910 valve spring installed height

[JD3020]

Whats the minimum installed height that i can safely run with 910's? I did the calculations the other night, and it looks like 1.680" installed height is going to bind, according to the Comps specs and that our 7.3's have .400" lift, which i found on here somewhere.

Reason i ask is i'm shooting for an installed height of 1.750, which would put me at 134lbs of seat pressure. But i'm on the 1st valve, and if i use a .060" shim, i'll be at 1.745".


Is that a safe installed height? And would it be beneficial to go any tighter? Plans are to push this engine with a stock-appearing charger, so i'll likely run into a lot of backpressure and don't want to float an exhaust valve.

 

[powerstrokenstang]

Thats plenty safe as far as bind but if you want that much seat you should prob look into a different spring. A beehive seems to give better pressure and not get excessive. My heads are setup to use a taller spring but i found some beehives to give me about 175 seat with a lil shim but still only 400lbs per inch.

 

[JD3020]

What springs do you have?

And i'm a newb to all this stuff, so what would the advantage of a lightly shimmed beehive spring be, compared to a heavily shimmed 910, both set for 155lbs of seat pressure? Would the beehive give me more seat pressure, with less pressure throughout the valve travel compared to shimmed 910's?


Reason i'm wanting to shim the 910's is that i'm trying to get this thing mildly "built" on a tight budget. I've got the 910's, complete set of shims, and a micrometer here, so i'm wanting to get the most of what i've got. And if all the other valve seats are worn similarly to my first one, i have enough shims to set each one to 1.700" installed, which would put me at 155lbs while still having some clearance until bind. And according to a rough calculation using a valve size of 1.8", that'd give me 86psi before float, which would be more than plenty for my current plans. What that just be too much pressure at full lift for the rockers/pushrods and start breaking stuff?




BTW, i hope i'm not asking too many questions. Been going through hundreds of posts back through 07/08 trying to figure out this valvetrain stuff, and just have a lot of questions that are unanswered.

 

[powerstrokenstang]

I have like $250 including retainers in mine. Mine are pac retainers and scorpian same as pac springs but my spring seat are cut down in the head and i needed to be at 175 at 1.950 installed. But search a lil and you maybe able to find something meant to do what you want w/o stacking shims and such. Theres a lot out there for good prices if you look around and know what you need. I pushed my stock engine hard with unshimmed 910's and wS happy with them but there is def other stuff out there just harder to find.

I should say though if you have the stuff to do it on hand already dont hesitate you will be fine. I was told you only need .050 clearance from bind.

 

[David N]

Why do you want that much seat pressure? Now granted, I just went with the flow... And I just did like most everyone and installed one .030 shim and left it at that.

 

[Ron's Power Stroke]

not sure if you see this post or not..

as the valve (seats) wear...the valve recesses further & further into the head...thereby making the springs' installed height 'taller' than on a fresh head.

OEM spec (off the top of my head) for valve recession in the head is @ .040" +/-

we've had customers supply their own 'rebuilt' heads with new valves and the "works" with the valves recessed closer to .080...

machine shop work (& knowledge), mileage, as well as how clean the air was that went through the engine (dirtier air will increase valve seat wear, further recessing the valve)

as a rough ballpark...trucks with 200k miles on them (typically) will need at least .030 shim to hit our desired installed height for the 910 springs (1.780") which equates to just under 125lbs of seat pressure.

springs installed @ 1.75" would have @ 134lbs of seat pressure.

getting much higher than @ 150lbs of seat pressure can cause the hydraulic lifter spring to collapse and start affecting actual valve lift...without doing things inside the lifter to combat this.

the factory specs are 71-79lbs of seat pressure @ 1.833" installed height, for both I&E valves.

so jusssst swapping in a set of 910's would take you from 71-79lbs to @ 99lbs with no shims.

the valve face diameter is 1.67"...

if you were running (for instance) 45lbs of boost...with stock springs...

you would have ~75lbs of force (45 x 1.67) acting on the valve to open it...without any help from the camshaft...not to mention backpressure acting upon the exh valve (which is typically higher than your boost pressure).

so...a spring is just a spring...sitting on a table..it has zero seat pressure LOL...

installing the spring to do a specific task (high boost high rpm, etc) should be the concern. so I would recommend that you consider your boost & rpm when setting up your seat load.

...and for those that think if some more (pressure) is good...than a "lot" (more) must be better...just keep in mind that the higher the seat load...the more valve wear will occur from the harder 'hit' that the valve & seat absorbs with every opening & closing.

 

[JD3020]

Why do you want that much seat pressure? Now granted, I just went with the flow... And I just did like most everyone and installed one .030 shim and left it at that.

Because i don't want to have to worry about floating valves any with this engine and whatever i end up doing with it in the future. Not planning on going huge, but who knows what'll happen.

Right now, with no shims, i'm sitting at an installed height of 1.805. A .030 shim would put me at 1.775, and without doing the math i'd be around 100lbs of seat pressure

not sure if you see this post or not..

I've seen that post many times, but never paid attention to the lower portion for some reason. So i don't want to go over 150lbs of seat pressure, thats good to know. May just stick around the 1.75 installed height region then, and call it a day.

 

[rustbucket]

You can call summit racings tech line. Tell them want you want out of a spring and they'll set you up. The 910s work but there just not the right spring for 7.3l.