does anyone know if the LT-4 cam will fit in my 91' Z28 L98, with stock heads, and motor without any other modifications? In other words, can I take the old cam out, put the new one it, put 1.6 rockers, and take it down the tracK? Or do I need to have my valves machined to take the extra lift? Does anyone know what the maximum lift is for the cast iron L98 heads? This information is really important to know...and i guess I've over looked it in my cam shopping....Any adivice is helpfull..thank u.




Zach

 

I would NOT use the stock springs with that cam. Get the springs that match that cam. The valves will be ok as long as you use the proper springs. Otherwise you're going to get valve float at high rpms and really mess something up. Also, I believe you need an aftermarket, custom, or you own burned chip to make the engine run right with that cam.

 

Well i planned on upgrading the springs...and I have an ADS superchip...is that enough? Where can I purchase the LT4 kit? And a good spring/seals kit?

 

I found a kit on a site that sells GM perofmance parts, and they sell a kit that comes with the LT-4 HOT CAM, 1.6 roller rockers, springs and retainers.....would this kit pretty much put me in for a working combo with no other modifications to my motor to make it work...here is the site.
http://www.performancess.com/
wait for it to load and click on the GM performance on the left.


Zach

 

Well, it seems that this question is asked daily.... I want to point out that there is a search function on this site and it works fabulously (hint: do a search next time! ).

As stated above, you MUST change the valve springs to run the LT4 Hot Cam no matter the rocker ratio. I know that the stock iron L98 heads will take the LT4 HC with 1.5:1 rockers ( .492" I/E ), but I am not really sure if they will take the lift of the LT4 HC and the 1.6:1 rockers. And even if they did allow you to run that much lift ( .525" I/E ) , the crappy port design and small valves of those L98 heads won't make much use of it.....

Other than the lift issue, the cam is a direct bolt in for all roller blocks with pushing in the dowel pin on the front of it the only mod required on non-LT1 engines.

 

Will my motor benifit with the 1.5 rockers and that cam? Or do u know of a better cam/rocker combo to go with for my current mods/setup....I am just looking for a good way to spend this tax money....thanx for your help Mike!

Zach

 

Well I do have to say that your car seems to perform quite nicely for a mostly stock L98!! Very nice!

I think the LT4 HC will help performance on your engine some, but it really is designed for an LT1 style short intake runner setup and the higher RPMs that that intake manifold works well at compared to a TPI setup. So I really would look at some other cams with a little less duration than the LT4 HC if you are going to keep the TPI system and the stock heads.... The Super Profile L98 or L98 cam from TPIS is a little better suited to a TPI setup.... Just remember that it all works together and if you get a cam that makes more power but at a higher RPM than the intake and heads are designed for, it might not add any power at all..... or worse yet, make less power since the system could end up mismatched.

As an example, I put that cam in my car knowing full-well that I need a better intake system to realize the full potential of the cam, but I also put much better flowing heads on the engine. I had planned on getting a Miniram for my careventually to match the cam better, but now I am thinking about doing an LT1 intake to save some cash..... Either way, the bottom line is that I am keeping my eye on matching the intake design to the camshaft's design....

With your car running as strong as it is with the minimal amount of mods you have, I would look at maybe porting the intake plenum out and picking up some better runners, like SLPs, and porting them out as well..... A higher flowing manifold base will also help.... But watch how much you spend on TPI stuff, as you might be able to get a Superram or Miniram for the same cash and have much more potential in the long run.....

Exhaust is going to be important to get your car faster..... It looks like you have it under control with a Flowmaster muffler, no cat and headers, but which headers do you have? If you are running the Edelbrock TESs I might look at upgrading them to bigger shorty headers like 1 5/8" or 1 3/4" SLPs or maybe going to long tube headers like the Hooker Super Competitions......

Well, there is some stuff to think about.....
Hope that helps some,
Matt

 

The headers are just flowtech for all I know, but they have held up there color really well...Dont know the exact messurments, and u are right, not many L98's run what I run with the mods they have...U listed everything I am currently doing...I am going to order SLP runners to port, I have an extra stock base and plenum that's been polished, I will port both and port the SLP runners, the only thing I will pay for in that setup is the runners...becuase it's my friends old unit that he let me use as long as I give him my stock that I take off....But I guess I was just wondering what 2 do with this extra cash....and a cam came to mind becuase of the porting intake.....but I am up for any suggestions.


Zach

 

Yeah, I think if I were you I'd go with those runners, and maybe a siamesed intake. Then you would POSSIBLY breathe good enough to run that LT4 hot cam. I'm kinda in the same situation... building a L98 and can't decide between porting my stock iron L98 heads and running the ZZ4 or LT4 cam or going to a vortec head/tpi intake setup with the hot cam. Too many choices, not enough time/money. lol Also considering a LT1 intake yet too