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Discussion Starter #1
I guess y'all should have seen this coming. I went back and looked at the spec's on my current valve springs. I'm wondering if I was pushing it to get that what I have gotten out of these even when they were new. A phone "tech" said my current springs just need to be freshened up but I'm not sure I trust that opinion. Frankly, I don't have a clue beyond looking at what the cam spec's recommend.

Current are 132 on the seat, 293 open load, 322 pounds per inch, dual springs with a damper. My cam called for either these or another spring that is spec'd at 121, 343, 370. It seems odd to me that this would have a lighter pressure on the seat. This spring would require deepening the valve pocket a little to get the pressures to spec.

Another valve spring that looks to be perhaps the next step up is 165, 346 and 366. Same dimensions so no extra valve pocket work needed, also a dual spring with a damper. Do I really need these though?

I see some spring spec's that seem heavy on the seat and a bit lighter on the open load and others that are lighter on seat pressure and heavier on open load. I don't understand. It is too confusing for my simple brain.
 

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Some info por favor:

  • lifter type
  • full cam spec's (.004/.006 and .050 and graph if possible)
  • rpm you expect to hit regularly
  • rocker type, material and ratio
  • valve diameters and specific material
  • head and seat material
  • pushrod size and material and wall (thin, std, hvy)
  • current installed height IN & EX
and if you have it:

  • current test results for seat, open and rate
or whatever you have.

David
 

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Discussion Starter #3
Errr, gee Wally, LOL. I will try and do my best.

stainless steel roller rockers, 3/8 1.6
solid flat tappet lifters, 109 grams I believe so not the lightest around maybe
248 @ .050, 106 ICA, 110 LSA, .560 lift both sides, .022 lash(currently running .017)
valve timing
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exhaust closes 33 atdc
opens 81 bbdc
intake opens 41 btdc
closes 73 abdc
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Manley stainless pro flo valves - 1.94, 1.60 Chevrolet
heavily ported iron heads, seats are as cast plasma hardened right now
may need new seats when I take the heads in, don't know yet
5/16 chrome moly heat treated pushrods, .08 wall
10 degree chrome moly retainers and hardened keepers
132 @ 1.75, 293 @ 1.25, 322 rate, coil bind at 1.15

I'm looking for a run out to 7200.
I haven't tested the valve springs as they are right now(yet).
Why do we need all this stuff?
 

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Find some behive / conacal springs gets rid of a lot of weight single spring a lot more rpm . I went from 6400 rpm valve float wit hduals to some were over 7200 rpm. Probably will go further havent had time to push it further. currently hyd cam 155 seat 460 open
 

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Cool, let me do some searching when I get a break later to see what I can find. The purpose of the info is to see if anything nudges the spring characteristics one way or another. For examples - heavy parts mean more spring rate. Aluminum heads mean less seat pressure. Fast opening ramp rates means more rate, and slower closing ramps need less seat. Using a damper spring reduces seat pressure required, but very hard valve material tends to need more. Anyway, it's a balancing act and I'm looking for obvious trends. Turbo is correct, at over 7k valve train stability becomes critical, and anything that flexes is difficult to control with pressure. Who's your cam grinder?

David
 

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Discussion Starter #7
Comp cams. With my little baby motor I thought the 3/8 ARP studs would be ok.
 

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Comp cams. With my little baby motor I thought the 3/8 ARP studs would be ok.
I wouldnt use 3/8 studs in a stock motor if had to buy all new stuff. ARP good stuff and using there poly locks are sweet. Have had to use others poly locks because of spacing but there setscrews are what makes them.


Heads up on the bee hive springs there a progressive rate spring so they open and close quicker. The less wt on the valve is better. removing weight on the cam side dosent always help.

Wouldnt call that a baby cam. Ran something close to that in my 84 stang wit ha VRJr
 

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Note that you won't be able to swap from 3/8" to 7/16" studs without also changing out the rockers too. Also if you are going to spin over 7K each shift, its probably time for a stud girdle (or better yet shaft mounted rocker=$$$.)
 

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For a conventional double spring... probably a spring around 140 on the seat, and around 300 over the nose.

For a beehive, you can drop those down a little, but you'd need new retainers.

Be sure to check the spring height, as if they are installed at the wrong height, it makes a huge difference. For a 300lb/in spring rate, being off 0.100" = 30lbs.

Good Luck!
 

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Me thinks you're out-running your cam. While you can make anything rev to the moon, there is a point of diminishing returns in power and stability. You're running pretty hard for that cam. If I were running it the way you are trying to, without adding any stabilization, I'd just swap for Comp 987's to test theory as they are common and cheap. I just passed a set on Fleabay for $40 + shipping. Beehives (not the ones they recommend) would be choice 2 only due to expense.

