92g92

With new valve springs, will the stock 083 heads be able to handle the lift of the LT4 Hot Cam on 1.5 RR? I have searched and read many informative threads, but it seems that it split 50/50 on yes or no. One thing I did read was something about adding new springs to handle the lift (planning on this) and adding valve spring shims and off set. I do not know how these are used and upon googling it, I still don't have an answer. I did search the parts and they come in various thicknesses, so another question I have is which thickness to use and how many? I know you guys love to say search and I have, just haven't found any threads with this shim/offset combo to be able to safely get more lift on the valves. I read that with new springs and shims and offset, they could safely handle around .525" lift. Any help is greatly appreciated.

Damon

I haven't tried using offset locks + shims personally but I don't see any reason it wouldn't work. In stock form most GM heads of that area have about .460-.470" clearance before the retainer touches the guide seal. So an extra 50 would put you about there.

Another way to do it is get a set of (reasonably cheap) LS6 beehive springs off eBay and a set of Comp Cams beehive retainers for 11/32" valve stems (not LS6 retainers- they're for metric sized valve stems) and gain clearance as well as better valve control that way.

Johnny Blaze

iTrader: (15)

Only way to know for sure is to set the spring up and check for clearnace at max lift.

I see the .470" number and the .525" numbers both thrown around a lot. Similar with GEN 6 BBC lifters, some say .550" others say .600"

Chuck84TA

Perfect timing on the thread!! I was going to ask the same for my build!

Chuck

Johnny Blaze

iTrader: (15)

Why the HOT cam? It used to be the hot cam but these days most guys say there are better choices.

InfernalVortex

iTrader: (4)

Comp pn 787-16

InfernalVortex

iTrader: (4)

There's better choices than 083 heads. Theres better choices than 350's. There's better choices than 3rd gens.

LT4 hotcam makes sense if the price is right and it allows you to run really cheap valve springs with no repercussions. Is it worth the work and smaller monetary investment? It depends on how much your money and time is worth to you, but it's better than any factory thirdgen cam by a pretty large margin. I think it's a fine cam for a hot street car if you're pinching pennies. Certainly a hell of al ot better than any summit brand cam or "RV cam".

Johnny Blaze

iTrader: (15)

Well, if the price is right sure.

92g92

So to my understanding, shimming the new springs up about .050" would get me the clearance needed for the .495" lift of the hot cam? As for your question Blaze, Vortex answered it.

MoJoe

iTrader: (5)

Shimming springs don't "get you clearance". Shimming springs are to get to the recommended "install height" for the springs, which gives you the required seat pressure (spring pressure when valves are closed).

If +0.050" retainers will give you clearance, and IF they also increase the installed spring height (I do not know for sure), then shimming the springs will be required to close the installed height back to the recommended amount.

thunderstick

are you leaving the heads on and just doing a cam swap? not knowing what your time and $ allows, if it were me (and i did it) had the heads machined to accomodate the springs that are available for that cam to run with 1.6 rockers. not sure that you could run stock springs with that cam anyways, but i'm not an expert in that field (or any other field, for that matter ). i just wouldn't try it...

Johnny Blaze

iTrader: (15)

I went with a smaller comp cam, and my 083's were cut for bigger springs. Comp part number 986.

92g92

I will be getting bigger (or stronger, however they are referred) valve springs. I have heard the LT4 springs are not ideal. Any other possibilities for stock heads?

MoJoe

iTrader: (5)

As Johnny suggested, Comp 986 springs. $80 @ Summit. 322#/Inch. From Johnny, it sounds like the 1.430" outer diameter requires machining the spring pocket.

Chevy LT4 are $44 @ Summit. GM PN 12495494. 332#/inch. 1.32" should be direct fit,as they are marketed for stock heads. But interweb lore recommends against >.510" lift of 6000rpm.

If you want to step up (+$) to beehives: Chevy LSx, search for GM #19300952 for a kit. Or start with this for more info. Going back to Comp... 26915 springs @ 313#/inch, with a 1.290" OD. Or the 26915 kit with springs, retainers (necessary to switch to beehives), locks, seats and seals. Going to EBay and AtlanticSpeed will save very little after shipping, but is what showed up in Goolge before looking it up at Summit. Or a Howards kit, without seats or seals.

The Comp 26918 beehive at 372#/inch is a stiffer spring than you need.

jamon8

iTrader: (3)

its 492 lift and you can run that kind of lift with stock heads I am doing it right now with no issues. all you need is valve springs to match the cam. I would tell you what I am running for springs but my machinist ordered them

1gary

Stop-Look-Listen.

To say a cam is a stand alone part is one of the most backward nonsense B.S.ideas going.

Carry on.

92g92

I THINK I might understand what you are stating, but could you elaborate?

MoJoe

iTrader: (5)

You have to think about the entire engine to be a complimentary package. And not just "stab a cam in it".

For instance:
- AFR 210 heads would be waste of money on a 305. The low air velocity would perform poorly too.
- a 300* advertised cam would be a poor choice for an engine that will only rev to 5000rpm. Or on an engine with 8:1 compression.

Johnny Blaze

iTrader: (15)

Are you saying the hot cam is not the hot choice for him?

