# 2005 GTO Camshaft Installation



## gtodad (Oct 14, 2008)

We are thinking about changing the cam in my son's 05 GTO. Can this be done without removing the engine? Is there enough room to pull it out by just removing the radiator assembly?


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## GM4life (Mar 18, 2007)

Yes you can remove the cam without pulling the engine. All you need to do is pull the radiator and AC condensor. Let me know if you need help I changed mine.

This is an LS1 but the LS2 is very simular.


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## taz4141 (Nov 6, 2006)

boy . do i remember being here. be careful not to brake any of the clips that hold the front assembly. take your time.. oh and FYI scene your there ?... PIN THE CRANK PULLEY. you'll thank us later. are you going to do the heads? 


GM4LIFE nice pic bud. brings back memories. love this sh!t


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## Sticks_n_Stones (Mar 10, 2009)

What does "Pin the crank pulley" mean? Pop up lifters I've heard, but what about the valve springs - do the aftermarket ones fit the stock spring pocket so its just a quick swap?

I keep reading where you guys are changing out your lifters and pushrods along with the cam change. Is it really required? Not like the spring pressure is gonna be that much more than stock I would think.


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## taz4141 (Nov 6, 2006)

Sticks_n_Stones said:


> What does "Pin the crank pulley" mean? Pop up lifters I've heard, but what about the valve springs - do the aftermarket ones fit the stock spring pocket so its just a quick swap?
> 
> I keep reading where you guys are changing out your lifters and pushrods along with the cam change. Is it really required? Not like the spring pressure is gonna be that much more than stock I would think.



the meaning of duration on a cam, mild or radical. means that the valve is opening a little longer. the lob of the cam becomes sharper and taller to open and close the valve. when this occurs, the valves close harder and opens faster, in turn give you more duration. there for stock springs can't keep up.

(in short, heaver springs means faster reaction time for the valve's)

if the valve don't close as fast as the cam is moving per lift and duration. we call this floating the valve. in the same tolken the piston is on it's way up if valve is not closed per the cam. piston hits valve and you walk. or 
the keepers fall out and BANG goes the valve, it's now in the cylinder and by by piston. this is the short story other can explain this better i'm sure.

as far as keepers and guides stock GM parts are for lack of better words (soft) titanium is the ticket. same for push rods except the new ones are hardened chrome alloy. the lifters, creates a pattern called a scar in to the factory cam, so when we put a new cam in we start with a fresh surface's both cam and lifter's and push rods, so that the two new surfaces can create there own scars other wise.... the old scars from the old lifters will create gully and gouges on the new cam and will shorten the life of the cam and lifter's dramatically. 

pin the crank pulley AKA the harmonic balancer. this is a horse power issue. the more hp you crate the more it take to turn internal parts as well as external parts. putting a lot of strain on the surp belt. the crank is where it all happens all the energy that come from the combustion is all now being diverted in to a circular motion at the crank. well... the crank pulley that is installed by press fit or (static fit) and a large bolt,can technically move and will, when greater hp is being crated. the serp belt is attached to a series of pulley's and drives the other components, power steering, alt, water pump ect... now dump 450 plus horse power to the crank what happens. the crank pully has all the load of driving the components that are in essence standing still. that poor little surface where the crank and pulley are connected, slips and fail. there for. if you pin the crank to the pulley(key way)(hardened dowel pins) this surface is now stationary or blocked from the possibility of spinning. personal i think these should be spline fitted from the factory


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## Sticks_n_Stones (Mar 10, 2009)

Wasn't aware the drive pulley was a press fit, why would GM do that on a quick revving engine? Pin the pulley simply means grind in a key way on the crank to be used by the balancer. How do you manage to do that with it still in the engine? There aint much room to operate a lathe there! BTW: the HP a car makes has no relation to the strain put on the drive pulley, other than if all other things remain the same it will accellerate faster up the rpm band in gear. Or more accurately, the faster it will spin up when you rev it in neutral.

I'm very very familiar with valve float etc.., I've installed at least 20 cams in small block chevy's and a few in Mopars. I was simply referring to GM's habit of using small diameter valve springs which normally require machining of the valve spring pocket on the heads to fit larger springs. Also, normally you can reuse GM roller lifters if they are under ?40-50k miles of use? - at least according to GM Performance Parts. Roller lifters do not seat to the cam like regular flat tappet lifters do, there paths of travel vary enough that they do not 'seat' like you are referring to. 

I've been out of the tuning/racing scene since 2002 when I moved into motorcycle racing, so what I used to know could easily have changed - like GM using a press fit on there balancer. That sh*t used to only be done on slow n cheap little 4 cylinder junk...


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## taz4141 (Nov 6, 2006)

well that's what they did. me and gm4life can testify to this. so I really didn't need to explain all this to you. but thats ok . some one else may find this useful. i wouldn't say that gm uses crap in there builds. but it's good enough for what it does and no more. if you see my meaning. they build to make the car run for 100k or more with out major brake down but they seem to build this stuff to go out right after the warranty is out.


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## GM4life (Mar 18, 2007)

Taz4141 is correct. Being not much space to pin the crank you'll want to do it while your changing the cam as he was saying earlier. GM has you torque the crank bolt to 240 ft lbs. But many have found out that it will back out on you as the crank pulley spins expecially folks with superchargers. Thats why GM keyed the crank just like on SB and BB chevys on the supercharged LS9 and LSA engines. Crank pinning is easy to do if you have good drill bits. You can order the kit from places like Speed Inc. Now if you been in the car world long enough you must have seen the damage a harmonic damper could do when it flys apart or comes off the crank pulley, is not a pretty sight.


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