Installed LT4 Hotcam...

...has anyone else on here used it in their LT1? I just put one in my 94 RMW with 230,000 miles.

This was my first time installing a cam on anything, and like a newb, I just bought the cam not the whole kit. I was reading on some other forums and guys were saying the stock LT1 valve springs and rockers probably won't take the hotcam for too long. Those same people were saying the LT4 springs were just barely enough for the hotcam. I've already started it and let it run for a while and while the springs don't seem to be binding at all, I still feel as though I should get a different set.

Sorry for the long winded post here, my question is...what valve springs and rockers are you guys using with your aftermarket cam and do you like them?

Thanks in advance for any advice.

-Collin

Collin, Here ya go.

A. Valve Springs:

Purpose: Keep the valve in control.
Benefit of Upgrading: Upgrading the valve springs is ABSOLUTELY mandatory in doing a cam swap. The stock valve springs CANNOT handle any more lift or RPM than the stock cam puts out as well as a cam with a more aggressive lobe design.
Required: YES.
Popular Choices: Crane Dual Spring Kit 10308-1 (includes locks, retainers, shims), PAC Beehives 1218 or Comp Cams Beehives 26918. Note: Make sure the valve springs you purchase are matched to the camshaft you plan to run. You do not want the valve springs to go into coil bind which is maximum compression of the spring till its solid because this will cause a major failure in the motor.
Along with valve springs, you will need locks, retainers, shims, and valve stem seals (16). The LT4 valve springs located in the LT4 "Hot Cam" kit should NOT be considered to be run with any cam due to the fact they are known to be very weak and only have a max lift rating of .540 which is not high enough for most off the-shelf camshafts.

I like the beehive springs. You will have to determine the compatibility with the cast heads. They are a drop in for the aluminum heads.

Gotta say here, Collin, that you dodged a bullet by not going into coil-bind. Not too smart.

Would advise against driving and if you must drive it,, DRIVE VERY GENTLY!

Thanks all for the replies, it's just my backup driver so I don't need to drive it, I will let it sit until I have new springs for it.

So just to open myself up and seem like more of a novice, is there anything else inside the motor that I should have replaced?

I did...
Cam
Timing Chain/Gears
All gaskets/seals
Optispark

How about pushrods and lifters? I've heard both ways on those also.

The lifters should be fine for a Hot Cam unless they have over 100k on them or they are noisy, then it would be worth replacing. Look at the LSx lifters, they are supposed to work with our cars, but be sure the push rods do not change (measure your need).

The pushrods would be fine unless you go to non-self aligning roller rockers forcing you to use guide plates and therefore you need hardened pushrods. If you are running the stock rockers that is why you got away with the hot cam and stock springs (note the spec below).

Roller rockers free up some parasitic HP loss from friction. A roller tip or full roller rocker will free up a couple of HP and reduce engine temps slightly. If you chose to go to a 1.6 ration rocker will also increase your lift and the Hot Cam will come into its own (increasing torque). The Hot Cam was designed for use with 1.6 rr's. Make sure you have enough clearance on the pushrods to increase your ratio before you spend $300 on a set of these. My stock Buick heads would not let me use roller rockers, but my Impala SS heads had no issue.

Hot Camshaft (P/N 24502586 Specifications
Intake Exhaust
Lobe Lift 0.328” 0.328”

Valve Lift
@ 1.5 ratio 0.492” 0.492”
@ 1.6 ratio 0.525” 0.525”

Duration
@0.006 cam lift 272° 281°
@0.050 cam lift 210° 228°

Lobe Centerline 109° 115°

Lobe Separation 112°

*********************

This is a link to the springs that I would suggest. Not sure if they are a drop in on the cast heads. Both of my cars I have converted to Aluminum heads.

Everyone's been a novice. No worries there. Live and learn and do it better on your next engine.

Lifters don't need to be changed unless they are worn/scored
Pushrods need to be properly measured. If they are the correct length, no need to change them. Exceptions would be a 1996 car using non-self aligning pushrods. The 96 had unhardened pushrods, so you would need to get hardened pushrods. Your 94 pushrods are hardened.

I do the following when changing a camshaft:
- GM "white" oil pump spring p/n 3848911
- oil pump driveshafts: Melling IS-55E, Arp 134-7901

Remove the 4 bolts holding the bottom plate on the pump housing, then you can punch out the small roll pin that retains the spring. While you're in there don't forget to weld the pick-up tube onto the pump. Also, drill housing to open the outlet port to main bearing cup & deburr the edges.

