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We'll, against my better judgment I let the machine shop setup my iron BBC Vortec heads. Told him I'm running a ZZ502 cam and would like something like ~140-150 on the seat and about 350 open. Pick up the heads and he's got 924-16 Comp springs on there. Argued with him, and he said this is what Comp specs for a similar cam. Its about 112 seat and 300 open. I can shim up a bit or install -.050 locks. Will this wear the spring out faster or just take the hit and get something like the 930's???

Thanks as always.
 

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You would have to shim that spring almost .100" to get to 140 seat pressure and then you would probably be real close to coil bind. The spring that GM specs for that cam is 140 seat so you probably are right in wanting to change them.
 

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The Comp 930 springs are almost an exact match to what GM recommends plus they use the same retainer as the 924's so it should be an easy swap as long as he has the installed hgt correct. I have personally never had a problem with Comps springs. The Isky 8005A uses a different installed hgt and probably a different retainer and they are also a higher spring rate so they might give too much open pressure.
 

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I like the 929 springs. I used them on my solid lifter 408. Went to 7000 easily with 3/8 stem valves.
 

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As Bill said, even if I shim these springs by .100, that puts the seat pressure to 146 lbs but open about 335. Not sure if that is adequate but the GM lifters are a little lighter than most lifters. Probably just swap the springs as long as they fit the retainers.
 
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" this is what Comp specs" It seem he may not have enough experience, or common sense to pick his own combination? Or if it comes back it's Comps fault.....
 

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I am running the low-lift ZZ502 cam; less than .550" lift. Are these pac racing springs good?
I already have them and am planning on using them.
Have you meassured your installed height so the spring is a good fit on your heads.

what lifters?

@ springs recomended installed height you will have [email protected] lift and [email protected] lift personally I would prefer little more open.
 

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am running
i would not hesitate. The spring is slightly more than your requirement keeping in mind the retainers are substantially lighter the conventional barrel valve springs. it would provide a good margin of safety for valve train control.
 

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i would not hesitate. The spring is slightly more than your requirement keeping in mind the retainers are substantially lighter the conventional barrel valve springs. it would provide a good margin of safety for valve train control.
Thanks (y)
 

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I am running the low-lift ZZ502 cam; less than .550" lift. Are these pac racing springs good?
I already have them and am planning on using them.
YOU need to check installed height, they may not be good for your heads?
but just threw them in and run them with 2.00” installed height youll soon see what happens.

Personally I would use a dual spring over a beehive, what Do you think happens If a single spring breaks? With a dual there is better chance engine will survive. BBC Valve train is heavy. 150lbs seat 380 lbs [email protected] lift If you dont have good lifters that can take 400 lbs. anyway If 454 it will be done @5500 If larger like 496 5200 rpm and it will run out of steam.
 

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I am running the low-lift ZZ502 cam; less than .550" lift. Are these pac racing springs good?
I already have them and am planning on using them.

I would shim the duals you already have over those beehives some like Wolfplace suggested and like you got suggested in two more threads.





Especially since I guess you using cheap street lifters and stamped steel rocker arms?
 

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I started a thread but in truth just needed to reread a few to get my answers lol
Beth I would just shim the current springs and run it for now, I am going to do that with the same cam used in the zz502 used in the article listed above, bet it works out fine till I can afford to upgrade.
 
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