Need input from the valve train guru's

1545 Views 7 Replies 4 Participants Last post by Viper, Mar 11, 2013

E&A's T/A

Discussion Starter · Mar 7, 2013

I've been wanting to do some minor upgrading from stock to the valve train on my 94 T/A with 126k miles. Really the only mod it has now is long tubes and 3" ORY to a flowmaster and an LT4 knock module. Now I like to drive my car in town from light to light at the speed limit and continue getting around 18 mpg. When i added the headers it really seemed to move the power up and thats great when I'm on the interstate and want to have a little fun so I want to keep that but also get that power back for the light to light driving. At this point i'm on a tight budget so I'm not looking to do a cam swap. NOW I have read till I cant see straight about cams and there design and I guess I'm not one of those people who can look at cams specs and tell what characteristics a certain cam will have and where it will make power at so thats why I am asking this question. If I added 1.6 rr to the exhaust and 1.5 rr to the intake would that gain me where i want it to? From off idle to 2500 rpm range without hurting the higher rpm to much?

I know what I am wanting seems a little odd because a lot of you want the preformance to be at high rpm for the track but I am looking for it to have that instant power and have the consistant gain through the rpm range if thats possible. Any thoughts on what the different ratio rockers might do I'd be glad to hear.

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Viper

· #2 · Mar 8, 2013

Most all modifications will make more of a difference in mid to high rpm. Roller rocker arms will not reduce low rpm 0-2500 rpm power nor will idle change or gas mileage. From 4500Rpm up is where the additional 10-15hp from Lt4 springs and 1.6 rockers arms will make a difference. If you intend to add a cam in the future Alex's parts springs Kit will allow both the rocker arms and later on a cam.

Stamped Steel vs. Roller Rockers - Test Data Please! • Speed Talk

Valve springs for light mods - LS1TECH

LT1 VALVE SPRING KIT Includes: SPRINGS, RETAINERS, LOCKS & CUPS. - Alex's Parts Sales

Beehive Valve springs - Page 3 - Chevrolet Impala SS Forum : Chevy Impala SS Forums

Higher Ratio Rocker Arms

LT1 - High Mileage - Reliable Build, How-To - GM High-Tech Performance Magazine

Camshaft Variables Basics - Tech Article - Chevy High Performance Magazine

Dyno - Tested Camsheft Thoery - Car Craft Magazine

Chevy Small Block Cam - Super Chevy Magazine

Camshaft Lobe Separation Angle Performance Test - Chevy High Performance Magazine

Headers catback and free flowing intake help mileage and performance up to 2500RPM.
Gears and stall convertor help the car accelerate quicker but mpg declines.
Suggest a K&N air Filter or Home made cold air intake and an airfoil add the 1.6 Rockers and springs get a peformance mail order tune.

Intercooler Pipe Fabrication - Silicone Intake Systems Auto Parts

Free Mods
http://www.ls1lt1.com/forum/lt1-|-lt4-|-l99-engine-tech/809-lt1-free-mods.html

Mod Dyno Results
WS6.COM LT1 Trans Am

Rocker Arms 101 - Everything You Need To Know - Vette Magazine

Adding Power Using Rocker Arm Ratios

Kennedys DynoTune- Valve Spring Tech Tips

Hydraulic Roller Cams - Car Craft Magazine

Cam Velocity-Advantage Mopar - Mopar Muscle Magazine

Camshaft Lobe Phasing - Tech Article - Chevy High Performance Magazine

Nitrous Cam 101: Dyno Testing Four COMP Cams... - LSX TV Forums

GrumpysPerformance.com • View topic - sellecting valve springs, and setting up the valve train

Weight reduction improves power to weight ratio Force= mass *velocity and mpg

Weight Reduction 93-02 - Club F-Body Mexico

4th Gen F-Body Weights Page

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E&A's T/A

Discussion Starter · #3 · Mar 8, 2013

Viper thats some great info. Thanks for all that I've got some more reading to do. I kind of figured that anything I added would be helpfull in the higher rpms but I was interested in attempting to find something that would help the lower rpms as well. I guess if I want to keep that low end power I shouldn't mod the car at all but I'm def not putting the old stock manifolds back on. I like the headers much better. I'm certainly doing a spring change with the rockers no sense in risking a broke spring in an effort to save a little money.

