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ok, so i'm building a motor for a stock/budget class of circle track racing. i'm using a set of 882 heads on a 350 motor. the cam is a melling ccs-2; it's a stock cam. all i've found are these specs: Lobe lift(Intake) 0.2600" Lobe lift(Exhaust) 0.2733"
which one of these sets would you recommend?
http://www.daymotorsports.com/produc..._RETAINER_KITS
my first post btw, been reading a lot this morning before i joined, seems like an awesome site y'all have here.
matt
From what your link provided I would choose VSK-0001
Be sure to add ZINC additive to the oil if you want to keep the lobes on the cam.
thanks for the info, as far as the zinc ill be running a racing oil that includes the zinc additiveQuote:
Originally Posted by Bouncer
This is an interesting exercise for those of you who like to play with numbers (like me :3dSMILE:) .
0.2600" intake lift at the cam will theoretically be 0.390" intake lift at the valve and 0.2733" exhaust lift at the cam will theoretically be 0.410" exhaust lift at the valve with a conventional 1.5 rocker arm. I say theoretically because I don't think there ever was a true 1.5 stamped steel rocker produced by Chevrolet. Every one I ever checked was less than that, with some down around 1.45:1 as I remember. That's one of the reasons to purchase aftermarket rockers, because you get the true design lift at the valve. At any rate, we'll consider that this young man has some 1.5 rockers and that the valve lift is 0.390"/0.410".
Pro-Tek didn't supply us with the spring RATE, but we can figure it out.
Coil springs are pretty much linear as you apply pressure to them, so if the VSK-0001 springs are 103 on the seat and 300 lbs @ 0.500" lift, a difference of 197 lbs, then we can divide 197 by 500 and find that for each 0.001" of lift, the pressure increases by 0.394 lbs.
Now, if we multiply 390 times .394, we find that the pressure will increase on the intake by 153.66 lbs from valve closed to valve open at full lift. Now, if we add the seat pressure to that (153.66 + 103), we find that the intake spring pressure is 256.66 lbs. over the nose. Multiplying 410 times .394 will tell us that the exhaust pressure increase is 161.54 lbs. Adding 161.54 and 103 will tell us that the exhaust spring pressure over the nose is 264.54 lbs. We can drop the decimals and just call it 256/264.
Now, since we know that pressed-in rocker arm studs begin to pull out of the heads at pressures around 250 lbs and higher, we now know that we must either pin the studs or pull the studs, tap the holes and install screw-in studs or we can mill the pads, tap the holes and install screw-in studs with guide plates.
http://www.summitracing.com/parts/MRG-806G/
the LT -1z-28 is one spring for mild use 120@1.700 300@1.250 cb 1.160 there some things over looked here mass weight come s in to play as well . and if stock parts the set up should come in at 1.700 or 1.750 so you would look at installed set up height. as what spring to use for what rpm s . you may want to buy some good pushrods . for what your doing. i use the spring i listed . they can be had for $30. a set thru comp products in a kit form as well . you could pin rocker studs or get screw in studs or what ever way you go but Dorman made a stud that was 3/8 by 7/16 that did not need to be milled for the stud towers when this is done . but i got away with out screw in studs thats up to you but in time you have chance of one pulling .pining them is a fast way to fix this and Ez to do the screw in studs are not hard to do but eats up alot of time=$$ . i have seen guys screw the up doing them so find some one that can do the job if not then pin them your self this take less time and money and if you do not have alot of tools you can do this job at home EZ . i changed my mind on pinning studs after hearing about guys screwing up good heads trying to do screw in studs . when i do a set of heads i also drill out the push rod guids and then use guid plates so i spot face the stud tower down and you need a hard face push rod to run on the guid stock ones will not work
Matt, the Z-28 spring is available from many sources. Here it is from Scoggin-Dickey....
http://sdparts.com/details/scoggin-d...-center/sd1004
The advantage in buying from the source you linked is that you get springs, retainers and locks for 60 bucks. Not a bad deal at all.