ZZ4 LT4 hotcam install?? [Archive] - Chevy Nova Forum

: ZZ4 LT4 hotcam install??


slickman
30th-June-2008, 02:58 PM
Anyone ever do this swap?

slickman
1st-July-2008, 06:31 AM
I guess no one has done an LT4 hotcam swap so, I'll be the first I guess:rolleyes:

ALLT4
1st-July-2008, 07:34 AM
The LT4 Hot Cam will put your springs at the limit. Luckily they are LT4 springs from looking through the GM Performance Parts catalog. You'll also need 1.6 rockers with that cam. The stock rockers on a ZZ4 are stamped steel 1.5 ratio.

It will work but it's not that much more than the stock ZZ4 cam. The ZZ4 cam is .474/.510 the Hot cam is .525/.525 but you need to change the rockers to 1.6 to get that lift. Also you'll probably need a push rods that are .100 longer. From experience that's the way it usually works out when going to 1.6 from 1.5 rockers. But you need to check length yourself to get the roller tip centered. Is it worth it for .051 on the intake and .015 on the exhaust?

slickman
1st-July-2008, 07:41 AM
Thanks for the input, according to GM the only thing that was needed for a LT4 hotcam swap was the 1.6 roller rockers (which I have) and the cam (have that too). Everything else on a new ZZ4 (which mine is) is already setup for that cam. So, I'm :confused: about you stating I need longer push rods.??

This setup is an option for the ZZ4 right from GMP, I just did not think about it till after it was installed. I spoke to the GMP tech to confirm it and I had everything I needed.

Just looking for anyone who had done this swap already to see if there was anything I missed or should expect to come across. With that said, I don't understand the push rod needing to be .100 longer....:confused:

ALLT4
1st-July-2008, 08:07 AM
You don't really NEED longer push rods but like I said from experience the tip on the roller rocker probably won't be exactly centered. When you change from 1.5 rockers to 1.6 it changes the geometry a little and the tip winds up a bit off.

The only other concern I'd have without looking are there guide plates on those heads or are those stock rockers self aligning? If they're self aligning you'll need self aligning 1.6 rockers. If not you'll need guide plates.

I installed a Hot Cam in my LT4 Corvette, good proven cam no doubt, but in that motor all that was needed was the cam because everything else was already set up for it from the factory. I did change the springs feeling they were a little too close to coil bind. I bought these springs below and they dropped right in. Also provided room for up .600 lift. I couldn't use the ones with a damper though I would have liked to. The damper wouldn't fit over the seal boss but the spring itself fit nice and tight to it. The stock LT4 springs have no damper so that really wasn't an issue. The 99846-16 comes with dampers while the 99845-16 doesn't. Same springs just with or without dampers.

With those springs 7000 RPM is no problem if your motor can handle it.

http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=99845-16&lvl=3&prt=122

slickman
1st-July-2008, 01:17 PM
There are no guide plates, everything is setup to be self aligning. I purchased the roller rockers that are self aligning as well. My concern is that with just the LT4 hot cam and the 1.6 roller rockers, everything should work fine correct? I'm not building a track car, just a real nice muscle driver. I have looked at many tech articles and they all lead me to believe (Along with GMP as well) that with a ZZ4 you only need to add the 1.6 rockers and the LT4 hot cam. Its not that I'm questioning anything and everything, I just want to be totally sure prior to doing this upgrade that it will work the way GM says it will (so I'm told).

If someone did this swap just like I am and had no issues that can tell me, I would be happy with that and have a warm fuzzy..

Here is Gilbert Chevy that basically says the same thing with their upgrade options on the ZZ4. http://gilbertautoparts.com/ChevySmallBlockV8s/PUZZ4.cfm

tom95642
1st-July-2008, 01:41 PM
Add fast burn heads and you have a ZZ430 with that cam and 1.6 rockers.

mikeorwan
1st-July-2008, 09:02 PM
This will most likely be the first major upgrade I make to my zz4 fastburn.
Slickman just compare the Hot Cam Kit part numbers to the part numbers for your head assembly. If springs, etc all match you are good to go with just cam and rockers.

