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  #16 (permalink)  
Old 10-03-2010, 09:36 PM
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Good catch Techinspector . You're right, all I did is went to Lunati's site and looked up the cam card, it gave a recommended spring(73943) and I looked that up to see what the specs on it were...but I didn't look any further.

I should have known better than to go against my instincts of 108 lbs seat load not being anywhere close to enough, both of the other springs given for this application both have 20-25 lbs higher seat load than the 73943 spring, and are right there with what I recommended in my earlier post.

I just don't see 108-110 lbs seat load getting the job done with this cam, the largest of the Voodoo hydraulic flat tappet cam line. No way the largest and smallest of this group of cams can use the same spring, but some of Lunati's information shows it that way, while in other areas of the catalog it is different.

Pretty bad when the company that makes the cam can't even give reliable info in their own catalog.

I'm still convinced the problem is valve float in the OP's case with his engine.

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  #17 (permalink)  
Old 10-04-2010, 06:27 AM
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This cam series in finicky about springs

Quote:
Originally Posted by ericnova72
Good catch Techinspector . You're right,
Pretty bad when the company that makes the cam can't even give reliable info in their own catalog.

I'm still convinced the problem is valve float in the OP's case with his engine.
I always disconnect the tach early in the game when this comes up to eliminate that possibility. Sounds like they'e on top of your problem though. This cam series in finicky about springs.
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Old 10-04-2010, 10:34 AM
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thanks for the help , sounds like springs are the big issue.
my engine shop guy is supposed to call lunati and talk with them so i hope they give as good info as techinspector did.

When i bypassed my ingnition system i also bypassed the tach and didn't use one on that test.

it runs great up till 5600, smooth the whole way
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Old 10-04-2010, 11:32 AM
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update

just got off the phone with lunati tech and he said basicly what techinspector said and that I might need the duals or honeycomb springs but it depends too on how these springs are set up as far as open seat pressure is set and he thinks the 110 is a little light.

And he thinks the lifters should be fine that came with the cam.

Now i worry that the machine shop either is too old school to set springs right or didn't care enough for my engine.

i'll find out soon i guess when i hear back from him.
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Old 10-04-2010, 09:37 PM
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When I looked at the recommended springs myself for this cam I thought the same thing, 108 don`t sound like enough but I`m not exactly one to argue with what the cam company recommends either. I`ve seen guys run flat tappet springs on roller cams cause the lift number was over the cams and I tried to explain to them there`s more to it than just the lift, that the aggressiveness of the roller design over the flat tappet plus open pressures was what you had to pay attention to. As time`s passed the flat tappets have gotten more aggressive with advanced lobe designs so the springs had to step up to the plate as well.
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Old 10-05-2010, 04:04 AM
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As time`s passed..... springs had to step up to the plate as well.

Quote:
Originally Posted by DoubleVision
When I looked at the recommended springs myself for this cam I thought the same thing, 108 don`t sound like enough but I`m not exactly one to argue with what the cam company recommends either. I`ve seen guys run flat tappet springs on roller cams cause the lift number was over the cams and I tried to explain to them there`s more to it than just the lift, that the aggressiveness of the roller design over the flat tappet plus open pressures was what you had to pay attention to. As time`s passed the flat tappets have gotten more aggressive with advanced lobe designs so the springs had to step up to the plate as well.
When I first noticed spring rate going up for flat tappet a decade or more back, I thought they were selling springs. I don't think that now..
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Old 10-05-2010, 04:27 PM
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my engine says today that the springs are fine and that he builds round track cars and these should run fine over 7 grand.
he says that "micro-trol" lifters will fix my problem.

what do you all think?
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  #23 (permalink)  
Old 10-05-2010, 04:54 PM
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Quote:
Originally Posted by wadedog
my engine says today that the springs are fine and that he builds round track cars and these should run fine over 7 grand.
he says that "micro-trol" lifters will fix my problem.

what do you all think?
Maybe he knows what he's talking about but I'm still a spring guy on this issue.
If you did try springs and it didn't help you could Ebay the springs, or if it did work you could ebay the old springs, which would be fine for lots of applications, and save the intake removal. Because you can use an adapter to air charge the cylinders and replace the springs without removing the heads.

Or the guy might be right. I don't know.
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Old 11-08-2010, 12:11 AM
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Do the heads have to come off to change and shim the springs?

My engine guy still says anti pump up lifters are what i need !
Its hard to talk to him about springs, i'm worried he is too old school and not up on the new voodoo cams.

I read this on popular hotrodding.

