L98 performance suggestions
Thread Starter
Heel & Toe
Joined: Sep 2007
Posts: 15
Likes: 0
L98 performance suggestions
I am working on a project 1985 Corvette. It started bucking and popping so I think the timing chain is shot. I plan to tear it down the top of the engine over the winter and do some replacement. It uses no oil and carries 150 lbs compression per cylinder. It is a low value driver Vette with 172k miles 
so I am unconcerned about maintaining originality.
I want to keep the TPI stock so as not to mess up my electronics or computer. I will replace the timing chain of course with a double roller. While it is torn down, are there any suggestions out there for the following:
- Cam (roller, non roller, specs?)
- Rockers (1.5, 1.6, roller?)
- Heads (valve size, CCs, compression?)
My goals is 50 to 75 horsepower over stock with good drivability. Is this within reason and how should I go about it. I am open to all suggestions.
so I am unconcerned about maintaining originality.I want to keep the TPI stock so as not to mess up my electronics or computer. I will replace the timing chain of course with a double roller. While it is torn down, are there any suggestions out there for the following:
- Cam (roller, non roller, specs?)
- Rockers (1.5, 1.6, roller?)
- Heads (valve size, CCs, compression?)
My goals is 50 to 75 horsepower over stock with good drivability. Is this within reason and how should I go about it. I am open to all suggestions.
Pro
Joined: Sep 2005
Posts: 747
Likes: 0
From: Calgary '85 Z51 coupe
Heads and camshaft are always key to making power but if you don't touch the intake/exhaust you will be limiting yourself.
You should think about porting the plenum, intake, get some larger runners and put some alum heads on there--the computer should handle that.
Roller cams are nice but not cheap.
If you search you will find lots of threads with suggestions on heads and cams.
You should think about porting the plenum, intake, get some larger runners and put some alum heads on there--the computer should handle that.
Roller cams are nice but not cheap.
If you search you will find lots of threads with suggestions on heads and cams.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Team Owner
Joined: Oct 2004
Posts: 35,065
Likes: 0
From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
I"m getting there. I picked up the parts (oil pan, intake, valve covers, water pump, and brackets) from the powder coaters, and I just wasn't happy. I had to have them done over.
I had a problem getting the right timing chain, which set me back a week.
I had to travel for work, last week, and this week.
When I get back next monday, I will pick up the parts from the powder coater, and assembly will begin.
I'd start the assembly now, but I want to check the intake base to the 1204 gaskets before I mount the heads, in case I have to take a little off the heads. I read that the Super Ram is 1205 gaskets, but I don't konw if that's standard or worked.
Guess I can just ask the question....
I had a problem getting the right timing chain, which set me back a week.
I had to travel for work, last week, and this week.
When I get back next monday, I will pick up the parts from the powder coater, and assembly will begin.
I'd start the assembly now, but I want to check the intake base to the 1204 gaskets before I mount the heads, in case I have to take a little off the heads. I read that the Super Ram is 1205 gaskets, but I don't konw if that's standard or worked.
Guess I can just ask the question....
Instructor
Joined: Jul 2006
Posts: 150
Likes: 2
Baseplate and runners. Port that plenum! I do that buy the way-Corvetteplenum.com
Exhaust is pretty good on the Vettes, heads are so-so. If your an '85 then you have the iron heads I think? Correct me if I'm wrong guys.
Vortec heads with the baseplate is a good deal and a definate step in the right direction.
Camshaft is key. I like the Lingenfelter 219. You can buy it new on ebay for about $250 and It's a very streetable cam that makes great power in the long tube TPI.
then there's tuning and of course I would expect your already performing the "free mods"
My advice, Do a little at a time. Drive it until you get bored and think about what you want to do next.....
Exhaust is pretty good on the Vettes, heads are so-so. If your an '85 then you have the iron heads I think? Correct me if I'm wrong guys.
Vortec heads with the baseplate is a good deal and a definate step in the right direction.
Camshaft is key. I like the Lingenfelter 219. You can buy it new on ebay for about $250 and It's a very streetable cam that makes great power in the long tube TPI.
then there's tuning and of course I would expect your already performing the "free mods"
My advice, Do a little at a time. Drive it until you get bored and think about what you want to do next.....
Thread Starter
Heel & Toe
Joined: Sep 2007
Posts: 15
Likes: 0
Right now I am pretty scared to tackle the complexity and tightness of all that stuff under the clamshell. I am afraid I will never get it back together. I have moments when I think I need to sell it for parts and buy a finished one. But all of you, please be more specific. What heads? What cam? What exhaust?
Team Owner
Joined: Sep 2001
Posts: 62,153
Likes: 1,731
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
What heads and what cam depend on the total plan and goals. Since you do not have a roller, you at least need to look at cams with similar specs to the TPIS ZZ9, or Accel 211. Heads need to be no bigger than 180cc since this is staying TPI. Edelbrock 170cc would be a good set.
Exhaust choices are all based on sound preference, you have to hear them to decide. Headers are on fit & quality, like TPiS or Hooker.
Exhaust choices are all based on sound preference, you have to hear them to decide. Headers are on fit & quality, like TPiS or Hooker.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
What heads and what cam depend on the total plan and goals. Since you do not have a roller, you at least need to look at cams with similar specs to the TPIS ZZ9, or Accel 211. Heads need to be no bigger than 180cc since this is staying TPI. Edelbrock 170cc would be a good set.
Exhaust choices are all based on sound preference, you have to hear them to decide. Headers are on fit & quality, like TPiS or Hooker.
Exhaust choices are all based on sound preference, you have to hear them to decide. Headers are on fit & quality, like TPiS or Hooker.
Next step, start shopping these parts and see if you have the budget. This is not really a first timer home project. Do it all at once get a pro to install it if you have the money.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Exhaust work will not require changes to your stock computer chip. You can do almost anything to that engine, heads, intake, runners and plenum with chip changes. CHANGE THE CAM and you WILL have to change the chip.
You can do and achieve your 50-75 gain without touching the cam if you want. I am running the stock cam and pistons currently.
You can do and achieve your 50-75 gain without touching the cam if you want. I am running the stock cam and pistons currently.
Pro
Joined: Aug 2006
Posts: 682
Likes: 1
From: SpringHill florida
i dont know where ur from but i just put mufflr delete pipes and gutted the main cat,also ported the heads and intake, higher compression pistons, cam with like 490 lift,i still have stock headers and the car is still fast and looks completely stock when you pop the hood which is what i was looking for, also some 1.6RR an underdrive pullies would help!
Team Owner
Joined: Sep 2002
Posts: 22,209
Likes: 12
From: OBAMA IS HITLER
L98? the entire system needs beefed up.
heads + cam + intake + LT headers/exhaust......minimum.
the above + added cubes, preferably.
add a supercharger, if desired.
if i had it to do over again, i'd do ALL of the above. and i've got no goals, i don't go to the strip.
heads + cam + intake + LT headers/exhaust......minimum.
the above + added cubes, preferably.
add a supercharger, if desired.
if i had it to do over again, i'd do ALL of the above. and i've got no goals, i don't go to the strip.
Team Owner
Joined: Oct 2004
Posts: 35,065
Likes: 0
From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