But I agree with Tom95642 add the fastburn heads in your upgrade plans. Bought my 385 fastburn just to get them right off. With the hot cam you're at 425-430 horse.
If I recall right the hot cam doesn't really add that much to the regular zz4 does it?

slickman
1st-July-2008, 09:15 PM
I saw one post on the web of some dyno numbers on a ZZ4 were the LT4 hot cam, full roller rockers and a Edlebrock air gap added 40hp.. Matter of fact if you look at Gilbert Chevrolet web site they give you some numbers based on their dyno sheets that state just that. So, I guess it all depends on your setup and the engine itself.

This will most likely be the first major upgrade I make to my zz4 fastburn.
Slickman just compare the Hot Cam Kit part numbers to the part numbers for your head assembly. If springs, etc all match you are good to go with just cam and rockers.

But I agree with Tom95642 add the fastburn heads in your upgrade plans. Bought my 385 fastburn just to get them right off. With the hot cam you're at 425-430 horse.
If I recall right the hot cam doesn't really add that much to the regular zz4 does it?

slickman
1st-July-2008, 10:29 PM
I just heard from Gilbert Chevy and they said the ZZ4 heads have springs that can handle a .540 lift so the LT4 cam is not a problem with the 1.6 rockers. So, GM tech support and Gilbert Chevy (who do allot of performance builds with ZZ4's) say basically the same thing. So, I'm good to go.

ALLT4
1st-July-2008, 10:37 PM
I just went through the GMPP catalog again, the ZZ4 and Fast burn heads share the same LT4 springs and retainers. If the springs are at installed height the Hot Cam should be a drop in affair with self aligning rockers. Barring seal to retainer interference, you need to check these things yourself. No I haven't done it myself on a ZZ4 but I did on my LT4 motor. The only difference being the LT4 motor/heads come stock comes with 1.6 rockers.

Here's the deal with the LT4 springs and why a lot of LT1/LT4 guys change them. The installed height of the springs are supposed to be 1.78 and they're usually close to that. Coil bind is 1.22 so doing the math...

Installed height 1.78-1.22 Coil Bind =.560 Total gross lift capability.

Gross lift .560-.525 Hot cam lift with 1.6 rockers = .035 Safety margin.

Safety margins are supposed be a little larger than that. Crane recommends (http://www.cranecams.com/?show=valveSpringsFAQ) .060 but the Hot Cam swap is done most of the time with the stock LT4 springs at installed height with no ill effects. On rare occasions I've seen bent push rods though and one can only guess that that close safety margin was probably the culprit. Those that have had that problem wind up changing springs to avoid it again. Most likely they over revved the engine.

Now conversely I don't think GM would sell the Hot Cam kit with stock LT4 springs if they thought it wouldn't work. However I questioned the sensibility of using used springs on a new higher lift cam. Different new springs were cheap insurance to get a little more safety margin, a little more open pressure and rate.

Yes you could probably slap the Hot Cam in and be fine. The difference is in not just slapping parts together and hoping for the best or making some checks and knowing things will work. Just because it worked fine for someone else in the same motor doesn't automatically mean things will work the same even on the same motor. It's up to you to make the checks and insure for yourself.

slickman
2nd-July-2008, 06:20 AM
Thanks for all that work and information, I really appreciate it! As to used springs, my engine only has 600 miles on it so, I don't view them as used. Can I assume that crane recommends using .060 as a safety margin due to tolerances and valve float?

I don't think my engine will ever see over 6,000 rpm, so when you say over revving the motor, what RPM range are you thinking?

ALLT4
2nd-July-2008, 07:16 AM
Well FWIW, I've used as low as .010 safety margin and got away with it for many 7000 RPM shifts. Gotta tell you though I did worry about it. So I think .035 should be fine and GM only reinforces that by supplying the LT4 springs with the Hot Cam kit.

Personally I think .060 is being overly safe, if your springs only have 600 miles on them I agree, they should be fine.

