Courtntan

First post, go easy. Last summer I swapped a LM7 from an 03 Silverado into my 96 rcsb. Couldn't be happier, runs great, lots of power and super fun to drive, but..... I want more. I work at a garage and I've got a 5.3l gen IV out of an 07 sitting on a stand. It has some dod lifter problems, but it also has 243 heads and the nnbs intake and tb.

So the swap is kind of a no brainer, right? Now the questions.

Best to have the heads milled 0.03?

What Comp Cam would you guys recommend for a weekend driven, small truck with a 2600 stall, no cats, cai, shorty headers (ya, I know, they were almost free), 3.42 with a very short 295/50/15 tire. Also will be tuned with HP Tuners.
The local parts guy owes me some cash, so I'm trying to stick with comp because he can get that.

Are new valve springs needed? Trying to build on a budget.

Looking to try to hit low 13's N/A, is it possible? All help and suggestions are appreciated, tried searching, but everyone else's set up is just a bit different than mine.

Courtntan

Sure is lonely in here.

Beatdown Z

iTrader: (18)

Something like the 212/218 "low lift", 212/216, or 216/220 would work great. Throw in some $50 LS6 springs and call it good.

Courtntan

Thanks for the reply, I was thinking the XR275HR might be a good cam, you think that's too big? It's a 222/224 on 112 lsa. I don't might giving up some drivability for a few extra et. Would the ls6 springs work with this cam?

zero2sixT

iTrader: (4)

^That cam will work pretty good in the gen IV.

Id also run pac springs instead of the ls6s.

dmelvin

iTrader: (8)

The LS6 springs work well for the cams that he suggested, the 222/224 however also has a bit more lift. The LS6 springs would probably still work alright, but you'd be stressing their ability with the ramp rate on that cam and may end up running into some valve float in the upper RPM's.

Since you're in a standard cab, that cam with the 2600 torque converter will probably be alright since it's on a 112 LSA. Anything bigger and you're not going to have enough converter.

You don't have great gears, but you're making up with it somewhat with your tire size. If you went to bigger tires, I think your low end will be abysmal. Since you're 2x4, I'd be looking into a gear change before too long.

Courtntan

Ya, I figured the gears would be an issue. I have a set of used 3.73's at the shop, but I wasn't sure that I wanted to go through the trouble of setting the rear end all up. I was hoping that the 3.42's with low tires would make up the difference. I'm going to order the cam tomorrow, get my heads milled, but it will probably be a few months before I can get it all together. I'll run it before and after and post up the results. Thanks for the help guys.

zero2sixT

iTrader: (4)

Id get it running with the gen IV 5.3 before I swapped gear ratios. You may like the 3.42s. Especially with a 28" or 29" tall tire. There was a GMT-900 reg cab on here with a 5.3 running a larger cam and 3.42s. It ran high 12s.

Id also save my money on milling the heads.

Courtntan

The motor is actually a gen 3 that I'm planning on dropping the gen IV heads and intake/TB on to, with the cam. I'll have to mill them to keep the compression ratio up. The tires I'm running are around 26", so my final gearing will be really close to a 29" tire and 3.73's. At 50mph the 26" tall tire with 3.42's will turn approximately 2658rpm, a 29" with 3.73's will turn 2656rpm. Hi 12's is a goal I'd like to hit eventually, but mid to low 13's is my short term goal.

zero2sixT

iTrader: (4)

Ah, its clear to me now. From your first post, I thought you were going to run the gen IV.

Sorry, yes you are right. You should mill the 243s.

And yeah that is how I would do it. Manipulate the rear end gear ratio with tire height. Good luck man