Project GatTagO

iTrader: (7)

I do believe that the blue springs were used in the LS9 engine and the LS9 cam has very similar specs to the LS7 cam.

Andrew

Jarren_b

correct, Its almost Identical

KW Baraka

iTrader: (7)

The "horror stories" you hear regarding aftermarket springs typically pertain to setups that were subjected to:

High lift cams
High RPMs
And springs with the wrong spring rate for the cams being used.

But pound for pound, most aftermarket springs with out-perform the GM springs.


BTW....on the SS Forum this weekend, a member was swapping out valve springs with a cam change.....and found a broken spring. He's the 2nd person I know of who had a broken spring (exhaust side w/.530" lift) from a 'never raced', stock cammed, LS3. Fortunately for him, the spring stayed in place and his engine still lives.

Again, though....best of luck to you.

KW

JHZ28

iTrader: (3)

I would think a 7.400 or 7.425 pushrod would work good

Jarren_b

Thank you, Im thinking 7.425. 7.400 seems a little too short

mOtOrHeAd MiKe

iTrader: (8)

I am in a very similar situation with my Procharged LS2 build in our TBSS. Stock LS2 shortblock, stock 243s with upgraded aftermarket beehives, stock LS2 head gaskets, LS7 lifters, and an LS9 cam. I am using a set of budget 5/16" 7.400" pushrods from Speed Inc. Evidently from the LSA powered CTS-V forums this is the simple budget solution.

Yes, there are "better" cams out there... but, factory driveability and reliability were the cornerstone of my build. Seamless until boost kicks in.

MuhThugga

There is more to a valve spring than just gross lift ratings. It is a factory cam, so you should be fine with the LS2/LS3 springs, but I would be inclined to install a fresh set for $60.

I would also install the cam and measure for pushrod length instead of trying to order the pushrods ahead of time. Shoot for .075" of preload. It also wouldn't hurt to step up to an 11/32 or 3/8 pushrod.

mOtOrHeAd MiKe

iTrader: (8)

Valve weight is also an area of concern. IIRC the LS7 and LS9 have lighter valves than a standard valve 243-headed LS2. Also if you are going to boost the motor you have to consider pressure on the back of the valve under positive manifold pressure which is going to dampen the effectiveness of a weaker valve spring.

These are the springs (PRC 1518) I chose to use for a little added insurance over an LS9-type spring: http://www.speedinc.com/shop-by-manu...pring-kit.html

Jarren_b

Once I go boost ill be sure to install a stronger spring because Im sure ill get some valve float. That is a ways down the road though. I will be installing a fresh set of springs. I have a set of 7.45 pushrods already from a previous build so hopefully after measuring, those will work. Kip fabre from Cam motion thinks they will be a good fit so hopefully all will be well.

Project GatTagO

iTrader: (7)

Thanks for actually tracking down some concrete information about the LS& cam base circle. I am looking forward to updates after you install the 7.450" pushrods.

Andrew

Jarren_b

No problem man. I have searched the internet far and wide for days looking for this.

Here is a message from Kip fabre from cam motion-

I just looked up a LS7 Cam Doctor on LS IV it said that the intake lobe lift is .330 and the EX is .328 if that is correct the tip of the lobe in in most cams from are .01 below the main cam bearing. If that is correct then the base circle on the intake would be 1.495 and the EX would be 1.499 Here is how we get that. Bearing is 2.165 - .330 -.330 -.01 = 1.495. This is what I came up with. You can't measure across the lobe with a mike because you will be on the lobe ramps that can through you off a little.
Awesome! thank you kip.

That makes my 7.450 pushrods even closer to being the perfect length by that math.

Stock 1.552-1.495=.057

Stock PR 7.385+.057=7.442

Thats only .008 higher preload

Seems like that 7.450 should be perfect

FU_I_AM_UltraZ

iTrader: (20)

Have to revive this. Wrong info everywhere about the ls6-3 springs! Ok.. So back when the LS6 cam was a popular factory cam swap before the LS2 even came out, the listing for the max list for the LS6 Springs .570! Not .560 or .550! Somehow over the years... People screwed up the info! Again... Ls6 springs = .570 lift !!!
You will have zero issues using factory ratio 1.7 rockers on ls7 cam and ls6 sprigs! The GM stg 2 and 3 LS6 Z06 cams were suggested to use the LS6 Springs. Stg 2 cam was about same lift as stock 02-04 ls6 cam. The stg 3 was maxing the springs out. The GM performance cam kits in Jegs years ago had the kit listed. I bet I have an old jegs somewhere with it!

