Intake runners

[89ZZ4]

Bill C

You need to find out what type of roller rockers they are. (ie self aligning or not) If not then you will need guide plates and hardened push rods. The TPIS ZZ9 cams are all designed around the 1.5 ratio rockers (Per TPIS). This cam with your stock springs could get a little iffy on the exhaust side using 1.5 ratios. Using 1.6 ratios bumps the gross lift up way beyond the springs ability.
If the rockers you can score cheap are narrow body self aligned it might be a good deal. You can get either ratio - self aligning - GM Performance Parts for 3/8 stud through Scoggins Dickey for about $280. They are made by Crane.

89ZZ4

 

[Fastvette86]

Bill C,

I don't have any parts for sale other than my stock runners and manifold base. I was refering to the big mouth base and runners that you said you could get for $350 - that's a real deal. 89ZZ4 said that you need to check if you need self aligning rockers or not. TPIS says that 89 to 91 Vettes need them. I have stock alum heads and used regular rockers. It's hard to tell if your guide plates are hardened or just there to hold the push rods while the factory builds the engine. Then in doubt, buy new hardened guide plates. Talk to TPIS about their latest cams and spring recommendations. They were very helpful to me. The best roller rockers are Comp Cam's stainless steel rockers, much tougher than aluminum. You need to remove the oil drip fingers inside your valve covers for most roller rockers. Nate's engine had stamped steel center bolt covers and the GM Performance alum rockers fit fine. His iron Vortec heads required self aligning rockers - got them from Scoggen Dicky. Comp and Crane also have them. I put Comp cams 1.6 magnum roller tip rocker on my Vette that cost $120. They're not full rollers, but I didn't have to modify my valve covers. Buy TPIS's book "Insider Hints", it will really get you up to speed on L98 mods. As for breaking parts, I don't think you will unless you use slicks or run the 1/4 mile lots.

 

[Bill C]

I just agreeded to purchase a set of SLP runners. I am going to port the rest of the system by hand! Now the project begins!! Wish me luck. I will be taking LOTS of digital pictures and will pass the interesting ones along!!!

Too bad I cant dyno the car prior to the start of the rebuild. I have the G-tec results from about a year ago.

the following set up was established, street tires, open exhaust (sounded like a stock car ) , 92degree ambiant air temp, 175 deg engine temp; RUN 1 0-60 = 5.48, 1/4 mile =14.25

210 deg engine tem; RUN 2 1/4 mile14.39

the horsepower that the thing recorded was 240-260 "BUT" I didnt write down the weight that I programmed in for the car.

Bill C

 

[JavierN]

Bill C

Cool, are you getting the ZZ9 cam from TPIS? Let us know the changes on your 1/4 mile timing.

 

[Bill C]

Well,,,,,,the project begins. I purchased a set of SLP runners for $120 and I am going to port the stock base. I have two stock TPI units so if I goof it up I can recover:cool The stock plenum is already ported to death. I will try to take pictures and log all of the progress! The engine will be disassembled in April and the build up completed in May! Maybe if ALL goes well and the money holds out :eyerole

Bill C