mattt

I have what started life as a 2004 LQ4 6.0 in a Yukon Denali disassembled and at the machine shop getting checked and ready to rebuild. It is going to replace an L59 5.3 flex fuel in my 2004 Tahoe daily driver with 315k on the ticker. I figured what was the point in dumping coin into the 5.3 when it's practically the same coin to do a 6.0. The block does need a bore oversize. This is a daily driver Tahoe that also handles towing duty for river and desert trips, as well as road trip duty. This is not really a hot rod type build but if it's putting down what an lq9 or even better, I'd be happy with it.

Is there any advantage to using lq9 flat top pistons vs. rebuilding with the dished lq4 pistons?

Compression ratio aside, which heads would you use on this, a 6.0 original 317 head casting or a 243 head casting? I have a set of both and know there is a CC difference in the chambers. CR can and will be figured and adjusted with head machining, piston selection, etc if necessary. Is one necessarily a better cylinder head than the other?

Planning on new oil pump, timing set, heads gone thru, gaskets/seals. Lifters must be replaced, correct? Machine shop says they can recondition the connecting rods for around $200.

I'm not sure what to do with the cam. I have the factory cam, but now is the time to change it if that is required. I live in CA so I have to pass the smog **** regs every other year, so that is a concern with cam selection.

Any other suggestions, advice, do's, don't's, please throw it out there. I'm all ears as this is my first LS build. Thank you.

68Formula

Flat top creates a more consistent flame front than a dished, especially if coupled with a zero-decking. This should get you a more efficient burn. Couple that with a quench distance in the .037 to .043 range (run ARP rod bolts).

My understanding is stock vs. stock there might be an advantage to the 243? But once the two are mildly ported, they're pretty equal.

If you're just looking for a something that will give you power across the whole range, play nice with a factory converter, and maintain stealth; the Cam Motion 6.0 Stage 1 Truck High Lift would probably fit the bill.

Ls7colorado

iTrader: (3)

Dont start with an engine that you need to take to the machine shop, grab a good running 6.0 thats clean and build off that. (or just swap it right in)

I maybe wrong but I cant see anyone wanting to spend 1500-2500 of unnecessary dollars on a engine to go in a 04 tahoe??

mattt

Thanks for the suggestion. CA is a tough market to come up on a good running 6.0. There are so many car nuts out here doing an LS engine in every project under the sun that good running 6.0's are few and far between and when they do come up for sale, they go for stupid money. I can have this core $400 engine checked and refreshed for less than a good running 6.0 can be purchased for. This engine I have may have been a "good running engine" but you just don't know??? So I made the decision to open it up and make it Great Again.

Also, unless the engine is in a running vehicle, how can a buyer be sure they are getting a "good running engine?" Most engines sold here locally, are already removed from the donor vehicle and you just have to take the word of the seller, which with the demographics in Southern CA, there are A LOT of dishonest people who do everything illegal including living here.

I will give you the point that rebuilding an engine for a 16 year old Tahoe doesn't make sense, but my Tahoe is in good condition. Interior is not thrashed, exterior is good - no crashes(Knock on wood) and I know the history on it. It serves my needs and I will probably drive it for road trips for another 15 years and/or 300k. I have considered buying a newer Tahoe, but let's look at the newer options..... 07-14 Tahoe's engine troubles abound, dashes crack, paint sucks. 15+.....paint really sucks, buffeting sound when driving. My parents have had both of the next 2 generations 07 & 15 and neither one of them has made me want to buy one. Add to that the cost to get in the door on a new Tahoe, yeah right....GM is smoking it! They can keep their overpriced $70k suv that starts having issues with 2-3 years. My 04 is still going strong. Seems like since GM took taxpayer bailout in 08 their quality has gone down. In my opinion the 03-06 generation was the best GM ever made. I have decided to dump a little money in mine vs buying a new jalopy. YMMV....

