LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Little Update

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Old Jan 19, 2012 | 12:48 PM
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Default Little Update

Cylinder head freshen is in progress, should be ready tomorrow or monday at the latest to pick up from the machine shop. Doing a cleanup mill on them, R&R valve guides and touching up the valve job.

Intake is a Holley Stealth Ram, opened to a 12367777 gasket at the head, opened as large at the plenum that will still allow a sealing surface. Has a 1" thick aluminum direct port plate that extends the runners just a little bit to help out in the 6500-7500 range. It has .018 jets in it right now for tuning.

Motor is otherwise back together, cam is degreed in, it's a 267/272@.050 .695/.695 solid roller stick on a 110LSA in at 106 for a 107 running ICL. The exhaust lobe is somewhat slow, however I still think the motor will like a 1.5 rocker there on E85.

Also I've taken some material out of the pinch on the heads, they were ~2.15" CSA and I've opened it to a ~2.40" CSA. Heads now pour closer to 218cc with a few cc variance.

Valvesprings will be another set of PAC beehives. still waiting to hear back on the cause of failure on the other set (I still think it was a spring flaw). Pressures are about 205/490.

Lifters are a modified set of GM LS7s, my old comp 875s had over 30k miles on them so it was time for them to retire

Also put Hy-gard in the TH400 to tighten the converter up a bit. I was seeing 5700 rpm flash with my old 244 degree cam, lt4 intake and conservative timing, I'd like it to go 5200 or so with this motor setup.

Still running E85 here in WA, they do go E70 in the winter so I'll need to buy E85 bulk in the fall I'm limited by injector size right now to about 750 hp with nitrous (60 psi rail pressure) so that will keep me with the .018 jets for awhile unless I crank up the rail pressure.

Pictures to come probably this weekend
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Old Jan 19, 2012 | 12:59 PM
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Sounds good. Only one thing is confusing me. Why are you modifying hydraulic roller lifters to work with a solid roller cam?
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Old Jan 19, 2012 | 01:24 PM
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Why dont you run a Dedicated fuel system for the nitrous so you have more room in both areas? Plus low pressure nitrous fuel systems seem to be easier to dial in.
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Old Jan 19, 2012 | 01:42 PM
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I run dry nitrous, I have plenty of fuel pump and lines, just limited by injectors (60 lbs/hr).

05HD - Because there's no reason to run a solid roller lifter in this application! Why run a 700 dollar set of lifters when a 150 dollar modded set will work just as well. They end up running like a solid lifter with hydraulic lash (CUSHIONED) and are easier on parts. Most of the good hydraulic lobes are aggressive with less lobe lift, meant for below 7000 rpm useage. I need more lift to make power above 7000, that's why the solid roller cam.
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Old Jan 19, 2012 | 04:32 PM
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Mind PMing the lobe specs to me? Must be pretty tame since that seems like fairly light spring pressures...you're not worried about losing control of the valves with that much lift above 7k?

How well did that 7777 gasket match your AFRs? I got much closer with the beastly felpro 1206 race gasket. Its an SBC gasket though, so have to punch your own holes (oh noes).

Can't wait to see your new combo together. I'm planning to drop my block off next week to have the pistons flycut .
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Old Jan 19, 2012 | 05:37 PM
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They're street friendly but not lazy, the valvetrain is light! The mustang guys are taking these springs to 8500 with OEM liters off the bottom. The lift is there but the nose profile is smooth.
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Old Jan 19, 2012 | 05:44 PM
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Originally Posted by Wicked94Z
They're street friendly but not lazy, the valvetrain is light! The mustang guys are taking these springs to 8500 with OEM liters off the bottom. The lift is there but the nose profile is smooth.
What valves are you using?
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Old Jan 19, 2012 | 06:34 PM
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700 lift with 1.5s ?