That's only Crane's recommended saftey margin also, there's others that feel .040 is enough. Who's right, who's wrong, who knows.

slickman
2nd-July-2008, 07:19 AM
Thanks for all your help!!

Well FWIW, I've used as low as .010 safety margin and got away with it for many 7000 RPM shifts. Gotta tell you though I did worry about it. So I think .035 should be fine and GM only reinforces that by supplying the LT4 springs with the Hot Cam kit.

Personally I think .060 is being overly safe, if your springs only have 600 miles on them I agree, they should be fine.

That's only Crane's recommended saftey margin also, there's others that feel .040 is enough. Who's right, who's wrong, who knows.

jimfulco
4th-July-2008, 05:45 PM
My main concern would be if using the 1.6 rockers would cause you to have to enlarge the pushrod holes in the heads. Some heads require this, but I don't know about the ZZ4 heads.

There's no law that I know of that says you HAVE to use 1.6's with the Hot cam. You'd lose a little power with 1.5's, with max lift dropping to .492", but I'd be hesitant to use 1.6's unless I knew absolutely for sure there'd be no interference.

tnblkc230wz
4th-July-2008, 06:14 PM
The ZZ383 also uses the same springs with a .528 lift cam.

slickman
4th-July-2008, 07:41 PM
The ZZ383 also uses the same springs with a .528 lift cam.

I did not know that.. Good to know, is that with 1.6 rockers?

Mustangsaly
4th-July-2008, 08:41 PM
I have a Plan But I built up a 400 SBC for my sons 74 Camaro 1st. I have a 1 piece rear main seal 350 4 bolt main block and a GM Forged crank #14088532 and some 062 vortec heads and comp 26918-16 Beehive springs and a fresh set of TRW reconditioned 5.7 rods with ARP bolts, and I was going to add a nes GM Hot Cam to and some 1.6 roller rockers, as I have a good set of GM roller lifters and dog bones and retainer tray for the roller set up, for one of these combos

http://ryanscarpage.50megs.com/combos15.html

this one
Displacement: 355 cu. in.
Carburetor: Speed Demon 750 and a 1 1/2 in. spacer
Heads: GM L31 Vortec
Intake: Edelbrock Super Victor single plane
Camshaft: GMPP HOT hydraulic roller, with 0.525/0.525 in. of lift and 218°/228° of duration @ 0.050 in. of lift.
Exhaust: Hooker 1 5/8 in. headers with Flowmaster 2 1/2 mufflers
Pistons: stock
Rods: stock
Crank: GM
Ignition: Stinger electronic with MSD 6
Timing: 32°
Comp. Ratio: 9.75:1

MAX HP: 422 @ 5700
MAX Torque: 418 @ 5000

or this one

Displacement: 355 cu. in.
Carburetor: Speed Demon 750 with mechanical secondaries
Heads: GM L31 Vortec
Intake: GMPP Vortec dual-plane
Camshaft: GMPP HOT hydraulic roller, with 0.525/0.525 in. of lift and 218°/228° of duration @ 0.050 in. of lift.
Exhaust: Hooker 1 5/8 in. headers with Flowmaster 2 1/2 mufflers
Pistons: stock
Rods: stock
Crank: GM
Ignition: Stinger electronic with MSD 6
Timing: 34°
Comp. Ratio: 9.75:1

MAX HP: 412 @ 5600
MAX Torque: 423 @ 4400

ALLT4
4th-July-2008, 11:45 PM
I did not know that.. Good to know, is that with 1.6 rockers?

Nope, the ZZ383 cam is basically the same as the Hot Cam but uses 1.5 rockers to attain almost the same numbers. Same 112 lobe sepration angle too. I lost my place in this thread, didn't the ZZ4 have stamped 1.5 rockers? So the roller 1.6 rockers you have are a very good upgrade anyway.