Doing a cam swap at 230k miles without a complete refresh might be a bit of a crapshoot. Don't be shocked if you spin a bearing.

The GM hot cam .525 / .525 is specced with 1.6 ratio roller rockers. The way I read your post you are still using the stock stamped rocker arms so you are looking at .492 lift. You're cutting it dangerously close, but it's not as catastrophically close as if you had 1.6 rockers.

Upgrade your springs. Tthe correct Crane part number is 10309-1 for iron heads NOT / NOT 10308 as given above. That is for Al heads. The beehives are very nice as well. Get yourself a decent set of 1.6 ratio rockers (Scorpion, Comp pro-magnum, Crane gold and the GMPP LT4 1.6 rockers can usually be found used for a decent price). Self-Aligning (3/8" stud) are the most straightforward to install. I would stay away from aluminium offshore rockers, like the summit brand. When you are doing the springs, it makes no sense not to do the valve stem seals at the same time.

Good luck, but don't be dismayed if you spin a bearing after a few miles.

[edit: looks like Tim beat me to the punch on a few points]

i have comp cams beehive springs with steel heads you will also need new retainers if you go with them

Has anyone done a controlled, before/after HP check with roller rockers?

I read a write up once about 8 years ago about a SBC on the dyno with all different combinations of rockers. The full rollers did the best HP wise and engine temps. Not a huge increase, but less wear on the valve train.

jimbeau wrote:

Has anyone done a controlled, before/after HP check with roller rockers?

yes.

Guys, I just want to say thank you so much for all the help. I have several write ups that I've done over the years on wagon information that I will be posting to add to the community a little bit. I may be a novice at tearing an engine down, but these wagons have been my passion for years. If it weren't for you guys I probably would've been out flogging it already, thanks for informing me enough to make a wiser decision.

-Collin

jasonlachapelle wrote:

I would stay away from aluminium offshore rockers, like the summit brand

What do you guys think of these? Sound a little offshore to me
[You must be registered and logged in to see this link.]

GG91Wagon wrote:

jasonlachapelle wrote:

I would stay away from aluminium offshore rockers, like the summit brand

What do you guys think of these? Sound a little offshore to me
[You must be registered and logged in to see this link.]

One word = JUNK

Comp Cam Pro Magnum or the new Ultra Pro Mag is the way to go.

I am looking to split up a set of New 1.6 Ultra Pro Magnums with the half of the current set of 1.5 Pro Magnums I have on the motor. This will max my power and efficiency with the 1.6 on the intake valve and 1.5 on the exhaust side. If any one is interested in half a set of 1.5s or the other half of my set up, LMK.

Tim

BigBlackBeaSSt wrote:

Comp Cam Pro Magnum or the new Ultra Pro Mag is the way to go.

I am looking to split up a set of New 1.6 Ultra Pro Magnums with the half of the current set of 1.5 Pro Magnums I have on the motor. This will max my power and efficiency with the 1.6 on the intake valve and 1.5 on the exhaust side. If any one is interested in half a set of 1.5s or the other half of my set up, LMK.

Tim

Mebbe work better with better exhaust lift,.

Nick

BigBlackBeaSSt wrote:

I read a write up once about 8 years ago about a SBC on the dyno with all different combinations of rockers. The full rollers did the best HP wise and engine temps. Not a huge increase, but less wear on the valve train.

UPDATE!! Hot Rod Mag just did an article on this again in their September issue.

phantom 309 wrote:

BigBlackBeaSSt wrote:

Comp Cam Pro Magnum or the new Ultra Pro Mag is the way to go.

I am looking to split up a set of New 1.6 Ultra Pro Magnums with the half of the current set of 1.5 Pro Magnums I have on the motor. This will max my power and efficiency with the 1.6 on the intake valve and 1.5 on the exhaust side. If any one is interested in half a set of 1.5s or the other half of my set up, LMK.

Tim

Mebbe work better with better exhaust lift,.

Nick

You may be correct Nick.

jasonlachapelle wrote:

jimbeau wrote:

Has anyone done a controlled, before/after HP check with roller rockers?

yes.

And the results,please?

[You must be registered and logged in to see this link.]. Ed Wright got 4 RWHP on a back-to-back swap.