jeepin Jeff

I LS swapped my Jeep JKU over four years ago. Have put about 60k miles on it traveling all over the country overlanding and rock crawling. The donor engine was a 2013 5.3 LMG, it was bored .020 and the cam replaced with a new Melling ‎MC1390 cam - 193 int./193 exh. 0.482 in.

I have had this jeep tuned several times and I have zero drivability issues except for one. It starts, runs and pulls around town great, can run down the interstate at 80 and pass people with ease and never overheats on even the hottest days on trail or off. But, when I start climbing a long grade in the mountains I can't make the top without it losing power and downshifting, from 6th to 5th then 4th with the engine temp rising quickly. I can't maintain any speed and if its a long grade I'm doing 40mph in 3rd gear and the heat will quickly rise to 230-235. Peaking the top and starting down the grade it will cool back off to 200 or less pretty quickly. I'm sure I don't have a cooling issue but I have come to the conclusion that maybe I just picked the wrong cam and have no torque at all, it just won't climb in the mountains.

I love this Jeep and would drive it anywhere but just got back from a trip to Colorado and I was ready to drive the thing off a cliff. Am I right in thinking that is just not enough cam for a 6000lb brick shaped Jeep?
Can I expect something like the BTR truck norris cam to improve the "climbability" issue I'm having?
Thanks in advance for any thoughts and opinions.

NAVYBLUE210

Cam Motion smallest drop-in 5.3 Stage 1 Truck Cam is 200*/204* 114*+3* .501"/.501"
(High Lift Version .527"/.527" is what I would suggest).
My .02

jeepin Jeff

Thanks for your input but I wouldn't mind something with a little more lift, have no issues with replacing springs. Again, down here on the flats of KS I never really notice a problem but I go to the mountains once or twice a year and this thing can't pull a hill worth a darn. I've just about had enough of this crap and need to make a change. I had kept the VVT when this was put together but think I will delete that this time around.
I'm not after a hotrod, I daily drive the thing and I would like a little performance and decent mpg if possible. Any other suggestions?

Full Power

FIRST thing: Install the proper Ring and Pinion ratio. Mouse motors need low gears, they like to SPIN.
I like the TSP cams, 208/214 .550 Lift works VERY well in a heavy Suburban.

LS1 TJ

My 98 Wrangler has a LS6/4L60E swap. Rebuilt LS6 with forged rods and pistons. Stock LS6 heads. Stock LS6 cam. Haven't had many long hills but it never over heats.
Maybe that 5.3 cam is a bit small. Maybe a LS6 cam? A larger radiator just to fix the hill higher temps? Maybe an upgrade to a 6.0?
But if do you have big tires and what gears? Big tires kill gear ratios.
Also as you are loaded down for a trip with a lot of "stuff" on the roof making an "brick" aero wise worse?
I haven't had a 5.3 in a Silverado 1500 for a number of years but when I did it down shift a lot on hilly trips out to MT. On cruise or on the pedal it would get back up to speed and then up shift. Shortly then as the hill pulled the speed down it would cause it to down shift again. I hated it.

68Formula

How big are your tires and what's your rearend gear ratio? They originally weight around 4000lbs and only had a 3.8L, so seems strange it's that under powered with a 5.3L.

You said you kept the VVT when you installed the camshaft. Are you sure the cam is compatible? Is it advancing/retarding properly? At cruising speeds (<3500 rpm) and lighter loads the PCM retards it to reduce pumping losses and improve efficiency at the expense of torque. Maybe try zeroing those cells. so it only retards at high rpm WOT?

jeepin Jeff

My gears are 4.10's which should be fine with 35's and I have the best aluminum swap radiator you can buy which is sold by overland performance with SS camaro fan that will cool it down very quickly, just not when struggling to get up a steep grade. I believe that cam is compatible, but I wouldn't bet my paycheck on it. The guy I bought the swap kit from also did my tuning and he tried to talk me into a better cam but not wanting a hotrod I just choose that LM7 and kept the VVT, I wish I had listened but hey, you can't unpoop your pants I guess.
Driving it to work everyday the thing is scary fast from stop light to stoplight and never gets hot sitting in the heat on a trail or out rock crawling. If I never went to the mountains (which I do once a year) I wouldn't have anything to complain about. Just got back and decided something needs to be done as I do plan to travel more.
would I expect much improvement going from the little MC1390 cam to the trick norris cam?
68formula, I would like to look into zeroing those cells as you recommended and I do have hptuners, but not sure I understand just what to zero, can you message me a pic of the section?

Bob570

What intake manifold do you have, and do you have long tube headers on it? Both of those things have a large effect on torque production down low.

I do think a bit bigger cam would help, but gearing down would likely help more.

Depending on how ambitious you're feeling, switching to a 6.0 or larger displacement engine would help a ton, especially if you were to stroke it out. Or hell, throw a roots style blower on it and make gobs more torque.

