LM7 cam swap parts?

[Swoll__]

So, I was thinking about swapping my cam out of my lm7 5.3 in my 2004 Yukon with the Chopcabra kit from Michigan motorsports (25-TSPCHOPacabra-Kit1). it comes with new springs and hat seals, so I was thinking I might as well replace my rockers with the ls1 rockers with the upgraded trunnions (25100) and ls7 lifters (AJ261+97500-04) while I'm at it. Now, I am pretty sure with replacing these I will have to get a new length of pushrods. what do you guys recommend? Will I have to get a measuring tool, assemble everything, then get the right pushrods? also, is there any full gasket kits I should get? should I get the ARP bolts that most people get? and are there any other things I should replace while I am in there. I will be taking off the heads and everything internal is stock, I currently have about 280k miles on it. Thanks guys any input would be nice.

 

[Mudsport96]

RHP kit

You can leave out the manifold if you want. But, you can order everything you need form one page.... and it comes with personal tuning for your truck.

 

[Marky Dissod]

What axle gear(s) do you have? 'cause even if you have 4.10(s) - but ESPECIALLY if you've 3.73 or 3.42 (3.23, please, not 3.23)
you WILL lose some throttle response under 2500RpM. If you replace your torque converter with one that has a higher stall RpM, you WILL lose MpGs.

...
pretty sure with replacing these I will have to get a new length of pushrods. what do you guys recommend?
Will I have to get a measuring tool, assemble everything, then get the right pushrods?

You won't know for sure til you measure, right?

Since you're taking the heads off, replace the head gaskets. Since you're replacing the lifters, also replace the lifter bucket guide thingies.

It'd likely be more expensive, but you'd be happier with 4.10s in the long run.

 

[strutaeng]

What are trying to gain by swapping the cam? Just chop? You are okay giving up lower speed torque? IIRC that cam will make the truck less responsive at the lower end of the RPM range, leaving everything else stock. What tire size do you have? Axle gear ratio?

Stock hardware is just fine for a lightly modified engine. Some will upgrade to ARP, mainly to get a simpler torque spec on the head bolt, instead of the torque-to-yield (TTY) factory head bolts.

Pushrod length: there's a way to check by simply using the number of tuns of the bolt after you tighten the bolt by hand until all slop is taken out. I believe it's 1-2 turns; the nice thing is no special tools are required here. If you are not milling your heads, most aftermarket cams are still fine with the factory 7.4" pushrod length, but you should still very this. If you want to buy the pushrod checker, you'll also need a 8" or 12" dial caliper to measure the pushrod.

At 280k on the original motor, I would strongly recommend you remove the engine for a basic overhaul. Unless there are no leaks (RMS likes to leak at some point) and your oil pressure is still good.

 

[Mudsport96]

How many miles are on this rig? The 4l60e may be very unhappy with you if you do this

 

[swathdiver]

The TSP Chopacabra trades low end torque for more horsepower up higher where you spend the least amount of time with the engine.

Consider the Truck Torque or Truck Norris at the most. If I ever get around to putting a cam in my 5.3, it's going to be the Truck Torque. NO loss of power from idle to 6,500 rpms compared with the stock camshaft. It's the only one. Truck Norris minimizes this with a tight LSA but still loses torque below 2700 rpms compared to stock.

 

[strutaeng]

How many miles are on this rig? The 4l60e may be very unhappy with you if you do this

He said 280k miles..."I currently have about 280k miles on it."

So, almost (0.59) a round-trip to the Moon!

 

[Marky Dissod]

The TSP Chopacabra trades low end torque for more horsepower up higher, where you spend the least amount of time with the engine ...
Truck Norris minimizes this with a tight LSA but still loses torque below 2700RpM compared to stock.

Another way to better get this point across:
Once you install either of these cams, your transmission (4L60E here) will (need to) downshift MORE often than it used to,
on top of the MpG loss mentioned earlier.

Consider the Truck Torque ... if I ever get around to putting a cam in my 5.3L, it's going to be the Truck Torque.
NO loss of power from idle to 6,500 RpM compared with the stock camshaft.

Somehow I think finding a pair of considerately used 4.10 axles would be a better investment, even if more expensive.

 

[Joseph Garcia]

IMO, it is not a good investment to open up a 280k motor, unless you are going to overhaul it fully, while it is opened up. If you proceed, I predict that the motor won't make it to 300k miles.

If you are looking for some more sound, get an aftermarket exhaust system, or a (fake) CAI.

If you are looking for a bit more giddy up and go, do what @Marky Dissod implied. Convert your truck to 4.10 gears. IMO, this is the single best performance change that you can make, short of forced induction.

