Chvyrkr
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I think factory is around 1.8, with most guys shooting for a little less than that to boost seat pressure when they install them.
I don't have my books with me though.
Aftermarket valve spring discussion
- Thread starter Cat_rebel
- Start date
I think factory is around 1.8, with most guys shooting for a little less than that to boost seat pressure when they install them.
I don't have my books with me though.
woodduck97
New member
Subscribed. I have a set of 910's I plan to install in a couple months. Also I have taken my stock springs to 4k and about 30 pounds of boost.
Marty
New member
That's what Matt asked me. The answer is no. So whatever's in my truck is probably installed wrong. :gethim:
Hotrodtractor
Moderator
Not to pick on you but I am so deal with it.
oke:This is what is wrong with threads like this - here we have someone that has taken the stock springs to 4K RPMs and 30lbs of boost - and several people would read this to mean that everything is OK - hell nothing broke right? I would lay money that he has valve to piston contact (unless the motor is setup to not meet manufacturer specs, or he has pistons with valve reliefs cut into them).
Setting up valve springs so they don't float is a function of boost, backpressure, RPM, and cam profile. Setting up valves so they do not contact the valves is a function of piston to head clearance, valve recession (or protrusion), cam timing, plus all the features that prevent valve float.
Personally - I think these motors should not spin over about 3800 or so using the stock clearances provided no matter what valve spring you've chosen.
Evidence of piston to valve contact using beehive springs:
Am I saying that beehive springs are horrible? Hell no - but you'll find that this motor had incredibly tight piston to head clearances as it was setup from the builder - that made the setup not take kindly to RPMs no matter what valve spring was installed.
Evidence of insufficient piston to head clearance:
The point I am getting at is it is about the entire setup, not just one magic bullet part - and just because there is an issue with a setup does not mean it is readily noticeable - no one knew that the pistons were hitting the heads in this motor until I tore it down due to a blown head gasket/coolant leak. No one would have guessed that it had one mis-matched piston, no one would have guess that the decks were cut off plane, no one would have guess that the crank was actually bent. It just leaked coolant. Just because it starts and runs, and nothing noteworthy and noticeable is going on with the naked eye does not mean that everything is all happy and rosey with a particular setup.
Just my two cents on the matter.
Robmamba
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Id use a cumminGs spring.... Make more power that way bro.
That or sell it and buy a honda.
Homesteader
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I got Beehives but it's not the 26120 , but it is a drop in .
Chris
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I ran 910s out of the box without shims and smithbros pushrods. 38r/gt47 combo. Ran between 58-63psi depending on the day and the few times i logged backpressure it was right at 1:1. I never turned the motor over 3800rpms. the truck/motor had 420k miles when i bought it. It got the twins, injectors, and pump right after i bought it and i ran it like that to 440K miles. As far as i know from the receipts given to me when i bought the truck (which is a book about 3 inches thick) the valve covers had never been off. When i bought it, it had less blowby than 90% of 7.3s ive seen. After i ran the PISS out of it for 20k miles, it had about a normal amount of blowby. It did go from running 105-106mph down to 104ish mph, so i think it was finally getting a little tired. It had somewhere around 50 1/4 mile passes, over 100 mud drag passes, and im not sure how many burnouts/powerslides. Im pretty sure if i would have ever driven it easy it would have blown up lol. It did do an outstanding burnout into the shop the day i pulled it apart, so id say it was still kicking. the motor is still sitting on the floor in the shop and i never touched it since it was pulled. The headstuds are out of it now so i guess i can go pop the heads off and take a peak at it. Pistons might look like mickey mouse, or they might be fine. Ill try to snap some pics later.
woodduck97
New member
Not to pick on you but I am so deal with it.
This is what is wrong with threads like this - here we have someone that has taken the stock springs to 4K RPMs and 30lbs of boost - and several people would read this to mean that everything is OK - hell nothing broke right? I would lay money that he has valve to piston contact (unless the motor is setup to not meet manufacturer specs, or he has pistons with valve reliefs cut into them).
Setting up valve springs so they don't float is a function of boost, backpressure, RPM, and cam profile. Setting up valves so they do not contact the valves is a function of piston to head clearance, valve recession (or protrusion), cam timing, plus all the features that prevent valve float.
Personally - I think these motors should not spin over about 3800 or so using the stock clearances provided no matter what valve spring you've chosen.
Evidence of piston to valve contact using beehive springs:
Am I saying that beehive springs are horrible? Hell no - but you'll find that this motor had incredibly tight piston to head clearances as it was setup from the builder - that made the setup not take kindly to RPMs no matter what valve spring was installed.
Evidence of insufficient piston to head clearance:
The point I am getting at is it is about the entire setup, not just one magic bullet part - and just because there is an issue with a setup does not mean it is readily noticeable - no one knew that the pistons were hitting the heads in this motor until I tore it down due to a blown head gasket/coolant leak. No one would have guessed that it had one mis-matched piston, no one would have guess that the decks were cut off plane, no one would have guess that the crank was actually bent. It just leaked coolant. Just because it starts and runs, and nothing noteworthy and noticeable is going on with the naked eye does not mean that everything is all happy and rosey with a particular setup.
Just my two cents on the matter.
Hey that is why I posted stating what happened when I had this tuner on my truck... It only happened one time when I was pulling in the video below. Tuner I now have limits it at 3600 I think. In the video below is that valve float when I down shifted?
http://www.youtube.com/watch?v=8rBzxpsCays&feature=plcp&context=C32a67caUDOEgsToPDskL5gP946L3B8R89Uy_8QteT
Robmamba
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You have a text message captain!
It only takes once to bend a tube or 2.
Sounds like floating
Hotrodtractor
Moderator
Nope.
But I will tell you that the factory calls for 0.010" to 0.031" piston protrusion and that the factory calls for 0.046"-0.058" recession on the intake valve and 0.052"-0.064" recession on the exhaust valve. I do not build to these specs.
PSDEng
New member
Not sure what else I can contribute to this thread other than I'm using comp910s installed to ~1.8. I've seen around 55lbs of boost and 4500 rpm on the dyno. After reading all of this I would wager that if I pulled my heads there would be evidence of contact. Who knows, maybe that's how I dropped an injector tip early in the summer.....
Hotrodtractor
Moderator
You were a case of opportunity - I took it and ran - nothing personal. I don't have sound here at work - I'll watch the vid when I get home.
woodduck97
New member
That is what I want. I want to make sure this thing is right so things wont come apart.
Dieselboy.
New member
I ran 910s unshimmed and bent a pushrod. It did blow the shift selenoid in the trans and blew the 3-4 shift causing an over-rev. Which is when it bent.
I shimmed with .045. If I recall correctly that gives me 124lbs seat pressure.
I shimmed with .045. If I recall correctly that gives me 124lbs seat pressure.
Big Bore
New member
I've realized two things in this thread.
First is when talking to Dave I confused installed height with shim thickness.
Second,.............................the Go Go springs are starting to look better and better. (Yea, the ones I was questioning awhile back)
First is when talking to Dave I confused installed height with shim thickness.
Second,.............................the Go Go springs are starting to look better and better. (Yea, the ones I was questioning awhile back)
Hotrodtractor
Moderator
Its real hard to tell if its valve float from the video - but its a real good chance. I would be real curious to see a data log from when its happening - specifically of RPM and PW. Sometimes with long PW where the FDCS signal gets confused it can sound similar. Just food for thought.
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