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2006 Pontiac GTO
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178 Posts
I don't understand what you mean
Hydraulic lifters are designed with spring open pressures and seat pressures in mind. So, the valve spring you’re showing us specs out to a 405 lb open pressure and 100-180 lb seat pressure at the installed height of 1.8” per summit’s info. So the Morel 7717 lifters have a suggested open spring pressure no greater than 380lb and a seat pressure range of 100-180 lb. You would probably be alright with that part selection as the seat pressure I think is more important than open pressures in regards to lifters but if it were me, I’d spec a lifter that will handle my valve spring pressures.

Then, you need to spec a push rod that won’t deflect under the 405 lb open pressure. And as I stated, the stock steel rockers with a Che upgrade have been widely proven to handle valve train well past 7000 rpm. Some getting over 8000.

Anyway, that’s how I think about part selection. 95% of the rest of the world will just throw a LS7 lifter in with a spring and cam kit and send it with hardly any issues. The other 5% end up breaking shit.

If you have luck like mine, Murphy’s law plays a factor. If you don’t, send it and find out.
 

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2006 Pontiac GTO
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178 Posts
Hydraulic lifters are just that "hydraulic" devices.

Oil viscosity, pressure and internal valving play a role as to what they can handle.

You can't think linear.
You would want to work within the specs of the lifter though wouldn’t you?

In my mind I wouldn’t want to put too much of a lifter on a car because you’ll never push the oil out. Too little and you can create deflection issues. Working within the specs of the valve and lifters would keep the hydraulics happy and allow for you to maintain contact with the cam on the backside of the lobe. That’s assuming a fresh 5w-30 is in the motor.

I’m more so asking than stating in the previous paragraph. Thats how I’ve always thought about it, but I’m always open to some tutoring from more experienced individuals.
 

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You would want to work within the specs of the lifter though wouldn’t you?
Does the lifter know what type of lobe it is riding on?
In my mind I wouldn’t want to put too much of a lifter on a car because you’ll never push the oil out. Too little and you can create deflection issues.
What is "too much of a lifter"? What is "too little"?
Working within the specs of the valve and lifters would keep the hydraulics happy and allow for you to maintain contact with the cam on the backside of the lobe. That’s assuming a fresh 5w-30 is in the motor.
Once again, lobe design plays a huge role.
I’m more so asking than stating in the previous paragraph. Thats how I’ve always thought about it, but I’m always open to some tutoring from more experienced individuals.
Many hours on a Spintrons and at the racetrack are the heartbreakers of internet theories.
 

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2006 Pontiac GTO
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178 Posts
Does the lifter know what type of lobe it is riding on?

What is "too much of a lifter"? What is "too little"?

Once again, lobe design plays a huge role.

Many hours on a Spintrons and at the racetrack are the heartbreakers of internet theories.
[/QUOTE

Question 1: No. lol. (I actually chuckled at that question you asked. 😂)

Question 2: I suppose most lifters have an ideal operating range more so than too much or too little. I suppose I’m more so asking in regards to using a lifter that’s designed for max open pressure at 380 lb when the spring open pressure is 405 lb. Would this not affect valve train stability? To me, lobe design will have an effect on ramp rate but at .650 lift you’re still going to have 405lbs of open pressure…. I guess explain further for me on that one.

Last statement, as I stated before, I’m more so asking rather than stating. Not arguing but rather getting info. I’m always up for hearing peoples experiences and taking things from them for the future.

Me personally, I have a custom grind cam from cammotion, morel 5290 link bars and a pac 1207x with titanium retainers. Manton series 5 push rods (due to the length of push rod I needed with the FED m311 heads) and Texas speed 1.72 roller rockers. I specked it all in regards to cam and spring pressures at open and seat. So, i in a lot of ways over build shit because of how the stupid factor plays in my life. Again, Murphy’s law. I’m always willing to learn or hear of better ways to do things even if I’ve already done it. I can only speak on my experience though and talking to people at Tick, Scoggin Dickey, and Frankenstein.
 

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Yes my name is Holden
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714 Posts
HI Guys; This question is directed to Brad. How can a spring have 100 & 180 lbs. on the seat?? It can't be both! One one thing that the comp tech guy had right is the 875- lifters can handle High OPEN spring pressures. Not to mention very fast lobe ramps. The lobe ramp speed is really what drives the type of lifter you will require.
Since you have already installed the lifters (heads ON) & I assume cam in? Rather than spend More money consider pulling un used (?) cam & asking Comp to exchange it? Or just run what ya got for a while, decide what ya like & don't like about the combo, then do more research & mod the combo in the future? The goddess of Speed rewards patients & research. For instance I kept my last Hot Rod for 40+ years & over time I would up- grade & change the combo. A Hot Rod is Never DONE! The point if ya aren't racin' for money is to have FUN. Best of luck Ole' Bob.
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@vanrah I pulled the lifters and I'm yanking the cam and getting one from @EDC with what Comp Cam's has done with the lifter crap I can't even trust them to select a good cam for me.
i'm guessing ed will probably spec a cam that's less aggressive and easier on the valvetrain than the one the comp tech picked, but will still get the same job done.
 

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2006 GTO Cyclone Gray Metallic, 6.0, Magnuson 112, ported 243's, JBA shorty header
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Discussion Starter · #90 ·
i'm guessing ed will probably spec a cam that's less aggressive and easier on the valvetrain than the one the comp tech picked, but will still get the same job done.
Hopefully I can return this thing to summit racing
 

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Yes my name is Holden
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Greetings Guys; I learned from this post too! As times change ya try to keep an open mind. Since I been fiddlin' with engines since the winter of 61-62 my perspective is that ya can't get enough info. That being said, 20-30 years ago when ya called Comp the tech guy was usually older & more experienced that yourself. Now days that isn't the case. Since I'm now older that most people still workin' for livin'. So I too had an inexperienced tech guy help me & I pushed to try something a bit different. Tthe goddess of Speed bit me! As we have progressed through the LS world for the last 20+ years these small shop builders like EDC, BTC & others all have become the Info well of knowledge! And have added a great deal of Fun to our hobby. Thank you all & good luck Ronin, Ole' Bob.
Ps: I got 99 miles on my fresh build now & second batch of BR-30 in the pan. So far I've restrained myself to 6000 at less than Full On. My right foot restraint has run out, so as soon as I get to 100 miles weather permitting FULL ON coming. Pss; who's going to Drag Week? Byron Wednesday, I'll be there.
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2006 GTO Cyclone Gray Metallic, 6.0, Magnuson 112, ported 243's, JBA shorty header
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608 Posts
Discussion Starter · #93 ·
@vanrah thats so true i used to get my valve train stuff from Comp all the time thats why I never gave it a second thought when they said to run this cam with this lifters and these springs no more...
 

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2006 GTO Cyclone Gray Metallic, 6.0, Magnuson 112, ported 243's, JBA shorty header
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608 Posts
Discussion Starter · #100 ·
Okay I need cam ideas I would like to get this car running in the next week, and I haven't heard anything back from fti going on a week so any recommendations would be great
 
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