I have no idea on the budget or how much work you want to put in, just wanted to throw out some ideas that would make your setup work a lot better.

jeepin Jeff

I am using the truck manifold and ss trailblazer exhaust manifolds. My swap guy (Overland Perfomance) tells me that the 4.10's are perfect for this JKU with 5,3 and 6l80 swap. He has a very similar setup and says his doesn't get hot at all when driving in the mountains. I think the difference is the cam, I should have gone with what he suggested and although I would love to have the bigger engine I will probably keep this for awhile, its very dependable otherwise.
I don't mind a cam upgrade as long as there is a consensus that it will help.

68Formula

Sorry, have issues with the tuning laptop, so no software access at the moment. See post #51 that I'm talking about. It'll be under the airflow camshaft section. There's 3 baro tables labeled low medium and high IIRC. On the LMGs they all 3 tables are exactly the same from the factory.

https://ls1tech.com/forums/attachmen...bernie-vvt.jpg

jeepin Jeff

Thank you, that helps. I will figure that out and do a little testing.

Full Power

.
. Negative Ghostrider.. 4.10 gears are more suited to 31" tires or shorter, if you are doing ANY offroad work, or LIGHT Towing.
35 inch rubber is BEGGING for at least 4.56 gears, and 4.88 would be better if you plan to get in the mud, or TOW.
Only way to get away with tall highway gears is if you are boosted and have a loose torque converter, other wise life with a TALL geared 5.3Liter is going to suck.
.
. Your thread is asking about CAMS. NO Camshaft will solve a basic GEARING problem.

wlink14

No, you need gears. I have a friend with a 1984 S10 blazer with 35-inch tires, and it was a dog until he switched to 5.13 gears from 3.73 gear. It still drives down the road great with overdrive(you have double overdrive!). The difference was amazing.

jeepin Jeff

I have a friend with almost the same rig, he has 4.10s on 35's also and doesn't overheat climbing mountain grades. The difference is the cam I think.. When I swapped this almost 5 years ago the guy I worked with from Overland Performance told me not to use the cam I picked and that it would cost me power. That is why I keep going back to a cam upgrade. I was informed by him that the 5.3 with 6l80 and 4.10s were a perfect combo and based on his experience (they swap a bunch of them) 4.88's would be to low.
Would lower gears help? yep, probably would but I just wanted to get a consensus that it would or wouldn't help to upgrade the cam. Its about the most mild cam that could be put in a 5.3 I think.

LS1 TJ

IMO as said above I think 4.56's would make a big difference. You didn't say if you have a two door or four door. I would take your rig to a weigh station and see what it weighs fully loaded with all your overlanding stuff. I think you will be suprisied at what your rig weighs fully loaded.
Another thought over heating wise. What are your fans set at on and off wise. Could you reset them to come at a lower temp? Does one of the fans come on as soon you turn on the AC?

G Atsma

The mildest cam for the 5.3 would be the stock one. And for 4-wheeling it's pretty good, as you won't get more off-idle torque with anything else.
The above-mentioned Cam Motion cam would be the next best thing
BTW, your cam is the one from the "high performance" (yeah, right...) Gen III 5.3. It is a Melling copy of it.

68Formula

4.10s with 35s and a 6L80E should be fine. Seriously doubt it's the source of your overheating. My LMG/6L80E truck weighs 6k with driver, original cam (AFM disabled), 32s, and 3.42s (which is less effect overall gear ratio than OP's combo). I've towed 4500-5000+lbs @ 80+mph with an ambient of ~90+F it had no issues.

I'm not convinced the cam is the solution either, but the Cammotion mentioned, or Summit-8727R1 if you want to add a low-end torque camshaft.

Let us know how zeroing out the VVT tables below 4000 works out for you.

jeepin Jeff

I am looking into that but not sure I completely understand what to change yet. I do think that is a good suggestion that makes sense and am anxious to try that.
Thank you.

jeepin Jeff

Are you saying to set the desired angle low, med and high on all three tables to 0 below 4000rpm?

68Formula

Camshaft is "parked" in advanced position. Zero out the cells in yellow/orange below 4k. This will prevent the camshaft from retarding in that region (stays advanced). The reason those cells are retarded in the factory calibration, is to reduce pumping losses for better efficiency at a tradeoff of torque @ those loads/speeds (it can also increase exhaust temperature).

Don't touch the cells at 4k and above, as retarding the cam position in that region actually increases power and extends the useable rpm range (at least in the higher load sections). While your at it though, It would be nice to see that end of the table . I'm curious if that area is still same as factory as well since 4000-4200rpm values are equal. Although since it's only showing whole numbers the cells might be different past the second decimal point.

As you change elevation, you'll vary which of the low/medium /high baro tables you hit. That's why you want to modify all 3. GM elected to keep those tables same from one to the other on the GENIVs.