77volvo245

Michael Yount

iTrader: (1)

Representin' - nice!

G Atsma

Yep! Way to get it OUT THERE!

77volvo245

Here is an update: I blew up the original 4.8, spun a center main bearing. I bought a 5.3 engine, and while it was out we installed a cam. We bought the BTR stage 3 ls car cam. We had the car tune somewhat ourselves it's get to get it running and driving to the dyno shop. Here are the numbers

330 whp
320 tq
4l60e
17in 40x 235 tires
Btr stage 3 car cam
truck intake
Double valve springs with stock length pushrods

I have looked into the tune yet I might tweak at it some.

Michael Yount

iTrader: (1)

Do you have to remove the lifters to change the cam?

G Atsma

Not usually. The trick is to remove the rocker arms, and after removing the timing set, rotate the cam a full revolution or even more. This will make the lifters all ride up into the lifter buckets and stick in the "lifted" position. You may then slide the cam out, and the new one in.

77volvo245

Yes they will fall into the oil pan I learned the hard way, so the heads have to come off. They do make a tool so you can pull the cam out, without pulling the heads off.

Michael Yount

iTrader: (1)

I thought the LS motors had some sort of plastic retainer that held them in place if you rotated the motor with the rockers off....must be imagining it.

77volvo245

The plastic retainer only make sure the lifters aren't 90 degrees off.

G Atsma

But unless they are really worn, they "grip" the lifter enough to keep it off the cam lobe once their is no return spring pressure, enabling the cam to be removed once the lifters are raised by rotating the cam at least a revolution. Done many times by lots of guys without any problem.

Michael Yount

iTrader: (1)

What if, as is almost always the case, the new cam has more lift? How can you raise the lifter 'further' by rotating the smaller cam?

G Atsma

The lift can't be any higher than the diameter of the cam bearing journal. The way lift is gained is by reducing the base circle of the cam. So it would still work. The peak of the lobe is the same height as the journal diameter.

Michael Yount

iTrader: (1)

Ah - so longer pushrods always needed with the swap then? Thanks for learnin' me.....derail of thread over...

TipsyMcStagger

iTrader: (1)

I've only swapped one LSx cam and I did it while my engine was out of the car and on a stand, so I'm by no means an expert. I'd read about inserting dowels to prevent the lifters from dropping down.

But an even simpler method (as long as the engine is on a stand) is to simply rotate the engine upside-down and let gravity keep the lifters from dropping back down.

Tipsy

Michael Yount

iTrader: (1)

Wait - I'm about to confuse myself further. Of course, even the smallest journal is bigger than lobe peak -- which begs the question, how can you push the lifter out of the way of the journal?

Tipsy - while we haven't directly pointed to it - we're talking about a cam change with the motor in the car without pulling heads. Yeah - on the stand, everything becomes much, much easier for a variety of reasons.

TipsyMcStagger

iTrader: (1)

Yeah, I know. Just pointing out that inserting dowels seems to be the best way to protect against dropping a lifter when cam swapping with the engine in the car.

And using gravity is the simplest method when swapping on a stand.

Tipsy

Michael Yount

iTrader: (1)

Yup...

Any help past the question above - if lobe is smaller than journal as it always must be, how can the lobe push the lifter PAST the journal?

G Atsma

It just has to barely clear it, which it does. The peak of the lobe is almost ALWAYS the exact height of the bearing journal. You are the only one I've heard so far that doubts this. It works, believe me! NUMEROUS magazine tech articles demonstrate it to be so.

Michael Yount

iTrader: (1)

LOL - never doubted THAT it works; after all, I was the one further up in the thread that said “I thought the LS engines had some sort of plastic retainer....”. Simply asking HOW the lobe can push the lifter higher than the journal given that lobe is shorter than the journal. It’s a logical curiosity. Pretty sure there is some other/additional mechanism at work that hasn’t been described yet....

Nevertheless, let’s not derail this thread any more....seems no one here knows the answer. I’ll ask in the internal engine threads and report back.

BudRacing

iTrader: (3)

From what I understand, you use dowels to hold the lifters up. Good video to watch as a whole, but fwd to 8 minute mark to get to the point.