Ls7colorado

iTrader: (3)

Usually if you pull a valve cover and its fairly clean on a late model engine its good, and obviously make sure the engine rotates freely

I agree with you on the pre 07's being better than the 07-14 100%

Why does the block need to be bored?????

mattt

It was pretty clean inside, turned over easily, and had the golden color tinge internally that I've seen on other good condition engines. I'd just to go thru the process of swapping engines, having it all buttoned up and then discovering a problem with the 6.0 which means it would have to come out AAaagain.

Machine shop says the bore is out of service limit and slightly out of round.

From what I gathered online, the vehicle this lq4 came out of had at minimum 180k on the odometer according to a carfax type report I ran on the net for the VIN.

Ls7colorado

iTrader: (3)

Dang sounds like it was ready for another 200k miles

RichyB33

I did this a while back in my 03 Tahoe when the 4.8 threw a rod. I picked up a LQ4 off craigslist here in Albuquerque for $800 out of a wrecked truck. I changed to LQ9 flat tops and kept the 317s on it. I don't remember off hand what cam we used, but it was in the 214/220 range if I'm recollecting correctly. The truck runs really good. I don't tow much with it as I have a diesel for heavy loads, but it pulls my little camper and utility trailer just fine. All you really need to make "LQ9 power" is the piston change. I do believe that is the only difference between the two engines.

G Atsma

That is correct. Just the pistons, UNLESS you have an early LQ4 which came with the LM7 cam (191/190, .457/.466, 114LSA).
Once the LQ9 came out the LQ4 also got its cam (196/207, .467/.479, 116LSA).

mattt

It may have been....you just don't know when it's coming out of a pick your part junkyard. You may have been absolutely correct, I just didn't chance it and risk having to R&R it twice.

mattt

Awesome, thank you very much for the reply and info. You are what I was fishing for with this post. Wow!....$800 is a steal. That same wrecked truck engine here in Southern CA would go for ~$2400 and still have no guarantee. Cash and carry -no warranty- you own it. That is why I opted for an unknown condition long block and then have it gone thru to make it great again.

I have not decided yet whether to use lq4 pistons and the 243 cylinder heads or use lq9 pistons and stick with the 317's. Any opinions out there 243 head or 317 head for this?
I have a pair of both 317's from the lq4 and a pair of 243's that I picked off a LS4 5.3 engine. Whichever pair are used will be checked, cleaned, valve job, & bowl work by the machine shop.

I'd love to see this thing break/push the limits of a factory lq9 and be closer to 400 hp/tq but not sure that's do-able and keep it able to pass bi-annual smog checks here in CA and tow my boat to the river with ease. If you ever come up with the cam part # you used, I would be most appreciative.
Does yours have to pass smog checks there in NM, as I do in CA?
Did you have a custom tune burned to your ECU after installing the 6.0? I lean towards having it done on mine so things are all in tune and not running on the edge.

You are correct the only difference between lq4 and lq9 is the piston difference, which translates to a CR difference. Cam is the same according to everything I've seen/read.

Thank you again for weighing in on this thread.

mattt

I got word back from the machine shop that the block is ready. It ended up 020 over stock. Plan is to purchase the rebuild kit from WS6Store which I believe they said comes with Silvolite pistons.

Have a few questions to clear a few things up for a first time LS engine build on my part.
-Any problem with using the factory original connecting rods? Machine shop says they can re-condition them for ~$200 parts and labor
-Any problem using the factory original pushrods, lifter trays, rockers, hardware(other than tty head bolts), cam?
-Never consider re-using the factory, used lifters from what I've read? Correct?
-Is there a shop manual, book or other fool proof media I can take a crash course in LS assembly?

Thank you in advance for the advice.

P.S. If you have anything for sale of use here, please message me as I have not bought all my parts yet.

