millathrilla63

New to the LS world and have been doing a considerable amount of reading on this website about build combos. But still have tons of questions. Doing a swap into a 1963 Nova Wagon (my first car), my goal with the car is to have a very reliable 400-425 hp. I want to drive cross county and would like to do the occasional autocross course with it, not competitively but for ***** and gigs. I have a kid on the way and want to make this a daily/weekend cruiser/road trip car for my family. Compression wise I was thinking in the 10.5:1 unless someone thinks differently.

I bought a used LQ4 from a 2000 2500HD with 165k'ish miles. I actually drove the pickup before the guy pulled the motor for me and it all seemed ok. Just like all my projects this is snowballing a bit. I tore the motor down completely and have the block, crank and pistons at the machine shop currently for short block rebuild. The motor came with the iron heads, 879 casting I believe, but I have been on the hunt for aluminum heads. I bought a set of used unknown condition 823 heads this weekend at a swap meet. I talked to my machine shop and he said he will not touch LS heads unless they change out all the intake valves, that and to clean them up and go through them would set me back another $400. I have a brand new LS3 intake sourced for $300 and was told I could get away with using the stock LQ4 injectors.

I talked to TSP on cam choices a couple times. I spoke with a John the first time who seem to really know his stuff and was super helpful. He suggested running their PKG3 kit with the 2.5 stage heads and a 224r cam($2K, I just can't justify right now) He said with the trans that i'm running (bone stock 4L80e, with stock converter) that is the most aggressive he would go and would fulfill my needs as a solid cruiser. He also said that I might be just shy of 400 HP too. I asked if he thought I should do a upgraded converter (2,000-2,500) if that would help but said for cruising he would not go that route.

The second time I called TSP, I talked to a Travis that seemed very short and not so much helpful. He suggested a 220R cam.

My questions are, am I on the right path to achieve my goals with the stock LQ4 long block with 823 heads and one of the above mentioned cams?

I've also read that 706 heads, LQ4, and mild cam is a good cheap combo and am wondering if I should resell the 823 heads that i'll have $900+ dollars into for some cheap rebuilt 706 heads. With this route I could save money on buying a different intake etc.

I have now been reading about Summit Racing cams, but am open to all suggestions

wannafbody

iTrader: (2)

Depends on what you want out of the engine. If you want quick response down low vs higher power up top then go for the 706 heads. 823 heads should make more power up top with a larger runner and valve. In between the two, would be a set of 243 heads which would only be down a few hp to the 823. Personally, I'd do the 243 heads.

G Atsma

FYI, 243 and 799 are the same head. Don't know whether you knew that

Ls7colorado

iTrader: (3)

Why are all these people buying low mile engine and tearing them apart?? Especially ones that ran/drove fine before being pulled!!!?? When did this become a thing again??

Anyways... like said above any of the heads will suit your needs. the 706/862 will give you more power until about 4000rpm or so and then the 823's will take over from there.
So if your not planning on revving the car or throwing a bigger cam than you listed above they will be just fine..

But if I already had a set of 823 heads and a Ls3 intake I would HAVE to use them! And why do the 823 heads need to be redone?? If all the valves are in and the combustion chambers look good I would just clean them and lap the valves a little bit when you change the valvesprings out for the new cam.
As for cam I would personally go a little bigger and run a 3500 or so stall. That stock converter will KILL your acceleration even with a stock cam. Even with a higher stall your cruising will be the same because the converter clutches will lock in once up to speed.

Know It All

This is what I would recommend. With the 823 heads, you're looking at about 9.8:1 compression without any milling. That is just unacceptable for an NA street engine.

On the other hand, the 706/862 heads are going to get you about 10.6:1 without any milling. That's a pretty good jump in compression which is going to add power and torque over abroad RPM range. I think that's what you are really going to like in a street driven cruiser.

millathrilla63

I would say that part of me regrets opening up the entire motor $$$$ and the other doesn't, as I want to put this motor in and not touch it again.

Would milled 823 heads plus right gasket get me to that 10.5:1 range and be a better head than the stock 706?

The extra cost with switching from cathedral to rectangular is just really starting to add up. I do not have the offset rockers yet, I've been told by many local guys that while i'm doing that I might as well do the bronze trunion kit in them. I'm just starting to question if all that extra money is worth the power difference in this motor combo?

Know It All

It's about 1cc for every .006" milled off the deck, so you would need to cut about .050" off the 823 heads just to match the 706 chamber.

I'm with the side that says the rectangle port heads are too big for anything under 400ci with a plastic (long runner) intake. I think the smaller cathedral head with the smaller chamber is perfect for a cruiser engine that you really won't be competitively racing with. I don't think it's worth it to mill the 823 heads because I see it as a waste of money and effort trying to make the inferior head work, but it's your money and it's your preferences.

