Picked up a clean 07 classic 2500HD for cheap this week. Has 164k on it and was deemed to need a motor, popped the VC and found a bent push rod and broken spring on the exhaust of #5. Swapped a spring I had on some old heads and a parts store push rod. Seems to run good now but I'm thinking about doing a head, cam, tune on it in the near future. It will be used as a truck, hauling trailers, material etc, so torque down low is my main desire. I have some 799 heads I was thinking of getting cleaned up and checked, throw some springs in them and swap the 317's out. Might do long tubes and ORY through stock muffler and tail pipe. It's 2x4, I need to check the rear end ratio, currently has stock 245 tires, will eventually step up to 265's most likely. Don't have a desire to change the torque converter. What would you all recommend for a cam? I'm more concerned with torque and performance, vs a noticeable lope. Will putting the 799's on push me to needing to run premium or would that more be dictated by the tune? I don't mind putting in mid or high grade if it's warranted and the power and reliability is there.

 

PM the guys at tech@ws6store on here. This build is right in their wheelhouse.

 

There is a huge number of truck cams out there from Brian Tooley, Texas Speed, Scoggin Dickey, and CamMotion out there. I would go no bigger than 212/218,.550/.550 or so, with about 114 LSA.
799/243 heads on a stock LQ4 will get you 10.07:1 compression.
If tuned right, regular unleaded is still doable. Gen IV 5.3 engines are all 9.9:1 and use regular with no issues.

 

Thanks guys, I'll do some more research now that I have some sort of direction, cam selection is by far my weak point in engine fundamentals. A year ago when I picked up the GMC in my signature I pondered and just picked a low lift TSP unit without really knowing or understanding the difference between a "low" and "high" lift cam. Do the other cam guys make high and low lift truck cams, and if so, what is the difference and or benefit of one over the other?

 

Im going to do almost the exact same thing only I will be using 706 heads.
Ls6 springs
stage 1 truck cam from summit or callies (180-009) 210/218 on a 108 lsa for a little lope :-)
long tubes
07+ (Tbss) intake
BUT I would consider running premium while towing heavy, especially when the outside air temps are high.

 

What is the difference of a 706 head vs some 799/243s? Is a TBSS intake also better for low end torque over the stock truck intake and would it just be bolt up and go deal or am needing injectors, rail etc etc?

 

I would do the 706 heads myself.

Richard holdener has a dyno testing video that shows the differences. Smaller chambers increase compression, Ports and valves favour low speed torque.

 

The 706 heads (or 862s) are 5.3 truck heads. They don't flow as much as 317 or 243/799s, but they have a smaller combustion chamber (5.3 heads are ~ 61, 243/799s are 65, 317s are 71cc). In the end, in a mild engine, the 5.3 heads usually will make more power/torque across the board, because of the compression. (a 243 head will catch up at ~6000rpm) I would think it would be a good idea to run higher octane if towing, if you are raising compression.

This thread has a ton of thoughts on the same topic.

https://www.performancetrucks.net/fo...intake-556378/

I have a TBSS intake on an LQ4, its not exactly plug and play. They are LS2 intakes, so the rails and injectors are a different height than truck stuff. The injectors are either 27# (or TBSS) or 33#(cars) The throttle body is 4 bolt, not 3 bolt like the earlier gen 3 motors. And there is no throttle cable bracket. None of that is a big deal. If you can get a complete intake, its not hard. And you can use a 3 to 4 bolt adapter to reuse your current TB. The TBSS in general makes more power everywhere, but dyno testing is usually showing 3000rpm up.

There are a bunch of very specific videos on this topic on Richard Holdener's youtube channel.

 

I have the 799's so that's why I was leaning that way, plus they are already smaller chambers than the 317's and raise the compression a point. They are off a 195k mile 5.3 so I'd have a machine shop clean em up and check them over regardless. I could probably score a set of 706's from a the junk yard for about 120ish for the pair after pulling them myself, then have those gone through. But that's my time and 120-130 bucks, would it really be that much I'm leaving on the table for a truck application when cost for benefit is applied? A quick google search shows mixed info on a 799 vs 706 comparison as being worth it or not. I'm not looking for peak #'s, just more torque down low without going all out. Again if it's going to be worth significant torque off idle to say like 5500rpm to go 706 and TBSS/NNBS intake vs stock lq4 intake and 799's with whatever cam I go with then I guess the juice might be worth the squeeze but I'm still not 100% sure another couple hundred bucks is necessarily worth it. But that's why I started this thread, to learn and get peoples information and opinions.

 

Check Richard holdener's video for actual results.
You could sell the heads you have for more than the 706 heads will cost you.

 

I don't know that its worth worrying about it, if you already have the 799s. You can have them milled a little to bump compression up anyway. Looks like the 799s are about 10 ft-lbs down at the low end, and catch up at redline. Milling the 799s a little and doing a good valve job would be just as good or better.

 

Funny thing...I have three of these. Just bought this last one to learn HP tuners on...kinda interested in what everyone thinks in this thread also...

