Local LT1 Stock Eliminator Car
06-07-2011, 06:12 PM
#41
LOL what happens when you "loft" a valve with hydraulic lifters?
Even if we're talking a solid lifter, you'd have to make compromises on the closing ramp to avoid bounce off the seat, which would hurt more than you'd gain with "controlled" loft or float or whatever you want to call it.
Even if we're talking a solid lifter, you'd have to make compromises on the closing ramp to avoid bounce off the seat, which would hurt more than you'd gain with "controlled" loft or float or whatever you want to call it.
Some of us listen to folks who actually know what they are talking about, like Daren.
06-07-2011, 06:49 PM
#43
wrong about being on different wavelengths? I'm not disagreeing with everything he said, but nobody has addressed the issues I've brought up. Still wanting to hear from the experts what happens when you float (*hint* unload) a hydraulic lifter, especially these "trick" instances where you're running them off the bottom 
Care to share who does the clips in your lifters?
Care to share who does the clips in your lifters?
06-07-2011, 06:51 PM
#44
those are flat head engines you are refering to...no overhead valves to smash into the pistons. or pushrods, or rocker arms in the equation. and its all related to running the perfect rpm, because we've pulled our briggs motors down and seen witness marks where the valves hit the head from turning them a little too hard. imagine if you shifted just a 'little too high' in an overhead valve motor with controlled valve float...it would be a disaster. not saying its impossible. just saying its nowhere near the same thing you or i have dealt with.
06-07-2011, 08:23 PM
#46
if you want to loft a hydraulic valvetrain you have to run it off the top with lash, otherwise when you unload the lifter it pumps up and hangs the valve. Or you just run them off the bottom with "lash" without float with a ton of pressure so they can't pump up at all. Depends on what the valving is in the lifter, what the tolerances are, and what you can modify on them and stay in the rules. Renegade guys have spring pressure limitations, guys were running 400+ lbs on the seat and 900 lbs open on OEM replacement lifters. Still doesn't matter, if you unload the lifter it pumps up unless you've modified it otherwise. In that case can it still be called a hydraulic lifter?
06-08-2011, 03:24 AM
#47
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if you want to loft a hydraulic valvetrain you have to run it off the top with lash, otherwise when you unload the lifter it pumps up and hangs the valve. Or you just run them off the bottom with "lash" without float with a ton of pressure so they can't pump up at all. be called a hydraulic lifter?
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Depends on what the valving is in the lifter, what the tolerances are, and what you can modify on them and stay in the rules. Renegade guys have spring pressure limitations, guys were running 400+ lbs on the seat and 900 lbs open on OEM replacement lifters. Still doesn't matter, if you unload the lifter it pumps up unless you've modified it otherwise. In that case can it still
I'm fairly sure we're not Talking about "lofting" a valve an extra .150", but maybe .050"-.070". Any more, and I would imagine there's too great of a chance of the pushrod not finding it's home when things come back together.
I've not built a stocker myself, but a guy I work/went to school with has. '93 Camaro with an ls1 he's setting up for B F/IA
06-08-2011, 04:44 AM
#49
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he did post up a link to some comp "lofter" grinds once tho..
06-08-2011, 10:14 AM
#50
wrong about being on different wavelengths? I'm not disagreeing with everything he said, but nobody has addressed the issues I've brought up. Still wanting to hear from the experts what happens when you float (*hint* unload) a hydraulic lifter, especially these "trick" instances where you're running them off the bottom
Sorry to not really answer any questions on this, but any answer that I might give would be my opinion of how things work. There are a lot of smarter people than me that can probably give a much better answer.
I will say that in a motor that doesn't have a rules restriction on the cam and valvetrain I would do things differently.
And yes, the motor that I pulled from gump last year shows signs of piston to valve contact.
Care to share who does the clips in your lifters?
06-08-2011, 11:58 AM
#51
I covered this topic in a previous post. Basically, as long as the lifter has some hydraulic lash adjustment to it (like I said, in the .020"-.030" range) it is still, therefore, a "hydraulic" lifter.
I'm fairly sure we're not Talking about "lofting" a valve an extra .150", but maybe .050"-.070". Any more, and I would imagine there's too great of a chance of the pushrod not finding it's home when things come back together.
I've not built a stocker myself, but a guy I work/went to school with has. '93 Camaro with an ls1 he's setting up for B F/IA
I'm fairly sure we're not Talking about "lofting" a valve an extra .150", but maybe .050"-.070". Any more, and I would imagine there's too great of a chance of the pushrod not finding it's home when things come back together.
I've not built a stocker myself, but a guy I work/went to school with has. '93 Camaro with an ls1 he's setting up for B F/IA
When you unload the lifter it pumps up and hangs the valve.
06-08-2011, 03:00 PM
#53
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I understand what you're saying. I'm not 100% sure on the lash adjustments on a stocker, but they could very well not be preloaded at all, which could eleviate the concern of a lifter pumping up.
12-13-2011, 02:08 PM
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I realize this is an older thread, but I wanted to comment on a couple of things. First, I am not "lofting" my lifters with the camshaft I run. I don't know about the others, but I don't think they are since I don't feel there is an advantage.
There is also a lot more ET to be found in these cars that isn't limited to the engine. I have found a ton of ET paying attention to suspension details, how the car leaves, and how it lands. I am generally in the 4.11's to 4.12's at the 330' in my go fast mode without icing the car. My 60' times are pretty good at 1.32, but I don't trust them as much because the wheels can be carried past the beams.
I feel that I have found quite a bit also in the tune. There are several events that I will address throughout the run. Most of the theories that I have on these events have seemed to work. Of course, some of them don't and many surprise.
Kyle Ratcliff
4121 C/SA
1998 LT1 Firebird
There is also a lot more ET to be found in these cars that isn't limited to the engine. I have found a ton of ET paying attention to suspension details, how the car leaves, and how it lands. I am generally in the 4.11's to 4.12's at the 330' in my go fast mode without icing the car. My 60' times are pretty good at 1.32, but I don't trust them as much because the wheels can be carried past the beams.
I feel that I have found quite a bit also in the tune. There are several events that I will address throughout the run. Most of the theories that I have on these events have seemed to work. Of course, some of them don't and many surprise.
Kyle Ratcliff
4121 C/SA
1998 LT1 Firebird
12-13-2011, 08:15 PM
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12-13-2011, 08:41 PM
#59
They hold an lt engine based shootout every year in bowling green, ky. From what I hear its a blast and I plan on making it there this upcoming year.
ltxshootout.com has last years results and tech rules, ltxtech.com has the best threads on it. Come out and have fun with everyone!
ltxshootout.com has last years results and tech rules, ltxtech.com has the best threads on it. Come out and have fun with everyone!
12-13-2011, 08:42 PM
#60
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The annual LTX Shootout for LT1/4 powered vehicles. It gets great coverage in the national magazine GM HighTech Performance. Here's a link with the latest article:
https://ls1tech.com/forums/lt1-lt4-m...ths-gmhtp.html