Stocker P/v clearance

[Robert Simpson]

What p/v clearance in the min you run in a sbc automatic stocker? Also what valve spring pressures do you recommend on the seat and open? Thanks for the help

[Jrh5220]

Originally Posted by Robert Simpson

What p/v clearance in the min you run in a sbc automatic stocker? Also what valve spring pressures do you recommend on the seat and open? Thanks for the help

200 on the seat 425/450 open pv intake .055 ex .065 with the lash.

[Chipper Chapman]

Used run .035/.050 in my 350/255 using a 1409x at 200 on the seat. Reliefs stayed clean but no mechanical touchy feely

[SSDiv6]

There are many variables to take into consideration.

If you degree the cam with no valve train load, you have to compensate the P/V because the cam will retard 2 to 4 degrees when you start up the engine and the reason for running a tighter piston to valve clearance on the intake side. I like to run a tighter clearance on the intake side than on the exhaust side. Also, take into consideration the camshaft profile and lifter type you are running for valve spring pressure. In some profiles, you do not need high spring pressures.

[Alan Roehrich]

Originally Posted by Robert Simpson

What p/v clearance in the min you run in a sbc automatic stocker? Also what valve spring pressures do you recommend on the seat and open? Thanks for the help

You need to talk to your cam grinder about valve spring pressure, there's no way to tell you what you need without knowing the lobe profiles. The aggressive lobes will often want 200# on the seat, and maybe a 500# per inch spring rate.With those pressures, you're going to need 7/16" rocker studs, minimum, and 3/8" x 0.125" wall pushrods. That assumes you have light valvetrain components, such as hollow stem valves and light weight tool steel retainers.



For piston to valve clearance, on the intake side, you can run your total deck clearance, plus 0.010" for a safety margin.On the exhaust side, you'll want 0.065" or more. You want to check that with your as raced valvetrain, and a dial indicator on the retainer.


Also, those numbers assume you have good engine RPM control. And that doesn't mean using a rev limiter to control RPM on the burnout. Ask Pro Stock legend David Reher what he thinks about valvetrain behavior on the rev limiter.

[Robert Simpson]

Thank You all for the helps and suggestions.

[Adger Smith]

https://rehermorrison.com/tech-talk-...g-your-engine/
I think this might be the David Reher comment Alan was talking about.

[sean1970ss]

I always wondered though with P/V what about actual P/V with heat in the motor vs cold I know some guys are are actually running the motors and then degree the cam as an actual hot running motor.

[427FE]

Non coated lifters/cast cam vs coated lifters/billet cam, i was able to go from 180#s to 220-240#

[Jrh5220]

Originally Posted by 427FE

Non coated lifters/cast cam vs coated lifters/billet cam, i was able to go from 180#s to 220-240#

How much didd it help?