To convert to 4.10 gears, it will cost you in the neighborhood of $4k-$5k, which would include a replacement and full rebuild of both the rear and front differentials. At 280k miles, you can't simple change out the gears, and expect it to last.

If you want to proceed, purchase a used rear and front differential from LKQ, and have them shipped to your house, or directly to a local shop that performs this type of work (Do your search for this shop first, before you start ordering the differentials). If you do the conversion this way, you won't lose the use of your truck, until both rebuilt differentials are ready for installation, and you won't have to be purchasing all of the individual parts.

You WON'T be sorry.

 

[Swoll__]

IMO, it is not a good investment to open up a 280k motor, unless you are going to overhaul it fully, while it is opened up. If you proceed, I predict that the motor won't make it to 300k miles.

If you are looking for some more sound, get an aftermarket exhaust system, or a (fake) CAI.

If you are looking for a bit more giddy up and go, do what @Marky Dissod implied. Convert your truck to 4.10 gears. IMO, this is the single best performance change that you can make, short of forced induction.

To convert to 4.10 gears, it will cost you in the neighborhood of $4k-$5k, which would include a replacement and full rebuild of both the rear and front differentials. At 280k miles, you can't simple change out the gears, and expect it to last.

If you want to proceed, purchase a used rear and front differential from LKQ, and have them shipped to your house, or directly to a local shop that performs this type of work (Do your search for this shop first, before you start ordering the differentials). If you do the conversion this way, you won't lose the use of your truck, until both rebuilt differentials are ready for installation, and you won't have to be purchasing all of the individual parts.

You WON'T be sorry.

So, it sounds like it isnt worth it to cam it, since i dont really care for the performance, i really just want a chop. ive never looked into swapping the gears, and i dont see myself spending about 4k on a rebuild. you say it isnt worth it to open up the engine, so should i just not replace anything? if the cam will only give me negative results then yea, it wouldnt be worth it, but are there any things i should change out or upgrade for more longevity? the truck does not leak at all and runs immaculately.
as i said i dont really care for performance, im not gonna be racing my baby, since its been by daily driver since i was 16 (now 22), and i would hate to hurt her.
I will be putting on some arh longtube headers with a whole new setup though.

Another way to better get this point across:
Once you install either of these cams, your transmission (4L60E here) will (need to) downshift MORE often than it used to,
on top of the MpG loss mentioned earlier.
Somehow I think finding a pair of considerately used 4.10 axles would be a better investment, even if more expensive.

thats another big no no for me, i do not want to put more wear and tear on my trans or decrease the mpgs, theyre already bad enough with these crazy gas prices.
thanks for the input guys i really appreciate your time and expertise. i just really like making new projects for myself since it keeps me busy and learning.

 

[Mudsport96]

He said 280k miles..."I currently have about 280k miles on it."

So, almost (0.59) a round-trip to the Moon!

I must need glasses. It was right there in front of me.

 

[Marky Dissod]

that's
another big no no for me, i do not want to put more wear and tear on my trans or decrease the MpGs ...

I get the appeal of aftermarket cams, but everyone forgets:
*only mod that makes the vehicle itself stronger, increases the tow rating, and protects the transmission instead of stressing it, is better axles

 

[Joseph Garcia]

So, it sounds like it isnt worth it to cam it, since i dont really care for the performance, i really just want a chop. ive never looked into swapping the gears, and i dont see myself spending about 4k on a rebuild. you say it isnt worth it to open up the engine, so should i just not replace anything? if the cam will only give me negative results then yea, it wouldnt be worth it, but are there any things i should change out or upgrade for more longevity? the truck does not leak at all and runs immaculately.
as i said i dont really care for performance, im not gonna be racing my baby, since its been by daily driver since i was 16 (now 22), and i would hate to hurt her.
I will be putting on some arh longtube headers with a whole new setup though.

thats another big no no for me, i do not want to put more wear and tear on my trans or decrease the mpgs, theyre already bad enough with these crazy gas prices.
thanks for the input guys i really appreciate your time and expertise. i just really like making new projects for myself since it keeps me busy and learning.

I understand all of your points, and you are certainly free to do whatever you want to do, and I support your desire to have some project work on your truck.

If all you want is the chop sound, I don't know of any other way to achieve it, other than a cam swap. Other folks on this Forum who are much more knowledgeable than me in this area will chime in. @Doubeleive @randeez @swathdiver @wjburken

I do want to correct you on your assumptions regarding the gear ratio change. In reality, the 4.10 gears will actually reduce the wear and tear on your motor and transmission, as the motor will spend less time in the low rpm's, where it is less efficient in load/rpms, and wasteful on gasoline. If you baby the truck, as you say, then the 4.10 gears will actually increase the longevity of the truck, AND improve gas mileage.

