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Discussion Starter · #1 ·
okay ive got a set of heads on a mill already built.they are performer rpm aluminum heads.


heres my questions.they have 125lbs seat pressure,installed height is 1.975.open is around 310 suppose to be. coil bind around 1.160.

spring diameter is 1.55.

okay i need around 140-145 for my solid lifter flat tappet cam.can i shim the springs that are already on there to gain the 140 -145lbs seat pressures i need or do i need to buy other springs.if i shim does this change open pressures also:)bulbmaybe dumb questions but i want to learn.:)sphssthey say they are good for .700 lift but my profile will not be this big.thanks as always for any help,travis
 

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okay ive got a set of heads on a mill already built.they are performer rpm aluminum heads.


heres my questions.they have 125lbs seat pressure,installed height is 1.975.open is around 310 suppose to be. coil bind around 1.160.

spring diameter is 1.55.

okay i need around 140-145 for my solid lifter flat tappet cam.can i shim the springs that are already on there to gain the 140 -145lbs seat pressures i need or do i need to buy other springs.if i shim does this change open pressures also:)bulbmaybe dumb questions but i want to learn.:)sphssthey say they are good for .700 lift but my profile will not be this big.thanks as always for any help,travis
Yes , shims will also change the open press.
It depends on what open press. your looking for with the new cam and if you have room to shim them without coil bind problems.
If you dont have the tools, just take them to a machine shop and have them checked, find out what installed hieght they would have to be shimmed to to achieve the 140-145lb seat press then see what the open press would be with the lift that your cam card shows. Dont forget to acount for lash as most cam cards show gross lift and dont subtract for lash.
I'm usually not lucky when it comes to this and wind up buying new springs, kind of anal about having the exact pressures that the cam card asks for.
On a roller I dont mind having 20lbs more open than the card says but with the luck that everyone has been having with the flat tappets loosing lobs, I would go strictly by the card. Good luck
 

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Compress the spring to the required seat pressure. Use this dimension as the installed height. Subtract valve lift and leave yourself .080 - .100 for a margin. Compare this to coil bind. If the installed height - lift - margin is more than coil bind you are good to go.

But you don't want to stack up a ton of shims to get it there. Start at the installed height and compress it the dimension of valve lift. look at the open pressure and compare to what is required also.

Bring them to the shop and we will look at it for you.
 

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Sit N' Spin
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Installed height will determine what your seat pressure will be.

Spring rate and lift will determine the difference between your seat and open pressures. THEORETICALLY, this difference should stay the same no matter what your seat pressure happens to be. In other words, with a spring rate of 350lbs per inch of spring travel and say for example sake, .565 of lift, you SHOULD have a difference of 197.75lbs between your seat and open pressure no matter what your seat pressure happens to be. With a seat pressure of 125lbs, this will give you an open pressure of 322.75lbs. If you shimmed the springs to give, say, 135lbs on the seat, this would change your open pressure to 332.75lbs.

Of course, the above example is assuming the above mentioned spring measures out to exactly what it says it's supposed to measure out to and that the spring rate stays linear throughout the entire spring travel, but you get the idea.
 

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Discussion Starter · #5 ·
okay i guess i left out the part about the motor is together running good and im not going to buy 100 plus dollar head gaskets just to take them to have them set-up at a shop;)

i wouldnt think you would need a ton of shims to add say 15lbs seat pressure?the cam has .612 gross lift.that outta be plenty of clearance if edelbrock says they are good to .700 lift:)bulb

just trying to figure a way to run my flat tappet and get away from hyd.i hate them with a passion:|errand do it without tearing a mill apart.im sure there is a way i can do this:)bulbi have a tool to measure seat pressure with the heads on the mill.i can get a height checker ive never used one but there is a first time for everything.

so what is best without tearing the sob apart trying to shim or buy the correct springs and setting them up on the heads with them still on the motor:)bulb
 

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you're gonna run a solid flat in the tunnel?:)sphss
 

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You can do it on the engine. Measure heights on the engine. Spring pressures are measured off the head anyway.

