trilkb

iTrader: (4)

Well like the title says...

In the next couple days (once I get my mind and parts straight) ill be buying scorpion 1.7 rockers/springs/guideplates/pushrods and long tube headers.

I know from fbodybrian's post I have most of the part numbers (what he used)

ARP-134-7103 arp 7/16 studs
TFS-30400623 guide plates
PAC1212x Springs
SCP-1026 Scorpion 1.7 rockers

Im also pretty sure he used stock length pushrods. Obviously a measuring pushrod tool is preferred, but stock have been proven to work fine. So I will order stock length trickflow chromoly pushrods as well. I already have tims valve spring tool from my last spring swap.

Question is....Are the pac1212x a good spring? What about the comp 918? Others? I plan to either supercharge or cam the car, and id like to buy springs once. Is there a spring out there that would be better suited for a lt4 hotcam with 1.7 rockers?

I beleive the lt4 hotcam is rated at .525 w/1.6 rockers right? So .557 with 1.7?

If someone could make a spring suggestion that would be great.

Also, do guideplates require a longer pushrod? to be it seems like they would lift the rocker stud up XX thousandths of an inch and then the base of the rocker would be higher as well? perhaps Im overthinking it?

Has anyone run a 92-96 corvette with header studs rather then bolts? Im curious if it would make the install any easier...

A cam or supercharger is down the road, I think this summer ill enjoy the long tubes and rockers, should net around 35-40RWHP. Is it sad I look forward to changing 18 springs more then 2 exhaust headers?! This will be my third time installing long tubes on a lt1, first time on a vette though, all I know is the last two installs SUCKED and I doubt this one will be any different.

fbody_brian

For me, the stock pushrod length worked out great. The mark on the tip of the valve is pretty much dead center. YMMV!
The PAC1212x worked great with the stock cam and 1.7s.
That being said, I have some observations to share.

I had to set the valve lash to 1/4 turn past 0 lash. The rockers are REALLY close to the base of the rocker stud with this setup. Unknown to me I had a lifter that was collapsed and I had adjusted the preload, after that I wore some metal off the bottom of the rocker. There is No room for error with the geometry of my setup.
If the pushrod were to be too long, I would have no room to go shorter without milling the bosses down.
Because the geometry, the pushrod sits all the way at the bottom of the guideplate slot, you have to remove material from the guideplate or you will eat your pushrods up in short order. It was not difficult but it was time consuming with a dremel, being very careful not to hit the sides.

I swapped in a cam, with the 1.7s the lift is .534/.544, which I hoped would be within the ability of the pac1212x springs as they are rated at .550 lift. They could not control the valvetrain at 6000rpm. I got float and ate up my valve stem seals. Live and learn.

I swapped back to the stock rockers until I can get some better springs, or I may just go for 1.6 rockers, because of the geometry being on the ragged edge.

All that being said, The difference between the stock rockers and the 1.7s are noticeable. The throttle response improves across the board, and I noticed the loss of it when going back to stock for the time being. especially in the midrange.

trilkb

iTrader: (4)

Thanks for the info, I was going to pm you to see how it was holding up.

So what's the fix to run the 1.7s and not worry about trimming guideplates? Is there one?

Should I be looking at a different parts list to run the 1.7s? I forget if they are nsa or sa, I bought a set of scorpions for my old trans am and didn't use guide plates. Do the 1.7s need them?

BALLSS

since you asked....

"I" would get 1:6 RR vs 1:7. You mention "cam or super charger (you will want a cam either way)" down the road. What ever that cam is will likely want 1:6 RR vs 1:7

Scorpian..budget rocker. "I" would get Comp Pro Mags.

your next motor mods likely will be heads and cam so you can re-use the 1:6 RR and 7/16" studs

Guide plates....I use the ISKY adjustable for 3/8" PR. they allow you to adjust each RR L-R on the valve tip dead nuts vs 1 piece guide plates

springs...your cam will dictate a spring open & seat pressure rating. I am not a fan of bee hive springs vs double springs but many do use the PAC or Comp. Understand springs are a wear item...the more cam you get the shorter their life. They may be fine for your current use but when you get a bigger cam you likely will need new springs. I went with the Lunati 73925K5 kit set up at 1.780 installed height. That gives me 155-160 on the seat and 380 lbs open. This may be to much for your current cam. Most aftermarket springs spec the installed height at 1.800". You need to have your spring pockets machined down to accommodate a 1.800" spring OR your seat & open pressure will be more if installed on stock heads only allowing around 1.750 height. Some stock heads only allow 1.71xx so +.050 retainers and thinner locators are needed. Moving off the "I would" topic but understand valve train needs to be set up right for the spring & cam you have along with "geometry" (PR length & guide plate alignment)

