When I put the 910 springs in, I didn't measure the spring height or anything, I just took the stock out, and put the 910's in. Should I go back and check the height and add shims where needed or should they be ok? What the best way to measure the spring height?

 

Are you going to be running more than 35-40psi?

 

good question, i would like to know as well. 38R with a stage 1

 

Yes, I haven't really got on it yet, the most boost i've seen so far is 38ish. that on the lowest setting, 3/4 throttle

 

Like to know that to!

 

its not only boost but RPM's as well..its nice to have a balanced out motor..this is what i was told...You should do them but some guy's dont. Nice to get 125 seat pressure up from stock which is 70-75 and that is new. Wonder what it is with a 100K plus on it. Based on Comps spec sheet if you install and shim to spec you will have 125lb seat pressure. Page 3 of 6 the 3rd in from the far right #910

If you have the time and want to do it "the correct way" you should measure each one and use a combo of shims if needed to get them all as close to the same height as possible.

It could take different shim sizes depending on wear. Jegs has a variety pack of harden shims 16 per size 0.015, 0.030, 0.060 Jegs Part #555-20591 That with a valve spring micrometer Jegs # 555-80535 and you can shim them all to the correct height. You will then know what you have. They have a 1.28 max bind height and maybe someone else can given the amount of lift from the stock cam then you could error on the side of slightly lower height and get more seat pressure. Key is you want a safety margin between max bind height and the actual height. something like 1.685-1.700 I seem to recall. But you NEED to Double check that number from someone that knows for sure. That would put it somewhere around 150lb.

 

These are the stock valve spring specs for assembled height and spring pressure (seated and open).

Valve Spring Assembled Height

Intake
44.881 mm
(1.767 in)

Exhaust
46.558 mm
(1.833 in)


Valve Spring Compression Pressure Lbs. @ Specified Height

Intake
32-35 kg@ 46.55 mm (71-79 lbs. @ 1.833 in)
102-112 kg @ 34.35 mm (225-249 lbs. @ 1.352 in)

Exhaust
32-35 kg
@ 46.55 mm (71-79 lbs. @ 1.833 in)
102-112 kg @ 34.35 mm (225-249 lbs. @ 1.352 in)

 

Great info guys, its just what I was going to say. Although I will say that you will probably be ok with no shims, however take into consideration that over a period of about 100k mi, the springs will lose about 30-40% of their seat pressure, just as the 910s will.

Ron hit it dead on the correct way to measure all of them. But a general rule of thumb for the 910 springs is one .030'' shim will give you a seat pressure of approximately 125lbs.
I ordered my shims for my other springs from summit, the shims with an OD of 1.437''. You cannot run a larger diameter shim than that. It was comp shim kit PN-4754

 

so with shimming its possible to get the same height and pressure (give or take) on all valves?

 

Yep, the installed height with a .030'' shim will put them all very very close to an installed height of 1.775-1.778''. Which is right in the range of 125-130lbs seat pressure. They should all be very very close on the height, and within 1-3lbs of each other.

 

Thanks everyone for the great info, I'm going to order some .030 shims and install one of those shims under every valve spring.

 

dont want to tread jack...but what will new springs do? is it something all of us should look into or just with high hp motors? are there any benefits to doing new springs to a daily driver? thanks alot...just trying to do some learning

 

Yea man there sure is, how often do you hear of trucks that either bend a pushrod or break a rocker arm? I know of several, the stock motor I am tearing apart now had 2 bent pushrods, it was bone stock. There were out after awhile and if you have 300k or so on them it would be a great idea to do so even if all you have is a tuner.

 

i have almost 200k now...and mods are listed in sig. should i be looking to do this maybe in the summer? not sure how to do it, but would like to learn. where are you guys getting parts? thanks a lot for taking the time...

 

i just looked up summit...82 bucks for springs and 19 bucks for shims...why doesnt everyone do it for that price? is it a hard job? any "special" tools needed...maybe that will be a good project for spring fling. any help or info would be greatly appreciated..
thanks again...