Cams and drivablility
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by Kara
What do you guys prefer, the gm847 or 306?
Duration @.050 242/252 lift .56x/.56x w/1.6RR's on a 110CL
This is a hydrolic cam that has been tested at a GM tester that built my engine and said it has amazing results...we'll see in about two weeks!
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
For good idle for a mild 350cid keep overlap to around 35deg or less.
Add advertised durations (at .004") for int & exh, divide by 4 and subtract the LSA to get overlap.
Using the ZZ9 cam for example (I happen to have the numbers for it):
advertised durations are 282/287=int/exh; LSA is 112. So,
overlap == (282 + 287 ) / 4 - 112 = 569/4 - 112 = 142-112 = 35deg.
Add advertised durations (at .004") for int & exh, divide by 4 and subtract the LSA to get overlap.
Using the ZZ9 cam for example (I happen to have the numbers for it):
advertised durations are 282/287=int/exh; LSA is 112. So,
overlap == (282 + 287 ) / 4 - 112 = 569/4 - 112 = 142-112 = 35deg.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
For good idle for a mild 350cid keep overlap to around 35deg or less.
Add advertised durations (at .004") for int & exh, divide by 4 and subtract the LSA to get overlap.
Using the ZZ9 cam for example (I happen to have the numbers for it):
advertised durations are 282/287=int/exh; LSA is 112. So,
overlap == (282 + 287 ) / 4 - 112 = 569/4 - 112 = 142-112 = 35deg.
Add advertised durations (at .004") for int & exh, divide by 4 and subtract the LSA to get overlap.
Using the ZZ9 cam for example (I happen to have the numbers for it):
advertised durations are 282/287=int/exh; LSA is 112. So,
overlap == (282 + 287 ) / 4 - 112 = 569/4 - 112 = 142-112 = 35deg.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
For good idle for a mild 350cid keep overlap to around 35deg or less.
Add advertised durations (at .004") for int & exh, divide by 4 and subtract the LSA to get overlap.
Using the ZZ9 cam for example (I happen to have the numbers for it):
advertised durations are 282/287=int/exh; LSA is 112. So,
overlap == (282 + 287 ) / 4 - 112 = 569/4 - 112 = 142-112 = 35deg.
Add advertised durations (at .004") for int & exh, divide by 4 and subtract the LSA to get overlap.
Using the ZZ9 cam for example (I happen to have the numbers for it):
advertised durations are 282/287=int/exh; LSA is 112. So,
overlap == (282 + 287 ) / 4 - 112 = 569/4 - 112 = 142-112 = 35deg.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Originally Posted by Kara
What do you guys prefer, the gm847 or 306?
Stick with the GM 846 or CC 305. I was at 363rwhp with the LT4 HOTCam. I expect to be close to 375-380 with my 846 cam when I get some dyno time in a few weeks. 1/4 mile times? I don't care...I road race.
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
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Originally Posted by Kara
The Lt4 just wasnt enough. Alot of the camaro guys seem to love the gm847
If the car is 90% street driven and the engine is going to remain a 350, then you better be prepared for a rough idle and a loss in low end torque. If the car is a 6 speed be prepared for cam surge right at the typical cruising rpms. If you have an auto, you'll need a different torque converter (2800 or 3200 stall) for street manners.
In addition to the above, it'll need custom tuning just to get the power numbers the cams are capable of. If you're a perfectionist, be prepared for a lot of frustration if you have to have someone else tune it for you. Some of the above can be tuned out (to some extent). Unfortunately, it just means more time, more $$, and more frustration.
Of course all the above is pointless without a decent set of cylinder heads, the correct valvetrain, and a different exhaust since the cam will be inhaling and exhaling thru proverbial soda straws.