FU_I_AM_UltraZ

iTrader: (20)

Also.. Yes. The ls7 cam is designed for larger cubed ls7 engine. But look at the article showing all the factory cams swapped into a lm7 ! The ls7 and ls9 made great #s for just a 5.3!
This is a great article of exactly what I just stated...
https://www.hotrod.com/articles/ls-cam-test-comparison/
Hell, cheap ls2 cam made great power for a 5.3 swap dd car! Even a heavy car etc bc the ls2 came with a tbss remember. iirc, the tbss has 4.10 gears. Idr if has a bump in stall speed for the tq convrtr.
Still, ls2, 3, 7 and 9 all made awesome #s for a 5.3! But with a larger lsa on the ls7 & 9... Power band is in higher rpms. So is the ls6 also. I have a ls6 top end with fast 78mm on my ls1 wa6... Power kicks in like a small turbo after 4500rpms. My rev is set to 6800. I beat the crap out of her. 80k miles on top end and ls7 clutch kit with 4.10 and great tune... Perfect street car. 305 or 315mm tires are an absolutely must with solid axle. I don't dump the clutch and is just barely enough rubber to handle the power. I recently acquired an ls2. Thinking ported heads and i have an ls7 cam laying around I got for cheap! $100 with lifters, trays and pushrods with just 12k miles on them! Of course gonna re-use the lifters and maybe trays depending what mine look like since bottom end has 180k on it. Trays were not replaced at 100k miles when i did the top end. They were still good looking and was in a rush to throw it together. Since i have an 85z with an empty engine bay... And 2 LM7s laying around... Its just to get it running cheap... Its getting a ls2, 6 or 7 cam with 243 heads and tbss intake and all the bolt ons. Still going to hang with a coyote with ease! Traction given lol. 85z use to have a monster na 383 carb'd sbc solid roller cam and the works. Was 581bhp and ran 10.98 @121 mph before being kicked out for zero safety mods 😆 However, was not dd friendly. I only play with lsx since 10 years now and nothing else. Well.. I do some mopar 3.6L v6 Pentastar stuff also... But i only own lsx vehicles.
But the 85z has th400 tci trans. 3500 tci stall and 3.73 rear gears. Even making just 370whp vs the 580bhp it had.. I'll be happy knowing the valvetrain will keep up with my lead foot without having to adjust valve lash every 50 miles ( even with a girdle i had to adjust more than i had time to make for it )

02 UltraZ ( real slp hood! )
98ws6
04 tahoe
85z ( soon to be lsx power)
Also going to pick up a 89 ta that will get a modded 5.3 also after the 85z is running.
Dream has been having lsx powered matching 3rd and 4th gen z's and ta's

G Atsma

I would never use an LS7, LS9,or even the late LS6 cam in a 5.3. Low end power evaporates in a small engine that needs all the low end it can get.
Most of the other OEM cams are OK. The early LS6 cam is better, and the late LQ4/LQ9 cam is a good upgrade over the stock one

bortous

Agree with "The G meter" here.
You don't want the ls7 camshaft in that engine.
It will have a crappy torque curve and it will want to spin high.

HioSSilver

iTrader: (8)

Probably the same info fu posted but in video form.

Darth_V8r

iTrader: (4)

Depends on goals. If you want a high revving 5.3 in a light car it can be a great option. I had the ls6 cam in a 5.3 in a suburban and hated it. Wrong cam for the application truck was too heavy and needed the torque. I always wished I had gone in and advanced it 6 degrees.

But not every engine is going into a 3500 ish pound street car.

FU_I_AM_UltraZ

iTrader: (20)

Why wouldn't you put an ls6 cam in a 5.3 in an f car? Bc of it lacking the .3x Liters? Why would that matter? If auto, would need matching stall converter and gears. If stick, would run fine with stock 3.42s. F car is still not a 4500-5k lb truck.
I really wish they had done added into the mix of other cams the lsx 454 cam. Has great looking numbers for a 6L with good heads and intake. Even stock ls3 heads.

G Atsma

Depends if you mean the early (204/211, .525/.525, 116LSA) or the more common late cam (204/218, .555/.551, 117.5LSA).
The early one would be good with the relatively narrow spread and narrower LSA, but the later one loses a decent amount of low end power with the huge duration spread and wider LSA.
It would work OK in a light car, but there are so many better cams.
The extra .4 liters makes a big difference in the effectiveness of the late cam.

Darth_V8r

iTrader: (4)

no reason not to, unless it comes down to preference. As I said, I didn't like it in my suburban. completely different animal, as you said.