I have an lt4 hot cam that has been sitting aroung for almost a year now and was wondering if putting it in would give me any performance gain. I have a 350 tpi GM crate motor that i just installed. it has about 20 miles on it now. other mods are listed in signature. is it worth it to install this cam with just the minor mods i have done? I do plan on doing lots more in the future to the top end. what other mods are needed to run this cam.

 

The LT4 Hot Cam will definately give you a gain in performance!! The stock cam is very tame and even if the heads aren't worked over, the rest of the mods you have will allow that cam to make more power than that stock cam is making for you right now. Plus, if you slide it in now, it is one less thing that needs attention later on if (when) you get better heads.

If you run the cam without changing rockers, you will need to change the valve springs as the factory ones will only allow around .490" lift and the LT4 HC has about .492" with 1.5 rockers - too close to live with, IMO. You should double check the retainer to valve guide tower (with seal installed) clearance as well.... Otherwise it will bolt right in with pushing the dowel pin in a bit on the front of the cam being the only mod required.

EDIT: Oh, and plan on having the PROM reworked or getting into burning your own PROM if you run that cam.

Hope that helps a bit....
Good Luck,
Matt

 

If you decide to not put it in, I'll buy it from you. Lemme know, thanks. bors1515@kettering.edu

 

I have everything in the hotcam kit except the rockers. I plan on getting 1.6 rollers before the cam install. I have a stage 2 ed wright chip. i do not know how to reburn the chip. do i need special tools to put it in or measure things

 

Your car will probably be slower than it used to be off the line but when 3000RPM comes around hold on to the steering wheel tight. It would probably be a good idea to get a higher stall torque converter. The LT4 HC makes power way above the RPMs TPI will allow so you should also probably port your plenum and get some aftermarket runners (at the least) so you can rev higher cause this cam will pull hard well over 6000RPM

 

Well,a TC wil be usless since i have a t56. i am running 3.73 so that might help get the car off the line. i did port the plenum, runners and base.

 

Whoop. Guess I can't read. The cam will still probably be a little bit out of your powerband but for the price I dont think it can be beat.

 

I have one in my 383, very strong on bottom end and midrange, no topend whatsoever. The topend is limited by poor heads and manifolds, but that is for later. You will notice a big difference if you stick it in there, but I don't know for sure what r.p.m. range it will occur at. Good luck!

 

Is the crate engine you just installed a late-model 87+ roller cam engine with a one-piece rear main seal? If its an 86 and earlier flat tappet cam engine, the LT4 HOT cam wont work.

 

How driveable will be the car with the LT4 hot cam. I'd like to get
one for my every day car.

 

Its extremely drivable. Has a little lope to it but nothing the average person would probably notice.

 

Well... I wouldn't say people won't notice the lope.....

Mine lopes pretty good:

http://www.mnfbody.com/memberpages/m...ndQuickRev.wav

I have 1.6 rockers on it so the lift is up there a bit ( .525" ), and the idle is set on the lower side ( ~ 650 RPM ), but it will still be noticeable to most people that it has a hotter than stock cam in it.

 

Matt, is it pretty easy to put a cam in. Doi need special tools to put it in along with the rockers and springs and stuff

 

Only special tools I would recommend would be a torque wrench, a harmonic balancer puller/installer, and a valve spring compresser.

 

Wow that sounds a lot meaner than my friend's S10 with the LT4 HC. His idle is around 900RPM though.

 

Like Rezinn said, you will want a torque wrench for all of the bolts that you have to tighten.... The Harmonic Balancer will need to come off so a puller/installer will be needed for it.... If you are changing valve springs on the car you will need to have access to pressurized air to fill the cylinder with to keep the valves closed while you swap out the springs. And you will also need an overhead valve spring compressor to use to get the old springs out and the new ones in. That is about it for special tools. A fairly full set of hand tools will also come in handy...

You will also want to review the procedure for setting valve lash as you will need to do that to the rockers at the end of the install.