Your basically stock motor will be OK with something like a Pac or Comp 918 spring set up slightly under 1.800"

A more "drop in" spring would be the Crane 10308-1 kit (stock installed height) or on a budget Alex springs have good reports. Again you will likely change springs based on your future cam

whatever spring you get, replace the valve stem seals

for stock motors that have not had head or block decking the 7.200" long PR will work. TrickFlo Chromalloy 3/8" with .080 thick wall PR are good

fbody_brian

^^^This

1.7s are fantastic with the stock cam, but if you're going to change the cam later go with 1.6s.

trilkb

iTrader: (4)

Wow, I totally forgot about the cam dictating the seat pressure and all of that. Been to long since Ive done any engine work.

Honestly I REALLY want to go the supercharger route. Half of my last build I butchered on my own, but the .606/.603 lift cam really didnt help when the heads/intake/tb were all stock haha. So I think the stock cam is going to stay in it most likely. Ive been looking for used supercharger kits for almost a year now, not that hard...but looking. Something around the lt4 hotcam or the Ai cam is the biggest id go. I want zero idle or drivability issues. This car will retain its ice cold a/c and needs to be able to be daily driven in the spring/summer/fall rain or shine. Id love to go with a turbo, but a supercharger can be tame when you want it to be as well.

I do really want to go with the 1.7's, I would like all the HP on the table for rockers/long tubes because I dont plan to do a cam anytime soon, or any other mods. I just want a bit more power out of it for now.

I swear I was running a self aligning scorpion rocker arm too, I cant seem to find any right now? Maybe I just F-d up and should've been using guideplates.

I was running 1.6 comp ultra pro mags on my old trans am, and patriot gold springs. I switched to scorpion 1.5's to get the lift back down to 568/565 which is more what a stock head lt1 needs. I didn't feel the scorpions were a inferior product.

So will adjustable guideplates help with the problem? And yea valve seals will be done, to easy not to do them.

Vicious95Z28

iTrader: (1)

I can understand wanting a mild cam but I think you'd be best to stay with a 1.6 rocker and talk to Lloyd about a mild cam for your application. If you're serious about doing a blower Lloyd can hook you up with something that will sound nice, work great and best of all he'll point you in the right direction for the rest of your parts list.
My personal feeling is that you're going to end up with more of a hassle by doing 1.7 rockers than if you just did a good cam upgrade.
Besides all that, good cams are just a great bang for the buck. They do something special for the character and attitude of the car. My .02¢

trilkb

iTrader: (4)

I'm pretty much dead set on 1.7s right now.

fbody_brian

I think you'll be really happy with the increase of power with 1.7s and long tubes.
Great SOTP difference, especially in the mid-upper rpms.


You will absolutely need guideplates and hardened pushrods, as all the 1.7s are NSA rockers.

If you aren't going over about .520 lift, which is what you are going to have with the stock cam (actually .510/.521) then the PAC1212x are a good spring, and you can use your stock locks and retainers. I find it strange though that they list the springs as max lift .550. You would think that that is max safe lift before coil bind. If you take the numbers installed height 1.750 - lift of .521 = 1.229 - coil bind 1.180 = .049.
So with these springs you'll have .049 to coil bind. I think I'm doing that right, not sure, because if you do the numbers with .550 lift you only have .020 safety margin. that's not much at all.

I see a lot of people recommend the ALEX Parts springs, but I have yet to see them available at any time over the last couple of years.
If I could go back and do it again I'd get a spring with a little more room to grow, the PAC1218 or something else, of course cost goes up a bunch because now you're getting into new retainers and possibly offset locks, etc.

ahritchie

iTrader: (1)

There's plenty of other cams that offer good drivability other than the hot cam that take advantage of the last 20 years of camshaft lobe tech advancements. I'd get a custom cam for a blower setup, or here's a better option similar to the hot cam, I had this when I was cam only and it's very streetable: Lunati voodoo 60121

Advertised Duration (Int/Exh): 270/278
Duration @ .050 (Int/Exh): 221/229
Gross Valve Lift (Int/Exh): .515/.530
LSA/ICL: 112/106
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1800-5800

trilkb

iTrader: (4)

Yea I don't know what to think about the Pac 1212x. The crane kit suggested didn't look bad but I didn't see bind numbers listed.

