5.3 with LS6 Cam Push Rod Question
Thread Starter
Staging Lane
Joined: Oct 2010
Posts: 59
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From: Markham, ON
5.3 with LS6 Cam Push Rod Question I'm having a 5.3 block prepped. Deck heights measure good with a caliper and flat using a straight edge and feeler gauge so leaving them untouched. LS6 cam, 234 heads, LS7 GM performance lifters, stock rocker arms, LS2 GM springs, heads not milled. Need to order push rods. Machine shop dude says stock length (7.350") will be fine.
Any opinions on this?
I would use a 7.4 pushrod. There is over .050 slop either way in the stock ls7 lifters. They can get noisy when there on the short side. No big cam?
Last edited by handyandy496; Jan 4, 2019 at 05:40 AM.
I’d mill those 243s about .035” then use stock length push rods. The added compression ratio will help with the less than desirable cam shaft. That cam is high strung even in a 10.45:1 346” engine And usually only works well in the 5.3 when boosted.
Remember GM made the LS6 valves .0236” longer to help make up the base circle difference of the cam.
You will need 7.4” if you simply don’t want to machine the deck or mill the heads
Remember GM made the LS6 valves .0236” longer to help make up the base circle difference of the cam.
You will need 7.4” if you simply don’t want to machine the deck or mill the heads
If that 5.3 is going into a truck, I would strongly reconsider that LS6 cam. I did that in a suburban and hated it. Lost all its low end, lost 2-mpg, and I can tune pretty decent. Not a good cam for a lower compression engine. You'd really do much better with one of the vendor stage 1 or 2 truck cams.
stock pushrod length is 7.385 not 7.350. the 7.4's will actually measure 7.412 if you put a caliper to them. The 7.385 stock pushrods will measure almost 7.400 if you put a caliper to them. I would run the 7.4 x .080 BTR pushrods on that combo all day long. And consider the PSI1511 springs over the LS2 springs. Takes a pound out of your valvetrain, which will be great for control and a little extra punch to the throttle response.
stock pushrod length is 7.385 not 7.350. the 7.4's will actually measure 7.412 if you put a caliper to them. The 7.385 stock pushrods will measure almost 7.400 if you put a caliper to them. I would run the 7.4 x .080 BTR pushrods on that combo all day long. And consider the PSI1511 springs over the LS2 springs. Takes a pound out of your valvetrain, which will be great for control and a little extra punch to the throttle response.
TECH Senior Member
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From: Central Cal.
Unless it's the EARLY LS6 cam, which is the same grind as the LS2, the cam you are using will do the 5.3 NO favors except over 5k RPM. The early one is much better, but still not ideal. There are a BUNCH of drop-in truck cams that will pep up the 5.3 thru the whole rev range.
Thread Starter
Staging Lane
Joined: Oct 2010
Posts: 59
Likes: 1
From: Markham, ON
Thanks Guys.
My dyno program shows this cam as having great low end torque. However, this is just a computer program and your real world experience is good to hear.
I don't care at all about higher HP. Not going to the track and we lose out license temporarily and car gets impounded temporarily, if we go 30 miles an hour over the limit. I already have a stock stall converter. Looking for (as) good (as I can get) mileage with a nice running, smooth idling motor.
I have 3.73 gears, so that should help get it moving.
From anyone here that felt it was a dog down low, what gear ratio were you running? Not doubting, just curious.
Sorry about the big letters on the initial post. It was a cut and paste.
My dyno program shows this cam as having great low end torque. However, this is just a computer program and your real world experience is good to hear.
I don't care at all about higher HP. Not going to the track and we lose out license temporarily and car gets impounded temporarily, if we go 30 miles an hour over the limit. I already have a stock stall converter. Looking for (as) good (as I can get) mileage with a nice running, smooth idling motor.
I have 3.73 gears, so that should help get it moving.
From anyone here that felt it was a dog down low, what gear ratio were you running? Not doubting, just curious.
Sorry about the big letters on the initial post. It was a cut and paste.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
Just to clarify, which year LS6 cam is it? As I said, there are two. The earlier one is actually pretty good compared to the late one.. Or if you know the specs, put them up here please.
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Staging Lane
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From: Markham, ON
Intake Duration at 050 inch Lift: 204 Duration at 050 inch Lift: 204 int./218 exh. Intake Valve Lift with Factory Rocker Arm Ratio: 0.550 in. Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.550 in.
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Brett Foote TECH Senior Member
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From: Central Cal.
