cardo, how about the fact you are trying to apply aftermarket info to a stock cam application? The stock cam is lazy. Lost power from valvesprings is as I said due to valve bounce.

Ask wrd1972 about his experience fixating on open pressure vs. giving a cam the closed pressure it needed. He wasted the time effort and money for a spring swap and dyno time.

Try and find some racing related info on "lofting" and you will find springs run intentionally soft over the nose to let the lifter be thrown for extra lift. Most often done in lift limited classes but I have seen it done on street cars so that the springs can be beaten up with moderate lift at cruise rpms but then when at high rpm the lifter is thrown giving more lift.

You want to dig around cam companies websites and you will find Comp describing using flat tappet breakin proceedure and suggesting it for all cams which has lead folks to think roller lifters need the same breakin. The website stuff isn't put together by top engineers, more the marketting department.

 

Your nuts, you have so little self esteem that you suggested something that could destroy someone else's valve train and engine just so u don't have to admit your wrong. There ain't no cam manfr out there selling lofting cams/vlv trains for street engines - none period. If there was any horsepower to be made there would also be money for a manfr if they could get it to work reliably. But it remains at best an experiment for street cars. To encourage low open pressure because some race team knows how to make a vlv/lifter "loft" is fabricated BS just to hide your lack of knowledge. So have u ever yourself built a vlv train that "lofts" the vlv? How much more hp did u make? Where are the dyno graphs to prove it or did u just feel it in the seat of your pants while driving? How long did that vlv train last? Oh, and of course i can imagine u got it right on the first try didn't u???
U need to dig around cam companies and find out why open pressure is so important to controlling the vlv and how harmful vlv float can be.

U should apologize to the novice hobbyist for your terrible advice,
cardo

 

Ya, i to am sorry some else had to derail the OP's thread and start talking part subsitutions without any proof - just throw out some more hearsay like that is has helped the debate at all.

So now your saying they/GM substitutes parts with different numbers without giving notice of superseded part numbers? Or are u fabricating how GM does business? I find that hard to believe as i look at my GMPP catalog which lists superseded numbers for discontinued parts right in the catalog. U must be able to justify every mistake u make that way - great scape goat reasoning. Heck how would i know if all my pistons and rings are the same. Or my bearings? Heads? Manifolds? Sensors? Camshafts? Crankshafts? Connecting rods? Heck who knows, maybe then even a Ford part is in the box???

cardo

 

You wont get a lofting cam by opening a catalog and ordering a cam from there but they ARE on the street.

You are fixated on over the nose valve control tell me how a lack of control there hurts power? I already stated that the way the valvetrain getting out of control hurts power is when valves bounce off the seat effectively opening them when they should be closed, letting the intake valve pop back open slightly after it should be closed losing a little charge. Can you explain how the lifter getting thrown a slight amount at high rpm in the case of "too weak" springs would HURT POWER?

The fact you are arguing the superceeded PN thing is going to be the end of anyone mistaking you for knowledgeable since the LS7 lifter thing has been common knowledge for a long time, the MAF are another example of LS parts superseding LT1 parts on this particular car. If a part fits basically the same and functions the same the practice is common.

Nice to see you resort to personal attacks.
Now let's see your technical explanation on how extra nose pressure adds power.

 

Just to further drive home the point about how wrong you are on the topic GM specifically markets the HOT cam kit for LT1 use, that is .525 lift on those springs with that spring and LT1 valves and here you are arguing against it with 1.6s on a STOCK cam.
Many guys use the LT4 springs with a HOT cam on stock LT1 heads happily. Some of us just argue they are leaving a little on the table because the springs are marginal for that. I believe they are just the old "Z28" spring that had been in the parts bin for decades anyway.
GM uses the LT1 TB on the 502 RamJet, bet you argue it was all carefully engineered.

Bringing a new part to market or keeping new stock onhand for obsolete engines is expensive and they will consolidate PN whenever possible.

 

Now u admit no cam mfr sells a lofting cam. But u can't admit encouraging weak spring open press and creating vlv float is bad advice. Where lofting ends and vlv float start i admit i don't know but i have enough sense not to encourage others let alone novice beginners to accept it when choosing vlv springs. And u don't know what all it takes to loft a lifter/vlv without causing vlv float otherwise u would have already posted it.
This goes on and on and on because your encouraging beginners to do something u don't know what your doing.

