[persocon]

just dropped the bare head off at power dynamix yesterday, will be installing springs myself
so the 70s muscle car coworkers telling me I should have optioned for the checking of valve spring tension at install height (in order to dial in equal spring tension across the board) and shim if necessary or machine the spring perch on the head side, is this necessary with modern spring technology? (have bc 80 lb springs and ti retainers)
how important is this longevity-wise, because efficiency wise=just add more boost right?

 

[Hodgdon Extreme]

The valvetrain of OHV/pushrod engines is heavy; you've got all the mass of big valves, the rocker arms, the pushrods, the lifters and the springs themselves. The valve and operating-end of the rocker contribute more to the inertial forces than the rest of the components, but all of them matter.

Valvetrain parts move. Moving mass = inertia. The spring must provide sufficient force to fully counteract the inertia of the valvetrain.

Using 4 little valves instead of 2 big ones decreases inertia. Using direct-acting bucket lifters instead of pushrods and rockers decreases inertia. The 2J lifters are simple and do not incorporate a hydraulic lash-adjusting feature - decreasing inertia.

Thus, an OHC bucket-style valvetrain requires a lot less spring than an OHV design.

I see no benefit to you to have the spring "pressure" (they say pressure, but they mean force) checked or equalized. However, Powerdynamix had damn well better set up your springs to the manufacturers specified installed height.

 

[persocon]

found the tool to check spring force at install height for $75, i'll get it and do it myself.

However, Powerdynamix had damn well better set up your springs to the manufacturers specified installed height.

i didn't option for that springs and retainers are in my hand, i only brought them a bare head to deck, soda clean, valve job, new guides and gsc inconel/stainless valves tip grind to center factory spec. i'm a cheapass and wanted to save on assembly labor

 

[Hodgdon Extreme]

Ensuring the springs are at their correct installed height is not optional. Usually the head shop does it; it involves using a special micrometer between spring seat and valve retainer to take a measurement - then comparing that to the installed height spec - then selecting suitable shims to achieve spec.

Note the shims do not alter valve lash. Only the cam/shim/bucket, valvestem length and valveseat surfaces do.

 

[persocon]

aw crap so i should send them my springs,ret,locks for checking install height. since he knew i'm doing assembly myself, Jeff Tsai didn't mention that was required so he didn't tell me to bring springs

 

[Hodgdon Extreme]

so i should send them my springs,ret,locks for checking install height

I would.

Also, once you get the head back, can you take a bunch of hi-res pics of the port and chamber work that was done?

 

[persocon]

i didn't option for any port and chamber work, only got their "competition valve job", I'm not sure if that constituted any port and chamber work but guess we'll see and i'll get hi-res pics

 

[Hodgdon Extreme]

I must be confused... Somebody recently posted they had Powerdynamix do a CNC port on their 2J cylinder head.

 

[persocon]

yeap that's somebody else he did the whole CNC port job with stock valves. he already got his back and has pics in his thread. Mine's not even started, just dropped it off yesterday
his thread