When I was doing them at home, I used the valve height mic and a spring pressure tester that was hydraulic and used in a drill press or arbor press etc.
 

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Discussion Starter · #9 ·
you're gonna run a solid flat in the tunnel?:)sphss
yeah for this season anyway;)i already have the cam.cant afford what i want to do since i had to finace the boat:|err .the mill is mild anyway the best part is the heads.crane gold rollers and comp stud girdles:D
 

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yeah for this season anyway;)i already have the cam.cant afford what i want to do since i had to finace the boat:|err .the mill is mild anyway the best part is the heads.crane gold rollers and comp stud girdles:D
gotcha, leave it for next winter upgrade:)devil are you gonna sell the sj?
 

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Discussion Starter · #11 ·
You can do it on the engine. Measure heights on the engine. Spring pressures are measured off the head anyway.

When I was doing them at home, I used the valve height mic and a spring pressure tester that was hydraulic and used in a drill press or arbor press etc.
i have compressor,spring changer ect for changing them on the mill,not a problem,just dont know how to check all the shit that apparently is important,lol!!!im willing to learn as i dont trust most places to set them up anyway:)grn

i have a set of 930-16 comp springs,close to new.they will fit but the installed height is different on the srping,the springs are rated at 142lbs seat at 1.95 i think:)bulbso what would i have to do to run them?
 

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mo balls than $cents$
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Discussion Starter · #13 ·
buy this:

http://store.summitracing.com/partdetail.asp?autofilter=1&part=MOR-62390&N=700+115&autoview=sku

if the springs are new, they should be a certain seat pressure at a certain installed height, just get the seat pressure right, then turn the motor over and see what kinda clearence the springs have. every time i had my covers off to check lash, i'd check my springs as well. i went thru 2 sets of springs this past summer.
ive got that already loser:pthats excatly what i have:)hand
 

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You can shim your existing springs for more seat pressure, and it'll give you more open pressure, but probably not enough because you're not changing the spring rate. The solid flat will probably require a higher rate spring with more open pressure. Compare the spring rastes between what's in the boat, and what the cam you want to use calls for and see what the difference is. That'll tell you if you need to change springs. With the right tools, it's a slow process with the head on the engine, but not a difficult one. If you need springs, let me know. I have some excellent quality inexpensive springs that should fit the bill.
 

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Discussion Starter · #16 ·
You can shim your existing springs for more seat pressure, and it'll give you more open pressure, but probably not enough because you're not changing the spring rate. The solid flat will probably require a higher rate spring with more open pressure. Compare the spring rastes between what's in the boat, and what the cam you want to use calls for and see what the difference is. That'll tell you if you need to change springs. With the right tools, it's a slow process with the head on the engine, but not a difficult one. If you need springs, let me know. I have some excellent quality inexpensive springs that should fit the bill.
thanks steel ill do that.i have to call crower and get a new cam card to find out what it wants for springs,or maybe look it up on the web:)bulb
 

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i have compressor,spring changer ect for changing them on the mill,not a problem,just dont know how to check all the shit that apparently is important,lol!!!im willing to learn as i dont trust most places to set them up anyway:)grn

i have a set of 930-16 comp springs,close to new.they will fit but the installed height is different on the srping,the springs are rated at 142lbs seat at 1.95 i think:)bulbso what would i have to do to run them?

We use those 930-16 springs on some of the hydraulic roller set ups. They set up usually 152 lbs at 1.900
 

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Discussion Starter · #18 ·
We use those 930-16 springs on some of the hydraulic roller set ups. They set up usually 152 lbs at 1.900
yeah these are on set of oval port heads that are thrased.had maybe 10hours on the springs.if i remember right they were suppose to be set-up at 1.90 145lbs for the hyd roller it had.:)
 

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Discussion Starter · #19 ·
i cant get ahold of crower but the part # to the cam is 01351. solid flat tappet 252-262-601-620.i cant figure out there damn website to find the springs needed for the sob so i can get pressures and height info anyone wanna help.:p
 
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