And now what, my reputation is at stake over some LS7 lifter? U just keep looking for something to discredit me now since i reveled your dumb idea to loft a vlv. If that ain't personal attacks then what is? And i'll look into this LS7 lifter part number when i get the time.
But what is it now, a stupid throttle body? How the heck does a TB relate to vlv lofting? Only because u may actually know something about TB's and want to argue that now - rather than making a vlv float from too weak a spring open press. Or the LT4 Hot Cam kit? U want to argue that too? Your getting more desperate by the post. Ya so what the LT4 Hot Cam kit is now the 350 Hot Cam kit and recommended for the LT1 for "showroom racing" (what ever that means). That doesn't say anything 'bout top rpm or lofting vlvs for either LT4 or LT1 motors. Do u expect the hot cam kit to make more power on the LT1 due to vlv/lifter "lofting"? I sure as heck don't.
Your post #9 even says my comments would be accurate for the Hot Cam - where the open press difference between springs is even greater - but not for the stock LT1 cam. But its the same situation, the LT4 spring has higher seat press but less open press. But again the facts are the LT1 vlvs are 20% heavier and the LT4 vlv springs make less open press to control the vlvs. Hot cam or stock cam its the same situation with those springs - though to a lesser degree with the lower lift of stock cam. But what tee's me off is instead of admitting your error or even just shutting up u try to BS around the issue and give bad advice about lofting the vlv/lifter is good - completely ignoring the possibility of vlv float. The cure is a better vlv spring.

Your not a complete waste of time though as u make a good sounding board so others here can decide for them self's and know what they are dealing with when u post on their threads.

Enough for today, i have to get some work done,
cardo

 

A bastard child engine!! That's gotta be the funniest thing I seem in a while. Thanks for all the input guys. I am probably just gonna hang on this summer enjoy the car and when winter rolls thru here in southwestern pa. (6mo. Of snow and shitty weather) I will get the Lloyd Elliot headwork get a cam from him and do everything as my winter project. Go with the long tubes and everything. May stick a nice nitrous kit on this yr yet. And keep the spray on a safe level for the stock parts.

 

I bought the accell 24lb hr to get as close to stock so I didn't have to tune the car I had to replace all my fuel system about $1000 and that was only parts I did the work. So I was tapped out and couldn't get an answer abou the ford Svo injectors everyone recommends for a good replacement. I personally like the accels. We will see what happens with them later on. Hopefully they work out they were almost $300

 

I will keep everyone posted on my results as I do make my mods. All these numbers are making my head hurt! Lol.

 

There is two things you need to consider.

1. You need to choose the right spring for your RPMS and valvetrain.

2. If you think you make more power from springs and rockers you are looking in the wrong place.



When you install a quality spring, that is correct for your application then you gain the ability to control the cam events and reliability. There is a minimum that you need for your application and then there is overkill. You obviously don't need 350lb on the seat and over 1000lb open pressure, but if you are running to 10500rpms in a nitro nastagia then that's what you would need.

This is all irrelevant if your quality parts are installed incorrectly. As far as lofting, save that for the people that are limited by rules and run on money and valvesprings.

 

I was not suggesting anyone here intentionally loft their valvetrain. My point was that "too little" open pressure is in more aggressive cases used to ADD POWER through more cam lift and that a power loss from weak springs comes from too little seat pressure letting the valve bounce open.
Cam companies certainly do sell lofting cams, they just don't have them in the catalog, it is a very delicate balance to strike and the whole valvetrain generally sent and tested on a Spintron, you try and assemble the setup with a wrong component and you completely upset the balance. It is a little on the exotic side and like I said I am not suggesting anyone here do it, but it is a definitive example of how "too little" nose pressure is used by some to add power.

I still want to see cardo explain exactly how too little open pressure hurts power. By what means is the power lost?
I already explained that too little seat pressure cost power by not sealing the intake valve and letting it bounce open allowing intake charge to escape.

You are the one dodging the question here.

 

After 1100 open pressure, even the low end jesel's will fail.

 

I already answered this in posts #15 and #19. What do u want now? A detailed dynamic description at the molecular level? Your a waste of time. Your not worth wasting any more time, information or good advice. Any good information provided to you gets distorted and or ignored. I think u have mental and emotional problems and in need of medical help. If u don't like my answer then call a moderator or call a cop.

U have proven your true mentality and i have to restrain myself from giving u the reply u deserve,
cardo