92g92

Hmmm I don't know about that one. New heads:not gonna happen. Money. Any port work on the heads: not gonna happen. Full exhaust is on the car topped with an HSR. All i want is a cam for a bit more go power, one that will work with the stock heads, albeit with upgraded valve springs. If you guys could offer an opinion as to a better cam for my scenario, I would love to hear it, seriously. I've researched a decent amount and understand that the LT4 hot cam is a great choice for my criteria. If it is otherwise, chime in.

1gary

Of what I just realized is 2,200 posts from me about haft of them are about this very thing.

But you said you did the research.

Somebody

92g92

Hahaha okay I get it. Honestly, I love the supreme members on this forum. I feel like I am in a guild and the supreme members are the wise old teachers with eons of knowledge contained within themselves. I WANT to know their opinions on this matter. Everything I have learned has been through reading, research, and (admittedly limited) experience, basically learning as I go along on projects. No one in my entire family is interested in cars except for me. Please, share and guide me!

jamon8

iTrader: (3)

I make quite a bit of power with the lt4 hotcam and it was cheap. my setup is ported out to the max and some slp runners. if you want I can call my machinist and find out what springs he put in my heads. you don't need any crazy ls beehive springs although they would be nice. ask any of these supreme members if they run a lt4 hotcam and listen to the ones that have

1gary

It is NOT a question of buy and using the best you can get.It IS taking what you have and matching those parts.The days of slamming a cam(any cam where it doesn't matter and it does)turns back the clock to over 10 yrs ago.Be smarter than mob rules.Follow the guidelines of matching up parts and all the benefits from it.

Johnny Blaze

iTrader: (15)

Isn't the purpose of the op's post is to find out what springs he can use with the cam?

cuisinartvette

If he isnt sure how to do it himself best thing to do is take the heads in have them checked and set up properly so theres no doubt. Little labor and some gaskets no big deal.
Hang the valves open longer/farther will net him a gain in power. Its a small cam bet he manages Ok
Some things are better to pay a pro to do just to make sure and not do it twice.

jamon8

iTrader: (3)

here is a youtube of the engine with open headers

1gary

X2

92g92

....okay hold it. I know how to do it myself, I have swapped cams before. The only thing I'm questioning is the max valve lift on the stock heads with up rated springs. As for cam choice, rather than say, "Match your parts." and then go away, could you offer a suggestion as to an appropriate camshaft? I have assumed that a street, daily driven 350 with full exhaust topped by an HSR would find a perfect cam match in the LT4 hotcam. Am I mistaken?

1gary

The chart:

http://www.crankshaftcoalition.com/w..._compatibility

92g92

Awesome chart, thank you, simple way to show the relation. However, according to the chart and article, the LT4 hot cam is SMACK IN THE MIDDLE of compatibility with my set up.

Johnny Blaze

iTrader: (15)

Yep, the hot cam is just fine.

Like I said before, about the only thing that you could really do is mock up a valve with the spring, valve seal and retainer and measure the max lift clearance at the guide.

1gary

57 posted those cams have to use 1.6 rockers.Not trilled with that,but if that is the design of the cam,then you got to go that route.

Johnny Blaze

iTrader: (15)

Why do they "have to use 1.6 rockers"?

92g92

1Gary, not being antagonistic or argumentative, genuine curiosity, what is the reasoning behind 1.6 rr necessity? I agree with you in that 90% of the specs of the cam that I have seen on various sites are given with respect to 1.6 rr. Increases the lift to .525, which I probably wouldn't be willing to risk. Do you know why they might require 1.6 rockers?

1gary

I was somewhat surprised about that myself.Might want to PM the mod 57 for the reason.

InfernalVortex

iTrader: (4)

I think they just have to use 1.6 rockers to get to the advertised specs. I'd use 1.5 rockers on them all day long. I dont like 1.6 rockers. I mean can you think of any reason, Gary, that a cam could "only" use 1.6 rockers? Doesnt really make sense. So I think he was just referring to hitting the numbers the hotcam is referenced with requires 1.6 rockers.

But roughly with 1.5 rockers you're looking at about 218/228, .500/.500. Maybe a tad less duration, but the duration in theory should be very close if not the same.

1gary

PM sent Hopefully 57Kid will chime in.

five7kid

iTrader: (14)

Well, I'll jump in just to clarify what I was quoted as saying:

In another thread, the topic was using 1.6:1 rockers. The cam that the OP of that thread was going to use was spec'd for 1.5:1 rockers, and was pretty mild. In that thread, I said the 1.6:1 rockers wouldn't help that much, and to save them for a cam designed for 1.6:1 rockers, like the LT4 Hot Cam. My point was to buy a cam that worked with the 1.5:1 rockers that guy already had, rather than use a lesser cam and then spend more money on 1.6:1 rockers.

That doesn't mean the LT4 Hot Cam won't work with 1.5:1 rockers in a non-LTx application.

But, if I was putting it into an LT1 and upgrading to roller rockers, I'd probably up it to 1.6:1 rockers while I was at it. You won't get as much power out of the LT4 Hot Cam with 1.5:1 rockers as you will with 1.6:1, obviously.

Hope that clears up the misunderstanding.

RyanJB

I actually have a similar set up. The hot cam does work and it does make good power when set up properly with my vortec heads. I was never satisfied with the power though and have wished I went with the 280 XFI. But that cam might be too extreme for your desires. I'm running heads that are good for .600 lift, but my heads aren't exactly stock.

1gary

Oh.