Ls7colorado

iTrader: (3)

If you have Gen 3 rods I would just find a good set of used gen 4 rods, "Reconditioning" rods I dont understand? there not a wear item so I dont see what can be done or what would need to be done. You can get perfectly good set of Gen 4 rods for under $100 shipped witch will be floating pin

If your rebuilding an engine it makes no sense to not replace the main wear items like lifters and pushrods, and makes no sense to not upgrade the camshaft either along with good valvesprings. I would even find a set of clean rockers off a lower mileage engine. In fact those items I would replace before I would even think about rebuilding a good stock bottom end..

mattt

The rods out of this 04 Yukon are what I believe to be Gen 4 rods, they are floating pin connecting rods. As far as reconditioning, the machine shop mentioned installing new bushings in the small end, and I'm not sure what on the big end. He did tell me to get rod bearings and say "010 and .002 housing." Are those just a slight oversize rod bearing? These rods can't be re-sized like a normal connecting rod, right?

Where would I find a perfectly good set of Gen 4 rods for under $100? I would definitely take that option if I can find it. Thank you for the info.

Lifters I have been heavily advised to replace and plan to. WS6 Store has a set of Topline lifters for $130. I guess I didn't really know that pushrods are considered a wear item too. Guess I'll be adding them to the list. Not really sure what to go with for a cam, which pushes me towards staying with the stock one. Since I have inspection requirements here in CA, I can't go crazy on that one and really don't want crazy for a daily driver Tahoe.
Thank you.

Ls7colorado

iTrader: (3)

Ahhh gotcha, if you have gen 4 rods then you wouldn’t need another set, I have never seen the bushing in them wear out though??

Someone else might wanna chime in on the bearing stuff I have only ran stock bearings.

Any stage 1 or 2 truck cam would be good and a good set of springs

mattt

Making progress on this. I got the block, crank, and various other parts back from the machine shop. Block is now 020 over, new cam bearings installed, polished crank. The Gen 4 rods are hiding in the box. Still undecided if I'll have them reconditioned for O/S bearings and new bushings installed at the suggestion of the machine shop. Have yet to order parts kit as well. I gotta get off the fence and make the call if I'm using lq4 pistons and 243 heads or lq9 pistons and 317 heads, as well as decide which cam is going to be used. Decisions, decisions.

Redbull87

iTrader: (3)

Run the 243 heads and flat top pistons and a very mild cam. Easy recipe for 400hp

mattt

I'm sure it is an easy 400hp recipe, but I'll bet it's going to result in a CR that isn't daily driver friendly for a ~5000lb Tahoe as well.

00pooterSS

iTrader: (40)

4.020 bore
Flat top pistons sticking out .005
.052 headgaskets (stock gaskets)
Nets 10.33:1 compression with 71 cc chambers (317 heads) and 11.13:1 with 64.5 cc chambers (243 heads)
Either can be done, cam timing and fuel octane will determine if it will knock. If you want to keep the stock cam I'd probably stick with the 317 heads.

I'd do the 243 heads, a mild cam, and 93 octane myself. But even doing the 317's and stock cam will be a huge improvement over the 5.3

As for lifters they are out of stock in a lot of places but ATK engines said they have a ton in stock and Thompson motorsports has some nice ones made for them that they say perform like more expensive lifters for a low price, I believe they are under $200.

Summit also has their own LS lifters that are supposed to be pretty good. And yes, do a new set. I would also do new valve springs, they wear out, throw some new stock truck ones in there or LS6 valve springs, LS6 valve springs are only $70. Pushrods should be fine, inspect them and see. Rockers kinda the same. This isn't a high revving application so a lot of this stuff can just stay as is as long as it's inspected and looks good.

mattt

Thank you everyone for all of the advice and opinions here. I need to choose which pair of cylinder heads to use and I'm tossed up between 243's and 317's. Valve size appears to be basically the same from what I read, maybe .025" intake valve difference? The plan is to get the CR where I need it thru piston selection and possible milling of the cyl heads.

Is there any substantive difference between using 243 or 317 cylinder heads if both have a little bowl work, surfacing, and are rebuilt prior to usage on a daily driver 6.0(not hot rod or race engine)?