I have received my LT4 HOT cam kit which includes 1.6 rockers, retainers, locks, springs, cam etc. My Brodix IK200s have springs that are rated for up to .575 lift, and the max lift for my cam is .525 at the valve with a 1.6 rocker. Should I use the springs on the heads, or should I use the included springs with the cam?

The uninstalled kit springs are part number 12551483 on gmpartsdirect.com. The description for them are:

This single valve spring is use on 1996 LT4 Production Corvettes and ZZ4 crate engines. Technical Notes: Single spring with 1.32" O.D. and 1.22" solid height. The pressure at installed height IS 101# @ 1.78" with 332# the average rate of pounds per inch. Use with retainer P/N 10168424.

The springs on the heads have a seat load of 130 lbs and 320 lbs average rate. If I dont have to, I really dont want to have to redo the heads since I bought them pre-assembled, but I need your opinions!

Thanks in advance.

 

In general, I'd personally tend to use the springs that came with the cam - you know that they're spec'd to work with that particular cam.

In contrast, the guys who make the cyl heads know that most people who buy those heads will use cams within a certain range, so (as a business decision) they have to use springs that can cover the widest range feasible, & it may or may not be what works best for your combo. (At least that's how it was explained to me.)

I'm in the same boat you are - bought my new heads fully assembled, learned that, decided that it's better (over the long term) to get everything in the combo right, instead of "crutching it" here & there...

Not especially HAPPY about it, but that's life...

EDIT: Looking at the two options you have, I'm not sure that there's enough difference between the two sets to warrant changing them out. Looks like the ones on the heads now have a bit higher pressure than is really needed (meaning that theoretically you'd be losing a little bit of HP if you went with them), but in the real world, I'm not sure whether it would be worth the effort of changing them out...

 

Barriing valvefloat, the whole valvetain will last longer with less valvespring load. There is just less pressure on everything. Depending on the lifter internal design and oil temp/vescosity there is a limit tohow much pressure a hyd roller lifter will take till it tends to run collapsed because the oil is being forced out by spring pressure. (noisy valvetrain)
Some radical hyd roller cams need max spring pressure and have to take it to the max to control the valves at very high rpm. If you want absolute max rev limit and are willing to take a slight long term component wear penalty, use the 130lb Brodix springs. If you want better valvetrain live and won;t be reving it to the moon, use the GM springs and retainers.
Many auto parts stores have a "loan-a-tool" program for stuff like spring compressors. Just check that the installed height is right with the GM spring and retainers. Some heads have nonstock long stem valves. +.100" is typical.

 

Those crappy STOCK springs that come in that kit are NOTORIOUS for breaking.

I would NOT use them, under any circumstances.

However, I don't know what Brodix supplies; so I'm not going to say, use those instead.

A good way to approach it would be to look at aftermarket cams with somewhat similar specs to the HOT cam, and use those. Comp 986 or 987 for example are the recommended ones for their cams and are known to work well with that little mild GM stockish cam.

Another possibility nowadays, is the new "beehive" springs.

 

Hey great news! I did some searching around, I found a spec page for the springs Brodix uses on their heads. All of their springs are Supplied by COMPETITION CAMS, ISKY, GAERTE, K-MOTION, and MANLEY. I checked for the IK200s and the springs that are used are the CC 987. The specs I posted for them above are a little off since they are the measured specs for the springs, but are only 5 lbs off from what is listed.

With this info, I think it is best for me to go with what is on the heads already.

You can check out the page here.
The IK series spec page is here.

The cam may have come in a stock engine at some point, but it fits my build perfectly