but since they're made of metal on the outside and rubber on the inside, they don't fit far enough down on the guide after it's trimmed. I did think of trimming the seals though. Either way, I plan on rubber-type seals on all 16 valves. Any ideas? Nobody here has exact specs, and I'm nervous to assemble my heads on a guess, or to take off too much. Anyone here trim their guides and run with no problems? Thanks in advance!

If anyone needs to know, my valve lift at the valve is .525", pushrod length is stock.

 

I would shorten the guide by at least .200".
Then mock up a valve, retainer, locks, and seal.
And check it. You want a minimum .060" extra clearence @ full lift.

There is a cutter you can buy that shortens the guide while maintaining the minor diameter for vortec seals. I believe its it .550"
dia.

Other "positive seals" require a .500" or .530" dia.