Thanks again. Thats the kind of info I probably wouldnt have found on my own and why I only ask my many questions here

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Viper

· #4 · Mar 9, 2013 (Edited)

The only things that really add to bottom end are headers( that boosts rpm range higher), Larger Cubic inches either larger bore and/or stroke and added compression ratio through milling the heads (smaller chamber cc's) decking the block thinner head gasket or domed pistons. Lower gears multiply torque and make the engine rev quicker thus adding to low end feel as does a higher stall convertor through increased slippage before lock up at a higher rpm. A torque cam adds some torque but only to a point then no more torque added at lower rpms given changes in cam specifications. Lastly supercharging, Turbocharging, and Nitrous Oxide injection all add torque these are considered boosted engines non normally aspirated. Enjoy the reading.

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cardo0

· #5 · Mar 10, 2013

Do the springs also with 1.6 rockers.

I've been looking into this myself and looking at the stock LT1 spring #10206040 has coil bind at 1.26" and the stock cam with .459" lift with 1.5 rockers becomes .490" using 1.6 rockers. This puts u close to coil bind on the exhaust spring (1.78" open - 0.490" = 1.29"). Only 0.030" for margin. That's not enough unless u use a rev limiter and keep RPMs really low.

IMHO the intakes need the lift more than the exhaust. This may would better if u don't change the springs.:thumbsup:

Good luck,
cardo

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lt1-xjs

· #6 · Mar 10, 2013

I believe in a stable valve train. I'm running a 7/16 stud, guide plates, chromoly pushrods, 26918 beehives and 1.7 NSA rockers with the stock cam. After 3 ratios of rocker arm changes I've found that the 1.7's make the most power with the stock cam.

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E&A's T/A

Discussion Starter · #7 · Mar 11, 2013

Cardo that was kind of what I was getting at as far as mixing the ratios wheather it be 1.6s on the exhaust or 1.6 on the intake and if either way would really make a difference more toward the low end torque. Of course the more i put thought into this more I think I should really re-word this more to say immediate throttle response because the car will could smoke tires all day off the line but it seems to take more throttle to do that so maybe the two go together or maybe I should of started this thread a little differently but mine main goal was to get an idea if mixing ratios on a stock cam was at all feasible or is it a waste of time and money.
I am for sure going to change springs the cars got 130k on it now so I'm sure the springs are weak I am probably going with Alex's springs and the hardened push rods but am still undecided on rocker arm manufacaturers, but I am getting the impression mixing ratios on a stock cam isn't really worth it.

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Viper

· #8 · Mar 11, 2013

Better not to run the split ratio 1.5/1.6 or others on Lt1s the dynos I've seen this works better on older Generation sbc heads LT1's run better with all the same ratio.

Competition Cams , Lunati, and Scorpion Make good rocker arms. If Self aligning Rocker arms I'd Run Competion Cams. Lunatis are Made by our Board sponsor Holley Performance Group and are great quality. Scorpion makes Rocker arms for Howards cams, Isky Cams, and Summits house brand rocker arms besides their name brand rocker arms.

Scorpion rocker arms ratios you can tune the lift and duration added by various rocker arm ratios 1.37 to 1.77.

To run non self align rocker arms you have to add 7/16 Studs and Guide plates along with hardened push rods.

Various ratios
http://www.scorpioncheckout.com/SearchResults.asp?Cat=106

Are scorpion rocker arms good? - Corvette Forum

Bottom end torque when TQ adders are Combined leads to additional bottom end power vs tire life and lack of traction where suspension mods are needed. This is a mild 383 with the Cam I have for my 350 not the most HP but a blast to drive.

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