95TALT1

I tried to find the answers myself but was not having any luck. I know there are better cams out there then the lt4 hot cam. I dont have a lot of money to spend but I am wanting a little bit of an up grade on the cheap. Im having trouble finding some specs on valve spring sizes. Can I run a lt4 hot cam with stock lt1 springs? If not will lt4 springs work on stock lt1 heads with out machining the heads? If it works on stock lt1 springs with 1.5 I may run it that way for a while. Maybe upgrade the spring/rockers later. Thanks in advance for any help.

Mswezey

From what i've read the stock springs suck basically.

you'll want at least Lt4 springs for a hotcam if not better (future purposes perhaps?)

no head work should be required and it's quite simple to change springs out.

I'm running beehive 918's, about $197 and hopefully if everything goes right ill be getting 1.6 rockers. BTW I have a cam that is spec'd out to be similar if not the same as a lt4 hot cam. But stock springs would be a no no...some say they have done ok, but a lot others say they end up with coil bind

95mysticta

To be honest by the time you have all the rest of the parts that go with a cam swap your better off spending the extra cash and getting a better cam/springs. I have the Hotcam in my dads 95 and works very well for what he does with the car. But like i said when the parts list adds up and you try and get as much bang for the buck its smarter to save an extra couple hundred on a better cam/springs. Not trying to tell you that the hotcam is a bad cam as its a good street cam but you can use something like a comp cam 503 which will net you easily 10-20rwhp for a little bit bigger of a cam.

Just a suggestion, good luck! Guarantee it will put a serious grin on your face when your get it put together and first start it.

sbs

Really?

http://tinyurl.com/2uva4x5

Z28SORR

http://paceperformance.com/index.asp...D&ProdID=22705

Better off buying the KIT, you'll save in the long run.

pgerst

The LT4/1.6RR yields about .3 more inch lift at the intake valve and about .2 at the exhaust. LT1/1.5RR lift at valve is .447 for intake and .459 for the exhaust; I have read rumors that GM said it was OK to use just the lt4 cam in an otherwise stock LT1. My quick math: The LT4 valve lift spec I have is .476/.479 I/E, as the 1.5 versus 1.6RR works out to 7% less lift, that puts the LT4/1.5RR valve lift at about .46 inch. So you would need the ability to compress the LT1 springs at least an additional .013; i do not know if this can occur without bind or not. You could take off a valve cover and measure the closed clearances on I/E valve springs to determine this.

Some of the more experienced engine guys will correct me but I believe that a good portion of the horsepower gains from the LT4/1.6 come from the extra rpm the lt4 can make (engines were rated at 6300 and 5700 respectively), which, for purposes of this topic, becomes a function of valve spring rates (besides cam/RR, there are also differences in the lt1/lt4 cylinder head which added hp as well.) The LT1 springs have less closing strength and will start to float at the higher rpms (frankly, I suspect they already do at the 5700 redline.)

The peak torque ratings are the same (340, although 500 rpm lower at 4000 on LT1.) Without the ability to turn extra rpm (and w/o lt4 heads), i think you may get more bang for your buck going the other way, lt1 cam with 1.6RR/springs? Also I think there are aftermarket cams that are designed for the LT1 heads that may be cheaper/better?

RamAir95TA

The HP/TQ ratings you are posting apply to the factory LT4 cam, not the LT4 HOT cam. There is a very big difference, so unfortunately your analysis doesn't apply to the OP. Additionally, all the math has already been done. You simply cannot use any cam other than stock with factory valve springs.

If the OP wants a cam swap on the cheap side of things, it is hard to beat the hotcam kit. Everything is included and, while it is dated, still provides decent bang for your buck. Undoubtedly there are better grinds available, but with the hotcam kit there are no questions asked as far as parts selection is concerned. Add a timing set, gaskets, and a tune and you're ready to roll.

pgerst

Good point on the two lt4 cams; which means the required clearance works out even worse on the hot cam.

GRIDERMAN87

YES you can run your stock springs w the cam i do w 1.5 rockers too

RamAir95TA

You are running the LT4 hotcam on stock springs? Man are you tempting fate.

GRIDERMAN87

drive it everyday with 1.5 rockers it lowers lift enough for the stock springs to hold, it wont work with 1.6s

pgerst

Griderman87 -- do you know how much clearance you have on the springs when open?

RamAir95TA

The stock cam has a net lift of .447/.459 with stock 1.5 rockers. The LT4 hotcam has a net lift of .492/.492 with stock 1.5 rockers. Stock springs start to bind at .480" lift. They aren't binding to the point where you're going to experience catastrophic failure because your lifter plungers are what's taking the beating. But don't expect it to last much longer.

pgerst

That is amazing that it is working. Though this is what I love about the orphan LT1, it's the modern day flat head and we are true hot rodders, making our own performance.

GRIDERMAN87

there rated to hold .500