superls1

Looking for some advice on a H&C setup for a 2005 Avalanche. I already have some Dynatech headers. A cam being promoted on the truck site and in the magazines is from Crane: 210/218 .551/.551 116. However, they recommend using 1.8 rockers to get the lift to .583.

I was wanting to run some AFR 205's. I would need to have them milled .030-.035 to keep the compression ratio the same (.035 would slightly increace it ).

This isn't a problem, but will I have any P-V issues with 2.02/1.6 valves, heads milled .035, and .583 lift? Also, the AFR stock springs are good to .600. Do I need a better spring? If it does all work, what length pushrod would I need?

I did talk to AFR. AFR says milling them .030-.035 is not a problem, and that they routinely take the heads down to approximately 62cc's. However, the guy at AFR was not familiar with the 5.3 motor at all, and he had no idea whether the cam would have P-V issues or pushrod length. He also indicated that a 210/218 is too big of a split for their heads and that it would not 'maximize' low end torqure or top end power. He recommended something more like 214/218. He said this was due to their I/E airflow ratio being so much better than stock style heads. He also indicated that the .580 lift area is a 'sweet spot' for their heads.

Bo White

iTrader: (59)

I would run the later LS6 cam if you wanted to save a few bucks but since you are considering AFRs I assume thats not a problem. The split is a little big for a N/A engine with a great set of heads and exhaust and would probably run a single pattern if it was me. I also would mill a little more for more compression, but not too much since it is a truck so it wont want to ping on ya if you tow. The pushrod length is the same as the LS1 so just get rods that are shortened the same amount as the amount milled, most rods are available in .025" increments. Call Comp Cams and see what they say on cam recommendation

superls1

I have been looking into some single pattern profiles as well. I want to keep the compression between 9.5:1 to 10:1. I was just worried about P-V issues after milling that much. I didn't know if the 5.3 was any different than an LS1/6 in regard to P-V (how much the piston was out the hole or any other difference). I want more power, but I particularly want more 'grunt' down low. I will probably just need to get some gears to satisfy me there. Although gas prices don't make gears look very enticing.

Would still recommend a single pattern if I plan to go with a Whipple, Magna, etc in the near future?

Bo White

iTrader: (59)

I would look into a 4 degree split if that is the case down the road. I do not think PtoV is a problem with the size cams you are lookin at.