Im about to tear into my topend and i need opinions on parts. What roller rockers, pushrods, lifters, and cam should i get. I was thinking along the lines of a cc306, the gm847 sounds wicked but i know thats over kill on stock heads and the 306 has plenty of lope. This isnt my daily drive so im not too concerned about noise and drivability. I was just wondering what other things i may need.
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Not going to tell you what to get, but go mild on duration since you have an A4 & stock converter. And IF you go with a mild cam, you can keep the stock lifters if they aren't worn out or damaged. You UG the cam, etc, don't leave out valve springs - very important. -
Are you getting the heads ported? If not, anything bigger than the LT4 Hotcam/ springs would be a waste of time and money. The reason is because stock LT1 castings hit the wall at about .400" of lift.
The CC306 isn't even a good choice for fully ported heads, much less stock heads.
The CC306 cam is ground on technology that is over 20 years old. The CC306 is effectively all bark and no bite. There are much, much better cams available for LT1's that will provide much more power, much better idle characteristics, and better overall driveability.
The CC306 is listed as 230/244 @ .050", .510"/.540", 112 LSA. With that much split in the duration and in comparison to the relatively small amount of the lift, the CC306 is a very choppy cam that will be very soft down low. It would be horrible with a stock converter. With a 244 exhaust valve duration and .540" of exhaust valve lift on a 112 LSA, you are going to have a significant overlap without the effective intake or exhaust lift to support it or the intake duration to support it. You would need at minimum a 3000 stall to make this cam worth driving on the street.
There are a few ways to calculate degrees of overlap. I'll use the advertised duration and lobe separation angle method since I do not know offhand the specific IVO or the EVC timing of the CC306 camshaft.
First you add the advertised intake and exhaust duration together. Then you divide that sum by 4. Then subtract the LSA. Then multiply that by 2.
290+307 = 597
597/4 = 149.25
149.25-112 = 37.25
37.25 * 2 = 74.5
So the total valve overlap is approximately 74.5°. That is a bunch of overlap for such a large split in duration and relatively small lift. Like mentioned above, the profile of this cam cannot effectively support the overlap. Thus you end up with a rough cam that doesn't make really good power for what it is.
Call up someone like Advanced Induction, Combination Motorsports, or Thuner Racing and tell them what you are doing and get them to reccommend a cam.Comment
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i went with advanced induction in NC..good company to work with and they will work with you to find out what youre expecting out of your car. call Ron up and tell him youre interested in a quote..and he will take care of the rest.
Originally posted by fastTA-JeffComment
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