Can 1.6 roller rockers be used with a ZZ-9 Camshaft on an L98 TPI with stock heads? Does anyone have this set up? If so, what kind of idle characteristics do you have? Is it still a good idle? Do the pushrods clear the slot in the head? Will the ZZ-9 Springs have to be changed?

------------------
1988 GTA 5.7L Auto
355 ci. block, SLP Cold Air Intake w/ K&N, fully modified MAF Sensor, TPIS 52mm Throttle Body w/Air Foil, Throttle Body Bypass Hose, Fully Ported and Polished Plenum, Nikel-plated Ported SLP Siamesed Runners, Ported TPIS Big Mouth Intake Manifold, stock heads w/ 1.52 Comp Cams Self-aligning Roller Rockers, TPIS ZZ-9 Roller Camshaft, TPIS Valve Springs, Cloyes True Double Roller Timing Chain, TPIS Adjustable Fuel Pressure Regulator, Balanced Bosch 22 lb/hr Fuel Injectors, MSD 6AL, Taylor 10mm Wires, Bosch Platinum +4 Spark Plugs, MSD Blaster Coil, March Underdrive Pulleys, 6 3/4" Vibratech Streetdamper, TPIS Level 4 PROM, 160 T-stat, Low Temp. Fan Switch, Stock Distributor w/ Bronze Gear, SLP 1 3/4" Headers, Random Technologies High Flow Cat., Adjustable Borla Cat Back Exhaust, Level 10 PTS-3 700R4 Trans, B&M Holeshot 2400 Stall Converter, B&M Trans Cooler, TCI Aluminum Finned Trans Pan, Torque Converter Lock Up Switch, 3" Balanced Aluminum Driveshaft, 3.73 Richmond Gears, Auburn Pro-Series Differential, LPE Aluminum Differential Cover w/ Main Cap Preloads, BF Goodrich Drag Radials 255/50 R16, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Hotchkis Tie Rod Adjuster Sleeves, Bilstein Heavy Duty Shocks and Struts, 1LE Springs, Energy Suspension Polyeurethane Bushings, Global West Tubular Subframe Connectors, Global West Steering Box Brace, HP Motorsports 3 Point Strut Tower Brace

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

You will need new valve springs with the ZZ9 Cam anyway, even if you keep the 1.5 rockers. If you get 1.6 rockers, you are going to be running A LOT of lift, especilly on the exhaust side. IMO, when doing a cam swap, you might as well dissasemble the heads and get new springs, retainers, valve seals and clean up your valves.

------------------
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)

7.5" 10 Bolt with 3.42s soon to come!

 

You'll definitely need to have the heads machined to handle a cam like that with 1.6 rockers, like Dan said.

------------------
West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

You will need to have the heads machined even if you use 1.5's with that cam!!

 

I was once told by one of the tech guys at TPIS that my stock springs would work fine with that cam.I politely thanked him for his help and have never called them again.

------------------
92Z28
89GTA

 

Glad you asked that question because I went down that exact road last year.

I installed the ZZ9 in my 86 L98 Vette 355 CID and installed 1.6s. Bent a bunch of pushrods even though I checked for interference as best I could.

With the engine in the car it's really hard to watch the pushrod all the way through its entire stroke.

I later learned that the slots in the heads aren't elongated enough to clear all the pushrods and interference results at speed causes binding.

So, off with the heads, to the machine shop to have the slots elongated and while there I had the heads milled and tapped for guide plates and screw-in studs.

I installed the plates and studs myself - bought 'em cheaper from PAW than what the machine shop was going to charge. Problem solved.

With 1.6s on the exhaust you'll be lifting the valves over .550 so you'll need springs that can handle that kind of lift. You'll also need 120 lbs on the seat.

I degreed mine in per TPIS' specs (108) and with 1.5s all around it idled fine, and pulled 18 inches Hg of vacuum. With 1.6s on the intake and 1.5s on the exhaust idle remained just about the same as did vacuum.

When I went with 1.6s all around idle quality noticably degraded, but the car was still quite driveable. Mid-range was a bit stronger too.

The engine lost 2 Hg of vacuum, down to 16", but the brakes still worked without a hitch. The idle became noticable but not objectionable. It definitely let everyone know there was a cam in the engine at stop lights.

Hope this helps.

Jake

------------------
1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9



[This message has been edited by JakeJr (edited February 15, 2001).]

 

Thanks for all the replies. I already have been running the ZZ-9 camshaft in my car with the recommended valve springs from TPIS. It already has a mildly lopey idle as it is with the 1.5 rockers. So I will definitely have to have the slots elongated with 1.6 rocker arms? I have seen a tool that does this in the in either the Summit or Jeg's Catalog. Will this work while the heads are still on the block or will I have metal shavings fall into the motor? Would I be better off doing this when the heads are off. If this is the case, will the AFR 190 cc Aluminum Heads have to have the slots elongated as well? I plan to purchase these heads in the near future.

------------------
1988 GTA 5.7L Auto
355 ci. block, SLP Cold Air Intake w/ K&N, fully modified MAF Sensor, TPIS 52mm Throttle Body w/Air Foil, Throttle Body Bypass Hose, Fully Ported and Polished Plenum, Nikel-plated Ported SLP Siamesed Runners, Ported TPIS Big Mouth Intake Manifold, stock heads w/ 1.52 Comp Cams Self-aligning Roller Rockers, TPIS ZZ-9 Roller Camshaft, TPIS Valve Springs, Cloyes True Double Roller Timing Chain, TPIS Adjustable Fuel Pressure Regulator, Balanced Bosch 22 lb/hr Fuel Injectors, MSD 6AL, Taylor 10mm Wires, Bosch Platinum +4 Spark Plugs, MSD Blaster Coil, March Underdrive Pulleys, 6 3/4" Vibratech Streetdamper, TPIS Level 4 PROM, 160 T-stat, Low Temp. Fan Switch, Stock Distributor w/ Bronze Gear, SLP 1 3/4" Headers, Random Technologies High Flow Cat., Adjustable Borla Cat Back Exhaust, Level 10 PTS-3 700R4 Trans, B&M Holeshot 2400 Stall Converter, B&M Trans Cooler, TCI Aluminum Finned Trans Pan, Torque Converter Lock Up Switch, 3" Balanced Aluminum Driveshaft, 3.73 Richmond Gears, Auburn Pro-Series Differential, LPE Aluminum Differential Cover w/ Main Cap Preloads, BF Goodrich Drag Radials 255/50 R16, Hotchkis Lower Control Arms, Hotchkis Panhard Rod, Hotchkis Tie Rod Adjuster Sleeves, Bilstein Heavy Duty Shocks and Struts, 1LE Springs, Energy Suspension Polyeurethane Bushings, Global West Tubular Subframe Connectors, Global West Steering Box Brace, HP Motorsports 3 Point Strut Tower Brace

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

You'll need to pull the heads since there will be a log of cast iron shavings flying around. They'll need to be thoroughly cleaned afterwards too to make sure all the CI has been removed. This should include removing the springs and valves.

Aftermarket heads are set to go with the required mods already done.

Jake

------------------
1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9