You really don't need to measure anything... Degreeing in the cam would be an optional thing for you to do. It would be a handy thing to do as I don't think anyone has ever really gotten a definitive answer on what kind of figures the LT4 HC will yield... But I (and most of the guys running LT4 HCs) have just installed the cam straight up and had good results.

The springs that come with the LT4 HC kit are good enough to run the .525" lift of that cam with the 1.6:1 rockers, but you will want to verify that the spring retainers will not contact the valve guide tower with the valve seal installed. You may have to have the valve guide towers trimmed down....

Another thing to note was stated above by jamesbern, and that is that the cam is designed to work with a high rpm power band engine, ie. a TPI with stock heads will surely limit the abilities of this cam to make the high end power that it wants to. It will surely make more power than a stock cam in that engine, but it's potential is not going to be fully realized with a TPI and stock heads.

Well, hope that helps a bit... if I forgot anything I'm sure someone will jump in and fill it in.

Good Luck,
Matt

 

It is a bit distorted form the crappy integrated mic on my laptop being too close to the pipes.... But that is pretty much what she sounds like at idle all warmed up.... Compression ratio has a lot to do with how the engine will sound too.... Mine is a hair under 10:1 ....

 

It is definitely a noticable idle depending on how low you set the idle speed, if you set it around 700-800 like myself and Matt it is mean, if you set around 1000 it sounds stock. Is one of the most streetable performance cams I've ever used, about like a 268H with a little more pop. My car is daily driven everwhere and you wouldn't know it wasn't stock driving down the road unless I punched it, but the idle is a dead giveaway.

 

Matt. does every one installing this cam have to trim down the towers you are talking about. I dont want to pay someone to put this cam in. I have put my own motor in and tranny and rear and everything else to my car and cant see having someone else do my cam. I am going to wait to install it until the motor is broken in with about 2K miles on it. Plus I wantto get a baseline power rating with the stcok cam in it. Is there any step by step instuctions out there on how to install a cam. Since it is a post 87 block with a hydrulic roller cam in it, doesnt that mean that the valve lash is set to 0?

 

Yup, all hydraulic lifters should be set at 1/2 turn past zero lash to center the plunger in the lifter bore - flat tappet hydraulic and roller hydraulic.

I really don't know what others have done when they installed this cam. I think most guys that run this cam have aftermarket heads, as well, that will allow that amount of lift or more... I do know one guy running the LT4 HC with 1.5:1 rockers and he didn't change anything but the valve springs.

I don't *think* that you will have to cut the guide towers down on stock heads with only .525" lift, but all you really need to do is measure the distance from the top of the guide tower (with seal installed) to the bottom of the ratainer. You can check this by just popping off a valve cover, pumping up a cylinder with air, removing one of the valve springs and just holding the retainer in place with the keepers in their groove (visually check to see that both towers are the same height as well - they prolly are the same height). That way you will know before you start ripping and tearing..... If that distance is less than .525" , you will need to have them cut down. You will definately need to get the better springs in there, but I am not really sure about the retainer to guide tower clearance.... There has got to be somebody around here that knows the answer to this (five7kid, Engineboy????). I am not really a machinist so I haven't made it my business to just keep that kind of thing stored in my head..... Besides, it is always better to double check as there can be differences in castings here and there.

So once you get that figured out, the only thing needed is pushing in the dowel pin on the front of the cam as the L98 doesn't need it to be as long since it doesn't have that front mounted Optical distributor.

I suggest getting a nice Service Manual (GM one, Chilton.... I don't like the Haynes as much myself - they seem to be made more for smaller jobs and have a lot of really fine print in them..) to have as a reference on this procedure. Pretty much all Service Manuals will give a step by step on a cam swap. I use one on almost all the work I do just to make sure on things and I have done countless cams and internal engine work. It is just nice to give it a quick look and be absolutely certain that you are doing it 100% correct.

Hope that helps,
Matt