 

OP will need to watch out for high compression. He specifically stated the truck will be used for towing and hauling. And the truck is already heavy to begin with and likely has a 4 speed and low ratio rear gears. So it's gonna drag out gears and need to watch compression.

Based on that and the fact he already has 243's, I would go with the 243. With the 706 heads and the cams recommended you're going to need to watch your dynamic compression, could end up needing premium at all times and be close to the knock threshold. I would prefer a little cushion for towing on hot days in this application.

Most guys with 5.3's stick to no bigger than 212/2xx cams in order to retain the stock torque converter. You can go larger since you have a 6.0. Keep in mind a 5.3 stock cam is a 190 degree duration cam on the intake and guys go up to 212 to retain low end. The 6.0 cam starts at 200, so 10 degrees more, and it's fairly applicable that you can go about 20 degrees too before you start getting into low end trade off for top end. There's a lot more to it but that's the general info.


Is that an LQ4? (dish piston 6.0)?
If so going from 317 heads to 243 (unmilled) heads would take you from 9.4 to 10.06:1 compression. I would do ws6 store .045 headgaskets (to help raise the knock threshold a little by lowering the quench) and will also bump compression to 10.22:1


I think you'd still be okay running the 706 if you chose to, but you'd be at 10.5:1 with stock headgaskets and 10.65:1 with .045 headgaskets. Which isn't horrible but it's getting a bit up there for a 6-7k pound truck that also hauls loads around.




As for head flow, yeah the 706 have smaller ports and some like that for torque, but this isn't a 5.3, it's a 6.0... it'll love the 243's

@Summitracing is really good with all this stuff, what do you recommend for OP? I know y'all have some cams that would be perfect too.



.

 

Thanks for all that info guys, lots to digest! Yes, this is a lq4 (dished pistons,) 4l80e, 2x4, ext cab short bed. I need to read the RPO codes to verify rear gear, it might be 3.73's as it doesn't feel as peppy as the 4.11 trucks I've driven, but maybe it's just been a while. My 5.3 1500 has a TSP low lift 212/218, .550/.550 cam in it. It's peppier than the stock DOD set up, but it's also just a 5.3. Pooter makes a good point on the 706 vs 799 debate with being close to knock threshold. The truck will be used as a truck and pull a trailer loaded down with my car, or a tractor, construction supplies etc, so it will be used, so some built in "cushion" would be nice. Plus then I don't need to spend time at the pick a part as my new place I just bought is no longer super convenient to there. I have a good machine shop that I can get my 799's cleaned up with a good valve job and even mill them vs just clean em up if the consensus seems to think it would be a good idea while there.

 

If you plan on doing lots of hauling/towing and are willing to put in premium, then stick with the 799s and the TSP Truck Stage 2 high lift. That'll put the power right where you want it, but you can still tune it on pump. Get a mild torque convertor and some 3.73s or 4.11s.

 

Since it is a 2500HD, I would bet he has 3.73's already. 3/4 ton trucks have decent gears.

 

I think your plans all sound good, and putting the long tubes on with a nice y pipe and a good straight through muffler should really help out as well.

I would absolutely do a 93 tune on it for max grunt (can really start dialing up timing and low end with higher octane).. not that you'll need to run 93 all the time, but I'd tune for it so you can run it on the days you want a little more power.

On my 2004 lm7 truck... it got 2 more mpg on 93 than it did on 87, so that's also something to consider

My current truck gained 2 mpg from a free flowing catback so I think all things considered your build will net you a lot more power and mpg.. win win. Well the cam may eat a little bit of it but shouldn't be too bad if you keep the overlap down.

This may be a situation where you should get a custom cam from cam motion

 

Yeah, check the RPO in your glove box. I'm interested also. 2 of mine were 3.73's, this white one was ordered with 4.10's...

 

I'll pull up the RPO's on Monday and figure out rear gear then try to source some long tubes and y. I was impressed with the fitment of the speed engineering long tubes and ory on my 08. I'll probably look to them again for this build, unless someone has some recommendations for something good without breaking the bank. They have two sizes for the primaries though, 1 7/8 or 1 3/4, which would be the better option for my intended use? After I get all the info on the table I'll call Cam motion for a recommendation. Also, I'd like to keep the stock converter for now, I've heard mixed reviews on towing with an aftermarket converter, some say it sucks some don't notice it all, but if it's not going to be a necessity I'd like to avoid it, at least for now.

 

Depends on the cam choice. But given your goals, sounds like you'll be somewhere between a the Summit Truck Stage 1 8719R1 and the TSP Truck Stage II 5.3. In which case, the 1 3/4" are plenty for your combination. So you'll have more low-mid range torque than you would with the 1 7/8" primaries, without leaving any additional peak horsepower on the table.

Now if you were building a stroker, boosting, or looking at a much bigger cam to push more mid to high range rpm (at sacrifice of low-end), then the larger primaries would be a better fit. If you were thinking about going down one of these paths later on, you could just go ahead and use the larger now so you'd have room to grow.