Im gonna be building another 5.3l for my truck cuz it has 236,000 miles on it so its gettin pretty wore out, but in the new motor im building i want to put a XR265HR-15 cam in it, I was wondering with that cam should I get heavy duty pushrods, valve springs, and new lifters and rockers or would the stock ones be ok? Im still learning on building motors im only 17 but I no what im doing I just want to know if anybody put that same cam in and what else you did for the motor, I want a good reliable motor with decent mpg since its my daily driver

 

Get you some comp 918 springs and some 7.4 hardened pushrods from any of the site sponsers and you'll be good to go in the new motor. You'll of course need a tune afterwards. A looser converter would help get it moving as well.

Where are you located in OK?

 

At 236k miles I'd go for new rockers just for peace of mind. The factory ones are just one for that cam, it's the same one I have. I've got a circle d 2800 stall that works amazingly but if all you can afford at the time is the cam and supporting parts, the stock converter will be fine for the time being. I've got ls6 springs though you don't need to spend the coin on 918's. and go with ls7 lifters

 

And I get mid-high 16's, low 17's if I'm nice and in optimal conditions. That's with heavy *** centerlines and d range 285/75r16 falken wild peaks

 

Well i can get Ls6 springs for really cheap, so should I just get some of those? With new rockers and 7.4 pushrods? Yall think thatd be a pretty good setup with that cam? Well the thing about my mpg is after my motor is done im puting a 6" lift with 315's on it....but to help the mpg im gonna change the rear end ratio from 3.73 to 4.10, I heard that helps mpg running 315's

 

That's a great cam for a 5.3 , I had the same one in my old 04 turbo Z71. Loved it , sounded great and performed excellent at all ranges , I also had a 2800 PI converter.

Anyway I wouldn't touch comp springs , too many probs . For you Z06 springs are perfect like said above . Also if your freshening up your current engine get a set of LS7 lifters ,don't run high mileage lifters with a new cam, maybe try to find some lower mileage rockers but I don't think it's that big a deal , these engines last along time , I wouldn't be too worried with the mileage . But also def do a new LS6 oil pump/ LS2 timing chain , and a new water pump while your at it .

 

Most of the people on here say to go 2 ratios up over stock so 4.56's for 315's...
Get your cam, hardened 7.4" pushrods, got mine from eBay for like 89 bucks, new rockers if you want, but stockers will be fine, no need to go fancy as they're not really cost effective. Ls7 lifters, ls2 timing chain (make sure it's a 3 bolt) and an ls6 oil pump

 

I'd stay with stock rockers and do the tunnion upgrade on them. Hardened pushrods, LS6 springs. Should be good.

 

If you're getting a different engine why not step up to a 6.0 and toss a baby cam in that? You'll have much more power right off idle and the cam will make the top end feel like a rocket compared to your tired 5.3

 

^what he said you would probably be a lot cheaper with a low mile motor because gaskets and rings and machine shop fees add up fast