The more I think about it, the more I'm fairly certain the stock cam will stay in the car. If I did heads and cam, I'd be stupid not to rip the motor out and rebuild it, if not make a 383. So 200$ set of rocker arms would be pennies compared to the rest. Blower cam makes me laugh, it will just get supercharged, not both.

I have so many other projects going on the supercharger probably won't realistically happen for a while.

I pm'd lt1 xjs to see what his setup is because I remember hearing he's running 1.7s.

Thanks for all the input so far!

BALLSS

you may find a few that agree with your choice but as you see most in this thread advise going with a 1:6 RR

good luck

ahritchie

iTrader: (1)

You say that now, but when the modding starts, things can and usually do quickly snowball ....the 15-20 HP (maybe) you gain with 1.7 RR and springs will just be a tease making you want to add some more HP.... You'll need a tune to get the full benefits after of each round of mods as well.

trilkb

iTrader: (4)

Lol that's true, but I've wanted a v8 with forced induction since my vr4 and rt/tt. It looks like that crane valve spring kit can handle a moderate cam too. So if that day comes I'll sell my 1.7s and get 1.6s, and the springs may be ok, if not I'll do springs again.

I've wasted more then 500$ (rockers and springs) in this hobby haha, if I was worried about that I'd have never sold my first gta trans am. If I run the 1.7s and stock cam for 2 years I got my money worth in my eyes.

The idea of a 100 wet shot crossed my mind too if I need a little more. I want 12.5-13 out of this car for now, closer to 12.5, but I want reliable too. Sure aftermarket cams are reliable but so is the stock one. I think the long tubes and rockers can get me there. I don't have that much interest in doing a cam swap or the supercharger. Plus my fz1 is my real adrenaline toy. I just feel the c4 needs a bit more.

I guess "first round" might've been the wrong wording haha

Fly on the wall

Is your vette an auto? If so, first on your list should be getting rid of those 2.59s, and replacing them with at least 3.55s. Putting headers on a LT1 C4 isn't that bad. Although when I put headers on mine I ripped out the emissions junk and didn't have to worry about re-connecting the air tubes. I do believe the passenger side air tube will give you problems when you try and re-attach it to the header. The bung on top of the header, for my application, was at a different angle and the air tube would not screw on.

trilkb

iTrader: (4)

No it's a 6 speed, factory 3.45 rear end.

I haven't heard any complaints with the obx headers I'm going to use. Guy just put them on over at corvette forum and sad no surprises on his 96 6 speed. Mines a 1995. I wouldn't be looking for 12s with headers and rockers out of an auto lol

Vicious95Z28

iTrader: (1)

At Atleast 3300# a 3.45 gear isn't all that impressive. With a blower, it's a manageable gear but n/a it sucks. 90% are giving sound advice on cams, rocker arms, etc. Basically trying to prepare a decent setup. You seem set on doing it your own way.

trilkb

iTrader: (4)

Haha, well not to sound like an ******* but it's my car and my money. I appreciate the info I've been given but at this point who says it won't stay a bolt on only car? I'd like a supercharger but who knows if it will really happen as well.

I see results from 1.7 over 1.6 and people have ran them without issue. All I'm trying to do is get the correct parts to buy....springs mostly. Like I said I forgot an aftermarket cam needs springs spec'd to it as far as seat and open psi.

Not trying to be an *** or tell people not to give me info. I'm not generally like that, but telling me to run 1.6 rockers isn't helping me run 1.7s lol. If it's such a terrible and horrible thing to do I'll learn. I don't know if I made it sound like it's definitely, certainly, positively going to get a cam or supercharger, but that's not the case. I also don't see why 1.6 would be better then 1.7 if I did get a supercharger?

NewOrleansLT1

I run 1.7rr... Just have to get springs that works.. A rule of thumb I use is if 1.6 gives you .530 lift then 1.7 gives you .560 lift.. The bigger the rocker the bigger the cam acts too.. 1.6 to 1.7 makes the cam act like its about 2 degrees bigger.. FYI I called comp and specd my cam around the 1.7 rocker..

trilkb

iTrader: (4)

Are you running the scorpions? Which guideplates are you using?

I guess I need to find a spring that will work with stock hardware.

Btw a more reliable way of finding lift is to take the known lift, divide by the rocker ratio and multiply by the new... 530÷1.6× 1.7= 563. That's how I do it anyway.