I was afraid of pushing the lifter too far with loves like that. Hence why I specd my **** with 1.7s

Just theory though, haven't know anyone to try it. I would keep an eye on the lifters for wear though
The amount of time they are lined up with the oiling holes all be reduced significantly with that much lobe lift.
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Old Jan 20, 2012 | 01:46 PM
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lobe lift is .430ish. It's no different than .360 lobe on a big base circle, the only difference is how far the lifter sits on the base circle... I'm on just short of a 1.000" bc, doesn't drop the lifter too far down

Valves are 2.08/1.60 manleys 5/16" stem with some lightening work.
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Old Jan 20, 2012 | 03:01 PM
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Ahh small base circle. Sounds like it will be rowdy !
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Old Jan 21, 2012 | 11:29 PM
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Glad to hear everything is back together and also to see you posting here again. Now get back to work on your "opti-eliminator"
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Old Jan 22, 2012 | 09:05 AM
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Originally Posted by gregrob
Ahh small base circle. Sounds like it will be rowdy !
I'll bet that cam talks to him...
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Old Jan 22, 2012 | 10:00 PM
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Keep us updated.
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Old Jan 22, 2012 | 11:15 PM
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I wouldn't be wanting to run a single spring in an application like yours. I learned the hard way once. Sounds like you have too
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Old Jan 23, 2012 | 08:43 AM
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[QUOTE=Puck;15860226]Mind PMing the lobe specs to me? Must be pretty tame since that seems like fairly light spring pressures...you're not worried about losing control of the valves with that much lift above 7k?
QUOTE]

i only run #220 at the seat on my SR app and im reving ~8000+.......controls it just fine with light parts and proper geometry....


and glad to see you back in the game steve
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Old Jan 23, 2012 | 12:32 PM
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Originally Posted by Puck
Mind PMing the lobe specs to me? Must be pretty tame since that seems like fairly light spring pressures...you're not worried about losing control of the valves with that much lift above 7k?

How well did that 7777 gasket match your AFRs? I got much closer with the beastly felpro 1206 race gasket. Its an SBC gasket though, so have to punch your own holes (oh noes).

Can't wait to see your new combo together. I'm planning to drop my block off next week to have the pistons flycut .
my heads are matched to the 7777 gasket , its just a 1207 height and 1205 width
. it's 2.85 CSA at the port opening.

[QUOTE=quik95lt1;15873947]
Originally Posted by Puck
Mind PMing the lobe specs to me? Must be pretty tame since that seems like fairly light spring pressures...you're not worried about losing control of the valves with that much lift above 7k?
QUOTE]

i only run #220 at the seat on my SR app and im reving ~8000+.......controls it just fine with light parts and proper geometry....


and glad to see you back in the game steve
thanks bud, yea im probably 40 grams lighter at the valve than you with this setup, milder lobe and i can get away with 150lbs less over the nose
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Old Jan 23, 2012 | 01:19 PM
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Originally Posted by quik95lt1
i only run #220 at the seat on my SR app and im reving ~8000+.......controls it just fine with light parts and proper geometry....
I was thinking more about the open pressure being 490, but with his lightweight valvetrain and milder lobe I guess it makes sense .

Originally Posted by Wicked94Z
my heads are matched to the 7777 gasket , its just a 1207 height and 1205 width
. it's 2.85 CSA at the port opening.

thanks bud, yea im probably 40 grams lighter at the valve than you with this setup, milder lobe and i can get away with 150lbs less over the nose
With your light valvetrain and little tricks I'm sure you can make it work - I'm at 260# closed 730# open but my lobes are pretty nasty right off the base. I'm just hoping high spring pressure + shaft mounts I will keep everything in check at 7500+.

Keep us posted .
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Old Jan 23, 2012 | 01:49 PM
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I've been seeing more pac spring failures on the boards, and this just happened to me this weekend. I changed out the last set at 20k miles with no failure, and this set only had 6k on it. New springs should be here this upcoming weekend and they are not pac's.



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Old Jan 23, 2012 | 01:55 PM
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**** behives where they breathe.
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Old Jan 23, 2012 | 01:59 PM
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excellent you pull the head yet? i dropped the valve but it stayed intact, it was a flo valve at that... couldn't believe it held together.
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