Summitracing

OP, going off your initial post with the intended use of this build. We would recommend the 706 route and a "smaller" cam. We would sell off the 823 heads and LS3 intake. Use that money to get a valve job and bowl blend on the 706's. Total Engine Airflow (TEA) has a nice program for this. It consists of a competition valve job, mill, and bowl blend that is inexpensive and produces great power.

Our Summit Pro LS SUM-8715 "Ghost Cam" would be a great candidate for this. Specs are .600/.575, 222/233, 115+3. It's designed for stealth and driveability but also makes excellent power. It has a noticeable lope at low idle speed but turned up around 900 it will have a smoother idle. It will require upgraded springs. PAC 918's will keep the valvetrain happy. We have them through Trickflow TFS-16918-16. A 2500+ converter is recommended but not required. This combo would achieve your 400-425 hp goal.

There could be another cam if you wanted the curve and torque even lower. The Pro LS Truck stage 2 high-lift SUM-8720 could be of interest. Specs are .600/.600, 218/227, 112+2. This will share the same characteristics of the Ghost Cam just with a powerband moved lower. The earlier we close the intake the lower the curve will be. To compare, the Ghost Cam closes the intake at 43* ABDC. The stage 2 high lift truck closes the intake at 39* ABDC. The early IVC will sacrifice peak hp but you should be able to get your 400 hp goal with the 706 heads. The Trickflow TFS-16918-16 springs would pair well with this cam. A stock converter should work just fine with this cam. A 2500+ converter would be a plus but not at all required.

Either of these should net your hp goal combined with the 706 heads. It's just where do you want the powerband to be.

Ls7colorado

iTrader: (3)

I will trade you a set of lightly ported 706's for your 823's ill pay shipping both ways.

I also have a late model "Trail Blazer SS" intake that is the best flowing factory cathedral port intake with injectors, and fuel rail.

LLLosingit

iTrader: (4)

Op says it's 165,000 and has iron heads, Do you consider that low miles?

Ls7colorado

iTrader: (3)

car in my sig had over 300,000 miles from a heavy box truck on that 6.0

bigjohnjed

Lot of info here . The recommendations from Summit sound proven . But I haven’t seen anything about Tuning this combination. Even if you use what the so called drop in Cam . Bolting up stock set heads from a 4.8 has to change what the ECM is seeing . . Has to be addressed. In my opinion. then what pay someone to tune it . Do they really know how .
someone buys HP and says I can do it for 300 but it cost you even more when they messed up and blame your combinations .
Personally
my 03 2500 Lq4 is about to receive the summit drop in cam and a set of 706 heads lifters pushrods and either trunnion upgrade or rollertip rockers and I have HPtuners (which I am novice meaning never used ) but have programmed my factory programs I’ll figure it out . Thats why I’m here to learn from y’all . My main concern is longevity will it last if everything is done right .

mjmarinara

@Summitracing is that 400hp and the crank with accessories or at the wheels? Planning on a similar lq4 706 build and the summit cams are in the running.... want down low and early power for the street and a low maintenance valvetrain over my stock lq4 now thanks

Ls7colorado

iTrader: (3)

Im 99.99% sure they mean RWHP

gagliano7

mjmarinara

that would be amazing....been glued to richard holdener videos for over a year now...because of his finding i decided to go 706 over 799s because id rather that 12 below peak over the 8 after 6k

other cams in the running is the tsp stage 3 or 4 cathedral low lift truck cams, low lift yeah yeah i know but i really valve springs to last a LONG time because my swap is TIGHT...plus $400 with springs thats like sloppy cams cheap 216-220 .550 112 or 222-226 .550 111+3

kstanbach2

I would use the 823 heads, but your machinist is crazy, there is nothing wrong with stock valves. I would use the 823s because they make more power, and you have them. I am not familiar with the cams you posted.

jimmer1g

I just picked up a set of 706 heads for my 06 LQ4, I plan on getting the BTR stage 2 V-2 truck cam should work well for torque in my Sierra.

kstanbach2

I wouldn't worry about the compression. The difference there is like .25 horsepower. You can find rockers at the junk yard.

stockA4

The Torque pig 376

Here's my stock stroke LQ4 with all stock 706 heads. it's bored 65 over and it has silv-o-lite LS3 flat top pistons and sealed power LS3 rings in it on stock late model floating rods. The heads are bone stock 706 castec from a 2002 LR4 4.8L, they only have fel-pro head gaskets and valve seals with blue gm LS6 springs in them, The camshaft is a summit racing 8714 ~ 226/230 112+4 on the stock gears with a new LS2 chain, BTR 7.450" pushrods, LS6 intake and stock throttle body, Exhaust is old junk eBay headers and magnaflow F-body muffler.

The pull was made in a stock F-body with the stock converter 4L60E and 2.73 gears (pulled in second gear).

https://youtu.be/4iO9LgrVlHk