L98 cam swap?
Thread Starter
Junior Member
Joined: Jul 2002
Posts: 3
Likes: 0
From: Sacramento Ca.
L98 cam swap?
Does anyone have opinions on a good cam and head combination
for CA emission? The car is a stock 91 GTA, L98 TPI.
I got about $2,000 to work with.
for CA emission? The car is a stock 91 GTA, L98 TPI.
I got about $2,000 to work with.
Last edited by Mrmenu1; Sep 21, 2002 at 02:57 AM.
Joined: Mar 2000
Posts: 43,187
Likes: 46
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
This is more of a tech question than motor swap, but...
The key to emissions is to keep the cam duration and overlap down so the amount of unburnt fuel going out the exhaust valve is kept to a minimum; and keeping the computer happy. There are a couple of ways to go about that: GM cams, such as ZZ4 or LT4 Hot Cam (you'll need TPI changes such as shorter runners to be able to take advantage of them); or aftermarket computer-compatible cams such as those from Crane or Comp. Personally, I'm impressed with my Crane.
For heads, there are a lot of choices. The most obvious is to port the heads you have now, upgrade the rocker studs to screw-in type, upgrade the springs to match the cam, upgrade the rockers to at least roller tip. The World S/R Torquers are good, but the '87-up versions only come in the larger chamber (you can use the '86-older version with the smaller chambers with minor modifications to the intake base mount bolt holes). World heads typically benefit greatly from some bowl and porting work, but they already have the screw-in studs and upgrading the springs when you order them is cheap. AFR makes great stuff, 195's would probably be all the bigger you'd want to go. GM Vette L98 heads are decent, porting work helps them. I haven't heard of many people that are impressed with the Holley or Edelbrock heads, but they're out there as well.
The key to emissions is to keep the cam duration and overlap down so the amount of unburnt fuel going out the exhaust valve is kept to a minimum; and keeping the computer happy. There are a couple of ways to go about that: GM cams, such as ZZ4 or LT4 Hot Cam (you'll need TPI changes such as shorter runners to be able to take advantage of them); or aftermarket computer-compatible cams such as those from Crane or Comp. Personally, I'm impressed with my Crane.
For heads, there are a lot of choices. The most obvious is to port the heads you have now, upgrade the rocker studs to screw-in type, upgrade the springs to match the cam, upgrade the rockers to at least roller tip. The World S/R Torquers are good, but the '87-up versions only come in the larger chamber (you can use the '86-older version with the smaller chambers with minor modifications to the intake base mount bolt holes). World heads typically benefit greatly from some bowl and porting work, but they already have the screw-in studs and upgrading the springs when you order them is cheap. AFR makes great stuff, 195's would probably be all the bigger you'd want to go. GM Vette L98 heads are decent, porting work helps them. I haven't heard of many people that are impressed with the Holley or Edelbrock heads, but they're out there as well.
Thread
Thread Starter
Forum
Replies
Last Post
Hello, Michael
Engine Swap
8
Aug 20, 2015 03:19 PM
