i have an 87 iroc 350 tpi. i am looking for a cam. i want a cam that has a noticable idle. i don't want it really choppy but i want something between fair and rough. i have been thinking about a cam with a lift around .500 but i don't know if that is a good size or not. i don't want to go to big because my heads will be stock for some time. i will program the computer though. it won't be a daily driver but i will drive it a couple of times a week. do they make a hotcam kit for this car like they make for the lt1's? i know they make a kit for the lt1's that sounds like a good deal. i probally am looking for a rpm range only up to 5500 or 6000 because i have stock engine. help would be great. thanks

 

The LT1 kit will work on your car, BUT, you will require head work for any lifts over .480" to aviod seal-to-retainer contact. You'll need the valve-guides machined down a little. This goes for any decent cam.
I'm going with the ZZ4 cam, a little milder than the LT4 HotCam, but more streetable and not far off in power.

 

so i can't run a cam bigger than .480 without head work? i was looking at the zz-9 but i wanted a little bigger. i was planning on leaving the heads in for now though. not sure what to do now. i am going to replace springs, seals, and retainers also.

 

Play it safe and stick to .460. An LT1 cam has those specs but be sure to stick with 1.5 rocker arms.

 

o boy, this is pretty surprising. i did not know any of this stuff. i was going to get the hotcam kit if it worked. in this kit was going to get 1.6 rockers. i know i probally would need new valve covers but that is not a problem. why do i not need to stay with a small cam with an lt1 but i do with a tpi? i know there are guys running cams bigger than .510 lift with an lt1 with stock heads. thanks

 

I'm not an expert on the LT1's but I know some people that run large cams on stock heads that are hitting the seals and don't realize it, and can't figure out why they don't have the power they were expecting. And it can lead to bent pushrods prematurely worn out cams etc.
Remove a valve spring on your stock head and with the valve closed and retainer reinstalled, measure the distance from the bottom of the spring retainer to the top of the valve seal and you'll understand. Figure in the safe .010" distance between coils or .050" usually. Some use .000" and things get loose, then bent or broken...
You can get heads modified for high lift for around $160 on average.
Valve covers are more of a problem b/c of the centerbolt design hitting the fatter "roller" rockers than lift issues. Converting to "perimeter-bolt" covers or using thinner "stamped-roller-tip" rockers should eliminate that problem.

 

OK, the standard GM heads (like your L98 heads) are safe for lifts up to about .460. Then they will get into rubbing parts together and that is not good for your engine. This problem is exacerbated if your use 1.6 rocker arms because they affectively ad around .030 of lift to the original with 1.5. That would mean your lift on the exhaust valve, for instance, would then be .490--WAY beyond the head's capabilities.

You can have your heads machined for wider and taller springs but that will require you to remove them from the engine and spend more money.

So my solution is to use a cam that will work nicely within the peramaters of your heads as they now exist. An LT1 cam has lifts of about .450 on the intake and about .460 on the exhaust. Moreover, they can be found on eBay for about $50. Compare that to a Crane or Comp, which run about $250.

You won't get a lot of lope at idle but that is only a sure fire sign that the engine is having a bad time running at that rpm--believe it or not!