All right here is what I've got an 89 L98 with iron heads and I'm currently in the process of switching to the Lt1 intake. My plan is to throw in a new cam, and do some mild head porting when I swap intakes.
I've pretty much narrowed it down to the Hot cam.

Now I plan on keeping the stock rocker arms for now. They have a 1.5 :: 1 ratio correct? With that my lift will come in at .492.

From what I gathered from old posts this will require some machine work to my heads to clear the valveguides. My question are what specifically, if anything, must be done in the way of machine work to the heads to accomadate this cam. And also if the valve guide needs to be machined do I then require longer valvesprings. I was planning on getting the LT4 springs from scoggin dickey, will they still work.

Thanks

 

i have the same dillema. i would like to put the LT4 cam into a set of stock L98 iron heads and have posted this question before with no straight answer. from what i understand, you need to go to a stiffer spring and also one that is a bit taller as well. the diameter of the spring will be slightly larger, so you will need to have the spring seats machined out a bit. if i am wrong PLEASE correct me and add anything you feel necessary.

 

The HC likes 1.6 rockers, you will not gain it's full potential if you don't use them.

Nasty_Bird_'90 is correct. Even if you kept the 1.5 rockers I am pretty sure you will have spring binding issues. Take them to a good machine shop and tell them what you are installing. They will set you up with the correct springs and do all the machining to make them fit.

 

You can buy springs that will fit in the seats without machining, that will take up to .600" lift.
You'll also want screw in studs.
As far as machining the guides,I'm not sure ,but I'm running an LT1 cam with 1.6 rockers,and ZZ3 springs. I had to install new retainers to keep from hitting the guides,and it looked like there was alot of travel left,but I didn't measure it...
I'm roughly at .477"/.490"lift...

 

how do you like the LT1 cam? dou you have a full list o mods/parts that were needed to get the prject fnished? thx

 

I don't remember what kind of retainers we put in ,but oddly enough I remember they were $32..I used my stock valves and the ZZ3 springs...
As far as the LT1 cam,it's an upgrade from the L98 cam and the car runs very good,but I got spanked by an LS1 Ram Air car a few weeks ago and I just can't have that..(lol)So I too am planning on installing an LT4 hotcam with my L98 heads and probably a Stealth Ram..
And like Omega said,take the heads to an engine builder and he'll know what to do....

 

I have the hot cam with aluminum L98 heads and stock 1.5:1 rockers. check out the competitor's "2300" springs, it's what I'm using, no machining necessary to make them fit. with this spring i'm right at 350# of pressure at full lift which is max recommended for a hydraulic roller.
http://www.competitionproducts.com/page24.html

you'll want to get screwed in studs put in and have your valve guides cut down, i had mine cut .050" which is enough but in retrospect i would have liked more like .080." Shop charged me $2 per guide.

Other than that, check your geometry cuz you might need a different length pushrod, i never thought to when i did the swap but I will next time i'm wrenchin on her.

 

Nice to see others here doing buisness with comp-products..Their prices are really hard to beat.I live about 20 minutes from their store/warehouse and buy all my stuff from them..Butch who takes phone orders and tech support,builds race engines and did all the machine work on my block and heads.In fact if you buy heads from them he probably put them together..

 

so to make the cam work, you got the competetors 2300 spring set, machined the valve guides down, and put in screw in studs. and i may need different lengt pushrods? will that set up work on iron heads too? stock L98

 

I didn't have to have screwed in studs put in because aluminum L98 heads had them from the factory, but yeah if I had iron heads I would have had them put in. You're correct on everything else, it'll work on iron heads.

Oh, one other bit of advice I can give is get a new timing set, preferably a true double roller and pay attention when you intstall it. On mine, there were two different dots on the crank gear and I lined up the wrong one with the dot on the cam gear which resulted in my intake valves hitting pistons and bending all my intake pushrods. oops

 

I'm building a '88 L98 with irons heads and the LT4 HC. I bought the TPIS ZZ9 springs for ~$130 and took it to the shop. They said NO machining was necessary. They said NOT to use the cups on top of the springs though? Whatever those are... I haven't been up there for them to show me yet. Other than that... they said they'll handle up to .550" now. I also have to use intake style retainers on ALL the valves. I'm gonna run 1:6 roller tipped rockers too. I'll post info when I get it together and running!