Regarding long tube headers, installed by themselves, they will do nothing, other than change the sound of the exhaust. An aftermarket muffler would be a better, cheaper, and easier installation alternative option, IMO.

If you want truck projects, then do maintenance projects on the truck to increase its longevity. At 280k miles, I would anticipate that there are several suspension related parts that could enjoy a refresh/replacement. Shocks/struts, control arms, ball joints, and all suspension bushings are all wear items that eventually need to be replaced.

In the engine bay, all heating and cooling hoses are likely on their last legs and should be replaced. Battery cables and ground straps may need replacement. All exposed electrical grounds could be inspected, cleaned and tightened.

Regarding motor longevity items, I don't know what your current oil pressure is, but if it is on the low side, you could replace the oil pump as a major project, and/or you could simply drop the oil pan and replace the O-ring on the oil pickup tube. If your oil pressure is good, then I would not recommend dropping the oil pan.

Hopefully, this gives you some things to think about, project-wise.

 

[Doubeleive]

at 280k I would probably just go here and save my self a whole lot of headaches

GM 8 Cylinder engines

Specializing in GM LS series engines, GM 5.3 engines and GM 6.0 engines. OEM remanufactured GM 8 cylinder engines featuring a 3 year/100,000 mile parts and labor warranty.

www.bestrebuiltengines.com

 

[swathdiver]

So, it sounds like it isnt worth it to cam it, since i dont really care for the performance, i really just want a chop. ive never looked into swapping the gears, and i dont see myself spending about 4k on a rebuild. you say it isnt worth it to open up the engine, so should i just not replace anything? if the cam will only give me negative results then yea, it wouldnt be worth it, but are there any things i should change out or upgrade for more longevity? the truck does not leak at all and runs immaculately.
as i said i dont really care for performance, im not gonna be racing my baby, since its been by daily driver since i was 16 (now 22), and i would hate to hurt her.
I will be putting on some arh longtube headers with a whole new setup though.

thats another big no no for me, i do not want to put more wear and tear on my trans or decrease the mpgs, theyre already bad enough with these crazy gas prices.
thanks for the input guys i really appreciate your time and expertise. i just really like making new projects for myself since it keeps me busy and learning.

You can get that choppy sound, or some version of it, through tuning and exhaust selection. Choppy camshafts are not daily drive friendly.

 

[strutaeng]

There should be some gizmo with some sort of speaker that gets mounted underneath the vehicle in the rear...

Said gizmo would play some super duper LOUD "chop, chop, chop" muffler sound...

We should patent it and we would make a killing...

 

[wjburken]

I understand all of your points, and you are certainly free to do whatever you want to do, and I support your desire to have some project work on your truck.

If all you want is the chop sound, I don't know of any other way to achieve it, other than a cam swap. Other folks on this Forum who are much more knowledgeable than me in this area will chime in. @Doubeleive @randeez @swathdiver @wjburken

I do want to correct you on your assumptions regarding the gear ratio change. In reality, the 4.10 gears will actually reduce the wear and tear on your motor and transmission, as the motor will spend less time in the low rpm's, where it is less efficient in load/rpms, and wasteful on gasoline. If you baby the truck, as you say, then the 4.10 gears will actually increase the longevity of the truck, AND improve gas mileage.

Regarding long tube headers, installed by themselves, they will do nothing, other than change the sound of the exhaust. An aftermarket muffler would be a better, cheaper, and easier installation alternative option, IMO.

If you want truck projects, then do maintenance projects on the truck to increase its longevity. At 280k miles, I would anticipate that there are several suspension related parts that could enjoy a refresh/replacement. Shocks/struts, control arms, ball joints, and all suspension bushings are all wear items that eventually need to be replaced.

In the engine bay, all heating and cooling hoses are likely on their last legs and should be replaced. Battery cables and ground straps may need replacement. All exposed electrical grounds could be inspected, cleaned and tightened.

Regarding motor longevity items, I don't know what your current oil pressure is, but if it is on the low side, you could replace the oil pump as a major project, and/or you could simply drop the oil pan and replace the O-ring on the oil pickup tube. If your oil pressure is good, then I would not recommend dropping the oil pan.

Hopefully, this gives you some things to think about, project-wise.

I will admit that I am pretty much a "keep-it-stock" kind of guy so I am going to be of no help with suggesting how to get some "chop".

If what you are looking to do is increase the longevity of your vehicle that you stated "...does not leak at all and runs immaculately." I would keep maintaining it properly. Keep your fluids (oil, transmission, differentials, power steering, etc) fresh by changing them regularly (Severe Service Schedule). Also by addressing any issues that do come up right away.

I think @Joseph Garcia gave you a good list of items to look at as well like hoses, oil pick up o-ring, etc. All of these will help keep unexpected failures at bay.