Honestly, I'm surprised they recommend 986's. I did an X4270H that only lifts to .512/.531 and rated 5800 rpm that used 986 with 987 as their recommended upgrade, and hydros use less pressure than mechs. The 987s with seat at 1.750 will be about 139#, but 346# at .560 lift. The higher pressure at lift will help stabilize the springs over the nose so the harmonics are reduced on return with less bounce on closing. Are you sure of your installed height now? If it's more than 1.750, then I'd shim-up or down-lock what I have (if springs are in-spec and no coil bind) for next to free or go straight to 987s to test results.

Without stabilizing tricks, you are gaining some return control, but losing some in increased flex. Bottom-line from your description is that I'd re-gear or tire-up to bring the trap revs closer to where the cam should be falling off. These are ideas for experiments to determine where to go from here. If you just gotta rev, re-spring, stabilize the train, and cam-up. A narrower split cam of similar lift should keep your peak up and avoid losing the launch and some streetability.

David
 

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Discussion Starter #12 (Edited)
Ok, the plan.

Springs. 987's. Changing installed height so I'll take my heads to my machine shop. Valves and seats probably need a clean up anyway.

Tires. 27 x 10.5 ET Streets or 255/60 15. My current tires have a few runs left in them but they are about shot.

Please send money.
 

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LOL. I feel ya. I wouldn't pull the heads unless there are other pressing needs. You should be able to do the spring swap and set proper height on the engine. As this is more of an experiment than a final solution, I'd go for the cheap angles for now. Do you know your current actual installed height on your setup now? If so, we can figure the best combo of pieces to get to the target so everything is in one bucket with you when you pop the hood to do the job.

David

PS: Do you have a stud-mount spring compressor or what?
 

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Discussion Starter #14
I don't have the spring checker or even a height mic. I used to have a friend I could borrow that stuff from but he's not around anymore.

On just a stock rebuild they don't do all this but on my hot rod stuff the shop checks every spring to every valve spring pocket for height and correct pressure. I would guess they are all right at 1.75(give or take a hair). The valves went into the heads new & seats new so the seats weren't ground. Alls they did was lap the new valves to the seats and leak test them. I don't have any shims so apparently all the pockets had to be cut some amount to be correct for my current springs. I bought my heads bare and put my own stuff in them.
 

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I have found from experance and others that coms spring choices are not too good. Several friends have picked upwards and over 1000 rpm on there cams running stiffer springs. They are real off on heads with heavy valves such as a big block. I feel into there trap a couple times but never again.
Bee hives wouk well on most anything if the right combo can be found.

I had a long conversation with Ferrea about it some time back.
One can get a handle on installed ht just using a machinest scale to ball pak the dimension. There are tricks though. Retainers can change installed ht so can keepers. Crane is one of the few that list + or - on retainer dimensions. It can become a real pain setting up proper spring rates and installed hts.
 

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Discussion Starter #17
The spring spec's for 1.75 installed height. The 987 comp springs which are the other option call for 1.8. These have a bit less pressure on the seat but more open and more spring rate. Kenny at my machine shop said that I should be running the 987's probably. I didn't ask him about bee hive springs.
 

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Installed height is whatever you want. The listing is a reference at 1.800" so you know what the pressure is at that point. You can install at 1.750 or anything else that will function for the pressure you want, as long as it does not hit coil bind. As we were looking for about 140# seat, the target would be 1.750", an you can hit that with any existing head spring seat location. There is no machining required. Period. That's why I said just do it in your driveway on the engine. I don't want to start pointing fingers, but I'm surprised your machinist isn't telling you this, or telling you clearly.

Beehives, ovate-wire springs, titanium retainers and such goodies are great. But, unless you're at the ragged edge and are running out of options, I save the expensive fixes for last - especially in the experiment or debugging stage you're at right now.

David
 

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Discussion Starter #19
I thought that installed height number was magical somehow and not something to mess with. I only asked Kenny why they might spec 2 different sets of springs for the same cam and gave him the numbers. I didn't mention the different installed heights to him on the phone. His shop has done good with my stuff for several years now. They also build a lot of circle track engines because running around in the dirt is a big deal down here for some reason. Now that our quarter mile track is back open the drag stuff has started to pick up too.
 

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Cool. I hope I didn't sound grumpy - I was just trying to catch you before you committed to time and money that isn't necessary at this point. Keep in-mind, although a spring upgrade will generally allow 7200, it doesn't mean you're not out-running the cam anyway. It should tell you if you are, and what next move is best. Best bang for the buck and all that.

David
 
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