ZZ383 Cam...
222/230 .509/.528 112 1.5 rockers

Hot Cam...
218/228 .525/.525 112 1.6 rockers

Hey Mike Orwan, come to think of it you'd be better off using the ZZ383 cam because then you can just stab it in and be done. No need for the 1.6 rockers. You should already have 1.5 rollers right?

edit: crap never mind, just looked it up and they're stamped steel. Something to think about nonetheless.

1969NovaSS
5th-July-2008, 12:21 AM
Just a question, but why are you using a cam profiled for Fuel Injection in a carb'd engine? Dont get me wrong, I installed the LT4 Hot cam with LT4 heads on my LT1 Trans am. Would I do it again? No. If you want more lift, why don't you just add 1.6 rockers to the existing cam? LT4 Hot cam is .525 on Intake and Exhaust w/ 1.6 rockers. The ZZ4 cam is .474 Intake and .510 Exhaust w/ 1.5 Rockers. Instead of going through all the work to change the cam I would try the Rockers alone. The lift on the ZZ4 cam would be .506 Intake and Exhaust would be .544 . I am not sure what clearance you have for the Push rods in the heads but as other have stated, the 1.6 Rockers may throw off the geometry of the Rocker/push rod some. Maybe not enough to really hurt anything but some heads when installing the 1.6 rockers require the push rod slot to be opened some. They even make a tool for it to guide the drill into the guide hole. Like I said, I have the LT4 Hot cam in an LT1 and also have the LT4 heads fully Ported and Polished. Motor is pushing about 445 @ the Flywheel. Again this is w/ Fuel Injection. After having the motor slashed Computer Dyno'd and programmed. I asked the Tuner if that was all she had? He stated I should have gotten a different cam. Again this is just my personal experience with the LT4 Hot cam. There is a difference in a Carb'd cam and a Fuel Injection cam. Duration's are different and also the LSA. I installed a ZZ3 crate motor in a 89 Formula with TPI injection. The car ran good but never did it feel like I was really making good power. After a Dyno run I found out it wasn't really running right even with a custom Chip. I called a few Camshaft company's and asked them about it. Well after some long talks. I realized I was loosing alot of power as for the Cam profile. I changed the cam for a fuel Injected set up and the cam was almost identical to what was in the ZZ3 motor from GM except for the LSA and the duration. What a world of difference.

ALLT4
5th-July-2008, 01:44 AM
.544 would leave a margin of .016 with stock LT4 springs used on the ZZ4. That's assuming they're even at installed height and not less. I would lose sleep over that. Now you're back into talking about changing springs which BTW was one of my first suggestions. The OP wants a simple cam change without getting into all that. I don't question peoples wallets, if that's what they want to do, that what they want to do.

The Hot Cam is proven in the ZZ4 motor and is a drop in affair. I agree there are better cams than the not so Hot Cam as some call it. But the OP would have to make some changes to use something even a little bigger.

I'm going to go out on a limb here, USUALLY heads that come with self aligning rockers, such as the ZZ4 heads, have large push rod holes that well accommodate 1.6 rockers. If not a big fat drill bit works with self aligning rockers, you don't need a slot. We keep talking about 1.6 rockers because he already has them and they're also self aligning.

If not the Hot Cam which has been pretty much figured out that it will work what would one suggest for a different better cam that still works with the stock LT4 springs?

What I would do is skip the 1.6 rockers even though I had them. Ebay item, sell them off. Use the money for 1.5 self aligning roller rockers. Use the GM 12370846 used in the ZZ383 with the 1.5 self aligning rollers or even the stock stock stamped steel ones. The GM 846 would be a true stab and play affair at that, nothing needed but the cam, plus it's dual pattern like the stock cam in the ZZ4. More lift on the exhaust side I think would help the ZZ4 heads breathe better than a single pattern cam.

I'm not quite sure how a cam knows it's in a FI or carbed motor. Although you do see a lot of Compu cam this XFI that and so on.

