I just want to know if I will see noticeable improvement if I put 1.6 roller rocker on my stock L98. Should I save money to buy a new cam instead?

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89 L98 GTA
- Custom made air induction
- Ported plennum
- MAF sreen removed
- Headman Hedders
- Dynomax 3" catback
- Ultra Flow weld muffler
- TH700-R4 with vette servo and Superior shift kit
- Mobil 1 Synthetic Oil
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Soon: Spohn SFC

 

You'll notice a difference. Say your lift is .425 with 1.5 rockers, It will be .453 with the 1.6 rockers. It won't do anything for the duration though, and that's where a new cam will help. Plus, goin to full roller fulcrum rockers will decrease the friction in your valvetrain.

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'88 IROC TPI 355, '69 truck 4-bolt, fully balanced, 9.75:1 compression, fully ported '70 truck heads(for now), Harland Sharp 1.6 Roller Rockers, Comp Cams CS 252AH-12, ported '86 TPI converted to speed density, Crane AFPR, Flowmaster 3in. exhaust, Edelbrock TES headers, all emissions equipment is still intact, plan on burning my own chips, many more mods and parts on the way as time and money permits =(
Best E.T. with TBI 305: 16.11 @ 82mph
Haven't been to track with new motor
If you have any questions on converting from TBI to TPI email me at jdkchevy70@yahoo.com
In memory of Dale Earnhardt, I'll miss cheering for that black #3 on raceday!!!

 

Also, effectively, the 1.6 rockers increase the duration of the cam a tad.

If you go this route, I would recommend the Comp Cams 1.6 roller tip rocker arms. They fit under the stock center bolt valve covers and cost about $130US.

I'd like to ask you about your vette servo. What has it done for you? I know that this takes us outside of this topic area.
Since I have a 2400rpm converter, I've lost my hard shifts. I'd like to get them back.



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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 2400 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, 24#/hr SVO injectors, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(58psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.39sec @ 107.21mph
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph

 

To anser to your question Doc, I canot tell you what te vette servo alone realy do because it was installed with the shift kit. But I can tell you the shift kit and the vette servo **** realy hard. The tires skweak when the 2nd shift and the 3rd shift hard at 5200rpm.

Hope it help.

 

I have Crane 1:6 rockers on my car with stock cam. If I were you I would go ahead and do the rockers now. The stock rockers are not very good compared to full roller. Then you can always do the cam later. I asked a question awile back about high ratio rockers vs high lift cam and was told it is better to get the lift with the higher ratio rockers that is why you see 1:7 in the new vettes and I think but I may be wrong 1:8 in the ZO6 vette. One question though how much lift is safe with pressed in studs?

 

If I'm not mistaking, I believe the Corvette servo allows you to make full throttle shifts from 3rd to 4th. Without it, the car just stays in 3rd until it tops out. But where exactly can you use this fucntion? IN GERMANY!!! LOL!

 

Im interested in the 1.6 rollers too. Should I get new pushrods and springs at the same time? How hard are these to install? How is the engine turned to adjust the rockers once they are in? Thanks, Doug

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'91 Z28 - 50,000 miles. All power options leather. 350 TPI:
K&N; Fastchip; Airfoil; Custom 'Ram-Air'; SLP Headers; Slp Runners; Borla Catback 50% open; Dual factory Cats; Poweraid TB spacer; March underdrive pulleys; Accel Extreme 9000 wires, Accel coil; Hypertech rotor & cap; NGK platinum plugs; manual fan switch; TB coolant bypass; Pirelli P7000 Z245/50/R16 all season tires; Energy suspention motor mounts; smog pump delete.
S Cobra Radar Detector; Z28 SS Floormats

 

I would change springs and pushrods also. When I put my rockers on my car had only 30,000 miles on it and found out that stock springs at that time only had around 40lbs seat pressure. I have the Crane rockers and the stock pushrods do not work well with them because of the little ball on pushrod.It is a little time consuming and you will need a spring compressor I had to use both types.

 

Hey guys, I gotta Q 4U. How many of you are running the pressed in stock studs and how many have screw in studs? I understood that you had to upgrade to screw in studs? Am I mistaken? Thanks..

 

I have the stock L98 heads on my car with pressed in studs but even with the rockers the lift is only around .460 exhaust. I think as you get closer to .500 it is time to change to screw in studs. I have heard some guys pull the studs with less lift and some with more. I feel safe where I am now. But I do wish my car did come with screw in studs though.

 

You'll probably need the self aligning rockers which are a little more expensive.

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Fast as a shark~~~~~~~~~~~~~~~~~ SAVE NAPSTER!!!

 

If you want to install new push rods and new springs, you will have to pull your heads off to do that, for the springs at least. If you are pulling your heads off, you're going to have to pull your intake off and thus you are about 90% of the way to doing a cam swap, so spend the extra $200 or so and get a new cam. When you do a cam swap, you should just go ahead and put on new springs, retainers, valve seals and a timing chain. IMO, its a waste of money to just buy new rockers when you can get a new cam for the same price. My 1.52 self aligning roller rockers from Comp Cams cost me $200, my LT4 HOT Cam was only $165.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

I agree with Dan, because that is exactly what happened to me. I already have the aftermarket intake pieces in my room, and bought a set of Holley alum heads for X'mas. Of course, with the intake&heads off the car, we figured that we might as well go for a push rod, cam, timing set, etc... upgrade. The costs will build up a bit, but it will be worth the efforts in the end considering what's involved.

 

I installed new rockers,springs,pushrods and valve seals with the heads on the car.

 

New rockers, pushrods, lifters, springs, seals, retainers, cam, timing chain, all done with the heads still on the car.

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

Regarding press-in rocker studs, I'm running .495/.502 lift with press-in studs, no problems yet. Anyone changing their cam should go with hardened or chromemoly pushrods - I found bent OE pushrods with both the LT4 production cam and my Comp cam. Trick Flow pushrods are ~$80 at Summit.

 

FYI,

Valve springs can be R+R'd with the heads on the car by supplying high pressure air to the cylinder through the spark plug hole (with an air fitting adapter) to prevent valve droppage. I've heard some people say they have done it by putting rope into the cylinder through the spark plug hole or by just turning the engine and getting the piston all the way up for the cylinder you are working on but I would use the air pressure method. I've used it many times and never had a valve drop .

Just incase you guys wanted to know................

 

...and if you're careful about cleaning up after yourself, you can pull the rocker studs and tap for screwed studs with the heads still installed.

Just make sure you clean all the oil out of the heads, remove all the rockers and push rods, plug all the oil drainback and push rod holes, and use a magnet to retrieve all the chips from tapping. If you use screwed studs without the hex collar on the base (the type that are installed with jamb nuts) you won't need to machine the stud bosses for depth and can retain the stock valve train geometry. You can even use an old towel or other cloth with a single hole cut in it to surround the one stud you are tapping. The cloth will prevent any debris from falling into the head drainbacks. You'll still have to clean up thoroughly, but it can be done in a few hours by this method.

For about $15.00 for a screwed stud kit and a 7/16-14 tap, you're screwed. Been there more than once...

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Later,
Vader
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"What a Day..."
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