ricoc

Ordered this for a 5.3 with stock intake and exhaust manifolds. I know it'll be lumpy if nothing else.


Camshaft Specification Table
Part Number 54-426-11
Engine 1997-Present General Motors
4.8ltr-6ltr
Gen III/LS1/LS2/LS6,
8cyl.
Grind Number XR275HR
Description

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Intake Exhaust
Valve Adjustment 1 1
Gross Valve Lift 0.566 0.568
Duration At 0.006 Tappet Lift 275 277

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Valve Timing At 0.006
Open Close
Intake 28 68
Exhaust 73 25

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These Specs Are For The Cam Installed At 110 Intake CL
Intake Exhaust
Duration At 0.05 222 224
Lobe Lift 0.333 0.334
Lobe Separation 112

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Recommended Valve Springs 26918-16

ricoc

I think I found my answer.

https://www.performancetrucks.net/fo...=392089&page=1

zapata41

so have you installed it, i went with a 259hr and wish i went bigger

ricoc

no, waiting for shipping

InchUp

iTrader: (2)

The 275 may not do so well in the 5.3L. Remember all it's specs are designed for the LS1. You're looking at a rev range of 1,800-6,800 in a 346 cube motor but 1935-7313 in the 5.3L. Ouch if this is your daily.

00Silv4.8

iTrader: (10)

with a lower power range I'd think it'd be better in a DD. I think it'll be fine in ur 5.3. With a **** *** tune my 4.8s doin fine with a 221/221 .558/.558 on a 114
--Gas mileage is definately an all time low, hopin my tune soon will belp

ricoc

I hadn't done the math like that. I am thinking that the intake and exhaust manifolds are relatively matched. For the expense and hassle of the cam, I'll take the go big or go home angle. As far as the displacement and compression ratio comparisons, I'm gambling that can be overcome with RPM. So, maybe it will still pull past 7000. Gas milage is an extension of my big toe.

JDC

iTrader: (3)

Thats the same cam comp recommended for my up grades. just havent got one yet.

InchUp

iTrader: (2)

There are others on this site who I've spoke to about this, and the general consensus amongst all of us is that you find yourself the cam you want, and drop down one "size". For example if you're set on the XR275, get the XR265 instead. Too many guys and gals on here look at the LS1 guys for answers but when it comes down to lugging around an extra ton of weight we're left with a dog for a truck following the cars. Trucks need low end power to get their weight moving and to keep some semblance of daily driver manners. Less is more in this case and the "Go big or go home" attitude that took years for me to get out of always has me picking the smaller cam.

I do not think the finest tuning skills would be able to tame that camshaft in a 325ci motor. It's just too big in my opinion. I'd get the XR265 if you want a fast truck or a XR259 if you want your truck to act like a truck.

ricoc

Hopefully, the smaller valve size will make the cam seem smaller.
I only had this truck on the road for 1 month last year. It was time for drastic change. Notice on the 5.7 graph that power was peaking in the 6500 range. I'm still waiting for the cam and looking for injectors. The local wrecker here wants $600 for 8.1's