You may have heard the term "anti-pump-up lifters." These are intended to fix a problem that can occur toward the top 25 percent of the engine's rpm range. What happens is that the spring starts to lose full control of the valvetrain and separation between various components takes place. This, as far as the lifter is concerned, looks like lash, so the lifter does it's job and takes it up. When the valve now tries to close, the lifter, which is now a little too long, holds the valve off its seat and heavy-duty power loss takes place. For many years, the accepted fix for this was an anti-pump-up lifter, which was a much leakier, faster-collapsing lifter that allowed the valve to physically close unimpeded. But it also collapses easier and consequently cuts valve lift. The real fix is a spring with better control. That's a serious topic we will talk about later.If valvetrain noise is of little or no concern, then a solid cam is the way to go, as there are no worries about hydraulic lifter collapse.

http://www.popularhotrodding.com/tec..._pushrods.html


the 74818 shows it's for the ls1 engine, what one do i need for a older standard small block

Last edited by wadedog; 11-08-2010 at 12:27 AM.
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  #25 (permalink)  
Old 11-08-2010, 12:58 AM
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Do the heads have to come off to change and shim the springs?

Quote:
Originally Posted by wadedog
Do the heads have to come off to change and shim the springs?

My engine guy still says anti pump up lifters are what i need !
Its hard to talk to him about springs, i'm worried he is too old school and not up on the new voodoo cams.

I read this on popular hotrodding.

You may have heard the term "anti-pump-up lifters." These are intended to fix a problem that can occur toward the top 25 percent of the engine's rpm range. What happens is that the spring starts to lose full control of the valvetrain and separation between various components takes place. This, as far as the lifter is concerned, looks like lash, so the lifter does it's job and takes it up. When the valve now tries to close, the lifter, which is now a little too long, holds the valve off its seat and heavy-duty power loss takes place. For many years, the accepted fix for this was an anti-pump-up lifter, which was a much leakier, faster-collapsing lifter that allowed the valve to physically close unimpeded. But it also collapses easier and consequently cuts valve lift. The real fix is a spring with better control. That's a serious topic we will talk about later.If valvetrain noise is of little or no concern, then a solid cam is the way to go, as there are no worries about hydraulic lifter collapse.

http://www.popularhotrodding.com/tec..._pushrods.html


the 74818 shows it's for the ls1 engine, what one do i need for a older standard small block
No.........The heads don't need to come off. It takes a couple of hours start to finish.. You buy a little adapter to air charge the cylinders one at a time. Before you could easily find one at NAPA we use to gut a spark plug and weld a 1/4 pipe nipple to it add a 1/4 pipe coupler, thread the air hose onto it and go.
Remove the rockers for a cylinder. Put the nut back on a few threads down. I guess NAPA has the prybar looking tool to go up under the nut and prize down the spring. If not you can make one from a Wonder bar using a Dremmel. We still have one we made years ago.

Air charge the cylinder, spray a bit of carb cleaner to soften any shellac, use a deep-well socket over the spring and give it a couple of whacks with something light. We have a socket with a magnet glued in it to prevent losing the keepers. Prize down on the spring and the valve stem comes up through the hole in the tool; use a magnet or needle nose pliers or both to remove the keepers. Swap out the springs, replace the rockers, and move to the next cylinder. It's better with two people. I keep a big towel stretched out for a safety net.
I'm sure someone here can tell you what springs will work.

Ps. Don't be alarmed if you have some minor air leakage through valve seats, out exhaust, back through carb or out of the valve cover like blow-by<<<< but pay attention. Best diagnostic tool I ever discovered. easier than it sounds... just do it..
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  #26 (permalink)  
Old 11-08-2010, 01:41 AM
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While you can go the air pressure route, I perfer the rope route. Get some small rope. Remove the spark plugs. bring the piston about halfway up in the bore on the compression stroke. Feed a good amount of rope into the cylinder, bring the piston up until it stops. This way you can do so without the worry of popping a valve and watching it drop as can happen with the air pressure way of doing it.
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Old 11-08-2010, 02:12 AM
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I have to concur that I DOUBT it's the lifters, and indeed, you need a more appropriate spring.

I'm running a really mild Summit Racing cam with their lifters, but I have a "head improver kit" from Competition Products, and I have no issues running my engine well past 6000 rpm. I know from a missed shift that I start running into valve float around 6600 rpm, and bad things start to happen at 7200 ... (I ordinarily shift right @ 6000, and have a rev limiter @ 6200 now)

basically, I don't think summit would provide high end lifters in an $80 cam & lifter kit and I don't suffer lifter pump up, so I doubt your Lunati lifters are doing it either.
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Old 11-12-2010, 12:03 AM
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Thanks, so can I just remove and replace the springs without doing any adjusting with shims ?
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Old 11-12-2010, 12:54 AM
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that depends on the spring.. that's why you have to measure installed height and all that crap.. that's why I paid the machine shop to install my new springs so they'd be done right lol
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Old 11-12-2010, 10:27 AM
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ah, thats what i'm thinking now too.

I talked with tech at Lunati today and he said the recommended pressure is 108 closed and 330 open, so maybe my engine guy did set the springs right at 110 lbs.
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