It's the late cam. You would be better off with a drop-in truck cam. FYI, the early cam is 204/211, with lower lift (about .525). Somehow all that exhaust duration does not agree with engines smaller than 5.7L
Thread Starter
Staging Lane
Joined: Oct 2010
Posts: 59
Likes: 1
From: Markham, ON
If that 5.3 is going into a truck, I would strongly reconsider that LS6 cam. I did that in a suburban and hated it. Lost all its low end, lost 2-mpg, and I can tune pretty decent. Not a good cam for a lower compression engine. You'd really do much better with one of the vendor stage 1 or 2 truck cams.
stock pushrod length is 7.385 not 7.350. the 7.4's will actually measure 7.412 if you put a caliper to them. The 7.385 stock pushrods will measure almost 7.400 if you put a caliper to them. I would run the 7.4 x .080 BTR pushrods on that combo all day long. And consider the PSI1511 springs over the LS2 springs. Takes a pound out of your valvetrain, which will be great for control and a little extra punch to the throttle response.
stock pushrod length is 7.385 not 7.350. the 7.4's will actually measure 7.412 if you put a caliper to them. The 7.385 stock pushrods will measure almost 7.400 if you put a caliper to them. I would run the 7.4 x .080 BTR pushrods on that combo all day long. And consider the PSI1511 springs over the LS2 springs. Takes a pound out of your valvetrain, which will be great for control and a little extra punch to the throttle response.
I will be placing an order for a trunnion kit from BTR soon. I could add the push rods at the same time.
Not sure of what my stock rod length is supposed to be, but they did measure out at 7.350.
I sure want to make sure they're long enough not to tick away.
My compression will be 10.5 minimum.
Did your 5.3 have the dished or flat tops? A Suburban will have a lot more weight than an El Camino for sure.
Everything comes into play.
A couple simulations below.
First one is LS6 cam.
Second is a couple of lobes from Comps list.
I will find some of these cams you mention, enter the numbers and get back with the results.
If that 5.3 is going into a truck, I would strongly reconsider that LS6 cam. I did that in a suburban and hated it. Lost all its low end, lost 2-mpg, and I can tune pretty decent. Not a good cam for a lower compression engine. You'd really do much better with one of the vendor stage 1 or 2 truck cams.
I run this cam in my 72 A-body wagon...It's ok, but as Darth says, you would be much better off with a custom grind, or any vendors truck spec cam...
The "5308" LS6/Z06 cam you have has a .050" reduced base circle...if you run the 7.35" pushrods you mentioned, your probably going to have a lot of the "sewing machine" noise you've read about. When I used this cam I ran 7.45" pushrods and it sounds fine. (ALWAYS measure for pushrod length.)
It is very soft on the bottom end. I run a 3.73 in the wagon, and am definetly going with a custom grind when I install the 6.0L.
Thread Starter
Staging Lane
Joined: Oct 2010
Posts: 59
Likes: 1
From: Markham, ON
I run this cam in my 72 A-body wagon...It's ok, but as Darth says, you would be much better off with a custom grind, or any vendors truck spec cam...
The "5308" LS6/Z06 cam you have has a .050" reduced base circle...if you run the 7.35" pushrods you mentioned, your probably going to have a lot of the "sewing machine" noise you've read about. When I used this cam I ran 7.45" pushrods and it sounds fine. (ALWAYS measure for pushrod length.)
It is very soft on the bottom end. I run a 3.73 in the wagon, and am definetly going with a custom grind when I install the 6.0L.
The "5308" LS6/Z06 cam you have has a .050" reduced base circle...if you run the 7.35" pushrods you mentioned, your probably going to have a lot of the "sewing machine" noise you've read about. When I used this cam I ran 7.45" pushrods and it sounds fine. (ALWAYS measure for pushrod length.)
It is very soft on the bottom end. I run a 3.73 in the wagon, and am definetly going with a custom grind when I install the 6.0L.
Don't have the cam yet. Still have time to run some more numbers.
The LS2 cam has horrible lobes. That GM cam test proved it. The late LS1/LQ9 cam was the best for torque response and mileage Aftermarket stuff in the 200-210 range are perfect for your application. To me even a free cam is no bueno if it’s the wrong cam
Thread Starter
Staging Lane
Joined: Oct 2010
Posts: 59
Likes: 1
From: Markham, ON
Originally Posted by A.R. Shale Targa
The LS2 cam has horrible lobes. That GM cam test proved it. The late LS1/LQ9 cam was the best for torque response and mileage Aftermarket stuff in the 200-210 range are perfect for your application. To me even a free cam is no bueno if it’s the wrong cam
Thread Starter
Staging Lane
Joined: Oct 2010
Posts: 59
Likes: 1
From: Markham, ON
Found one practically free, but the right one. A used LQ9 cam for for 15 bucks not far away. Is it worth an hours time to look at it?