Max

I'm planning a cam swap this spring. From what I understand it looks like the LT4 production cam may be a wise choice for my combination.

Now that I have 3.73 gears and the tunability of a Holley carb I'm thinking that a cam this size would be a good choice.

203 I / 210 E @.050
.476" I / .480" E Lift with 1.6 rockers

The lift would of course be less if I were to reuse my stock 1.5 rockers.

The questions I have are:

1. Can the stock LO3 heads handle that much lift without any interference problems?

I would probably upgrade to the heavier factory Z28 valve springs.

2. Can the cam be used with the original 1.5 rockers?

In the product description it says designed for use with 1.6 rockers. It also describes the cam as:

"an excellent power adder for 1987-95 TBI pick-ups and TBI/TPI cars"

3. Would this provide a good bang for the buck at $173?


I know that the stock LO3 heads will be the limiting factor in my combination but for right now that's what I plan on using.

Any advice will be appreciated.

Max

Just wanted to move this back to the top of the page.

Sitting Bull

Those specs sound like an LT1 cam, not the LT4.

Lt1s are supposed to work very well, even with the stock computer programing. But you should upgrade the valve springs to whatever Crane or Comp would recommend.

Max

Those are the specs for the LT4 production cam not the LT4 Hot Cam. It is milder than the Hot Cam and is similar to LT1 cam specs.

So you don't think that it has too much lift for the LO3 heads?

Max

Anyone else care to offer an opinion?

Sitting Bull

Only if you use the 1.5 rockers. 1.6 will cause collisions

ME Leigh

You need much better springs, stock suck.

Max

Thanks. So, if the LT4 production cam has:

.476" I and .480" E lift when installed with 1.6 rockers
(as it is described in the GMPP catalog)

Then I suppose it would have:

.446" I and .450 E Lift when installed with 1.5 rockers

Do you think that this is just about the maximum amount of lift I can use with the stock LO3 heads without interference?

Also, do you mean that any more lift would cause the valves to impact the pistons or are you suggesting that there would be another sort of interference problem?

I appreciate you help.

Max

just wanted to move this up to the top of the page

Sitting Bull

Not valve to piston but coil bind. So just 1.5 rockers and new springs.

NTChrist

I know the coils won't bind at that low of a lift (there are guys running LT1 cams with 1.6 rockers on L03s no problem) with the stock springs, BUT it's definitely not optimal.
I imagine valve float interferes with any higher RPM hp pretty badly.
And to answer your q's from your first post:
1) Yes
2) Yes
3) Yes. But, keep in mind that a used LT1 cam usually goes for about $100 USD.
I managed to pick mine up for $90 USD and it came with the roller lifters out of the LT1, too. Just something to keep in mind if you're on a budget.

BronYrAur

iTrader: (1)

If you plan on sticking with the 1.5 rockers why not just run the LT1 cam it actuallly will have higher lift than the LT4 cam will running 1.5's. I've also heard that the LT4 cam will not work to its potentiall using 1.5 rockers because it is designed to use the higher life that 1.6's give it, just my .02.