Boy I'm really tired, am I making any sense at all here? :turn:

slickman
5th-July-2008, 08:29 AM
Just so everyone understands. I went with the LT4 hot cam for the following reasons;

I did not want to screw with the heads
The LT4 hot cam is a proven setup by GM
For the money, I'm getting a nice HP upgrade
It has a nice lope that says muscle car

Steves 70SS
7th-July-2008, 07:26 PM
Did you get it in yet? I would like to know what the result was. I have a zz4 with the fast burn heads that I was also thinking about the cam and 1.6.
I called Pace performance and they told me just by adding the lifters I could pickup 15 Hp. They also told me all I needed was the cam and lifteres.
Everything else was good to go!

Steves70SS

slickman
7th-July-2008, 09:24 PM
I'm still toying with when I want to make the swap. Its still under warranty till November.. I may do it anyway but if I do, I must do it by the end of September or wait till like Dec or Jan of next year. See, I'm going in for surgery on my shoulder again at the end of september and that will screw me up for no less then 30 days. If its anything like the last time (had this surgery last August) it will be more like 6 - 8 weeks before I can drive my car or even think about picking anything up more then 10 lbs.

Steves 70SS
10th-July-2008, 08:10 PM
GOOD LUCK! Hopefully it will not be that long.


Steves70ss

slickman
20th-November-2009, 04:28 PM
I know its been a long time but here's an update. I did the upgrade with the 1.6 roller rockers, LT4 hotcam, Edelbrock air gap and Holley 650 (flows 730). I love it and noticed a BIG BIG improvement !!! Took it for a pass at a local event and it ran great all the way to 6500... This winter I'm adding fuel injection so, we should see another big improvement.:D

Would I recommend it and or do it again? You bet!

novawagonman
20th-November-2009, 08:11 PM
Anyone ever do this swap?

YES :yes: Both my motors have the LT4 Hot Cam

novawagonman
20th-November-2009, 08:22 PM
There are no guide plates, everything is setup to be self aligning. I purchased the roller rockers that are self aligning as well. My concern is that with just the LT4 hot cam and the 1.6 roller rockers, everything should work fine correct? I'm not building a track car, just a real nice muscle driver. I have looked at many tech articles and they all lead me to believe (Along with GMP as well) that with a ZZ4 you only need to add the 1.6 rockers and the LT4 hot cam. Its not that I'm questioning anything and everything, I just want to be totally sure prior to doing this upgrade that it will work the way GM says it will (so I'm told).

If someone did this swap just like I am and had no issues that can tell me, I would be happy with that and have a warm fuzzy..

Here is Gilbert Chevy that basically says the same thing with their upgrade options on the ZZ4. http://gilbertautoparts.com/ChevySmallBlockV8s/PUZZ4.cfm

WARNING: before you install that cam make sure that the dowel pin on the face of the cam is tapped in for your engine when GM installed the pin at the factory they keep it out so it can drive some component on the corvette. if interested i have a link to the install process, learn from me I didn't follow thinking GM was right> I had to remove the timing cover after i started the engine. all I heard was a scrapping sound pissed me off:eek:

slickman
20th-November-2009, 08:24 PM
WARNING: before you install that cam make sure that the dowel pin on the face of the cam is tapped in for your engine when GM installed the pin at the factory they keep it out so it can drive some component on the corvette. if interested i have a link to the install process, learn from me I didn't follow thinking GM was right> I had to remove the timing cover after i started the engine. all I heard was a scrapping sound pissed me off:eek:

Yup, I read all about that prior to my install.

novawagonman
20th-November-2009, 08:26 PM
WARNING: before you install that cam make sure that the dowel pin on the face of the cam is tapped in for your engine when GM installed the pin at the factory they keep it out so it can drive some component on the corvette. if interested i have a link to the install process, learn from me I didn't follow thinking GM was right> I had to remove the timing cover after i started the engine. all I heard was a scrapping sound pissed me off:eek:

Wow I just wasted my time typing all this crap:eek:

slickman
20th-November-2009, 08:32 PM
Wow I just wasted my time typing all this crap:eek:

Sorry, if you read my last post as an UPDATE. I stated I did this upgrade already. :turn: