ptroxx

OK so I have the ZZ4 installed in my 77 but sure wish i would have just went with the hot cam when we did the swap....

my question is.. what else do i need to do the swap.. i read all i need is the cam and lifters.. i found the cam for 100 new and was thinking i could just get the lifters and save a little..

only have 5 k on new motor..

thoughts..

jabrun

Others might disagree but since it's a roller cam engine I would just reuse the lifters you have with the hot cam. Especially with the low miles.

ptroxx

well I found a new cam being sold new for 100.00 and i have read this...

Technical Notes: the ZZ4 comes with most of the LT4 HOT Cam Kit components already installed. The camshaft and lifters are all that are needed to complete the LT4 Hot Cam conversion on the ZZ4.

Jason Staley

I bought my LT4 Hot Cam off a friend that decided to go even larger in his engine. I just reused my original lifters since they were rollers and don't have the same "wear in" issue as flat tappets. Been in the car for over 8 yrs now with not issues.

The cam does require new rockers though - 1.6 ratio.

ptroxx

Sounds like a mixed bag of info.. some people say all you need is the lifters, then others say all you need is the rockers.. ? ?
THis is a new zz4 with under 6kmiles ..I just wish i would have dont this while the motor was out of the car.,.

daanbc

The ZZ4 is not enough HP? I was planning an upgrade like this for my 77 in the future. Why are you disappointed? Does the LT Hot cam make that much of a difference? What kind of #'s in price and HP.?

crf311

Roller lifters can be reused. hydro flat tappet and solid tappet no way to reuse. IMHO

ikwhite

Correct

ikwhite

ptroxx

right now its getting about 260 rw hp ... yet it is a nice gain, i would like just a little more in the C3.. I think the cam will do it for me.. with the elec fan install i do down the line,

Im just trying to find out if I Have to get the entire cam package , or if i can just get the cam cause from what im reading and being told. even with getting the 1.6 rockers, they wont help that much cause the cam doesnt have enough lift to get the gain from them..

Anyone else ? ?

thatcorvetteguy

I don't know what the ZZ4 hot cam is but if your talking about the LT4 kit they come with rollers. I put the kit in my 385 Fast Burn. The Chevy dealer says it will boost the HP from 385 HP to 435 HP.

Jason Staley

My ZZ4 with the LT4 Hot Cam, roller rockers, lightly ported heads, & Manley valves (improved flow, but stock sized) is making 328 rwhp & 355 ft-lbs of torque on a chassis dyne. So compared to the 260 hp number there is a rough comparison for you (excludes differences in dyne's, trans, etc.). I don't have a direct comparison for just the cam swap.

I'm running in the 12's with this combo and the car is not even set up for drag racing. It's more tailored to road courses and highway cruisin.

ptroxx

I would be very happy with those hp #ers.. thats right about where i wanna be ... and in the 12's is more that good for me in this car. I do a lot of cruising in this thing and i might hit the track twice a yearI plan on going to a 200r with a stall.. and like 3.55 gears.. should be a nice cruiser.. Just need to know what to get.. right now it looks like the cam and rocker arms.. maybe new pushrods. ...

Anyone else with some thoughts on the cam swap../

Jason Staley

Another modification I did a few years ago was recurving the distributer. This really helped the throttle response and general feel of the engine. I installed lighter springs and an adjustable vacuum advance from Accel (I think).

I did this after I went to the dyne, so I can't give you any HP numbers, but the modification was well worth it especially for the street. The engine just feels a lot more responsive to throttle inputs even if max HP numbers didn't change much.

ptroxx

Have had the dist curved and QJ re jetted.. Think it still needs a little adj.. but in time i will get this thing dialed in..
Just need to know what parts to get for the swap.. so far everone says the cam is really all i need, some people say cam and rockers. and others say cam and springs....
Ill get this figured out.... LOL


QUOTE=Jason Staley;1576170622]Another modification I did a few years ago was recurving the distributer. This really helped the throttle response and general feel of the engine. I installed lighter springs and an adjustable vacuum advance from Accel (I think).

I did this after I went to the dyne, so I can't give you any HP numbers, but the modification was well worth it especially for the street. The engine just feels a lot more responsive to throttle inputs even if max HP numbers didn't change much.[/QUOTE]

68/70Vette

In retrospect I wish I'd bought the ZZ386 for my 68. I did buy the ZZ4 hot cam engine however.

At the time I was just wanting a slam-bam-thank-you-mam engine to put in the car to get it on the road. If I had it to do again, I'd at least take the GMPP engine and have a rebuilder do it with an all aluminum block and internally balanced 386.

I suspect that a performance problem with my ZZ4 hot cam is that I'm using the factory sidepipe exhaust system. It's noisy, but I hear that it really nevertheless has a lot of horsepower robbing backpressure. Maybe I'll take the car for a dyno test.

ptroxx

found this thought it was interesting

The LT4 HOT cam is spec'd with 1.6 ratio rockers as follows:
Lift (In/Exh) Duration (In/Exh)
.525 / .525 218 / 228

Versus the standard ZZ4 cam: (w/1.5 ratio)
.474 / .510 208 / 221



w/ Carburetor (*) Production ZZ4 w/ HOT Cam and 1.6 RR

RPM HP Torque HP Torque

2000 125 328 128 336
2500 174 365 174 365
3000 229 400 234 410
3500 271 406 278 417
4000 309 405 318 417
4500 337 393 354 413
5000 354 372 380 399
5500 355 339 394 376
6000 338 296 391 324

jackson

5K on ZZ4 ... suggest stick that $100 lt4 cam in there with NO new rockers ... and put a new chain only in it with NO new sprockets.

If/When you want more "bolt-on" hp ... look at other heads ... perhaps check w/ CF member topgunn as he upgraded his ZZ4 w/ heads & cam.

keep in mind ... those zz4 heads have small 58cc chambers & that's where much of its compression comes from.

fy1 ... OE zz4 spring ( 12551483 ) is very same spring in hot cam KIT.

ptroxx

I plan on putting on an airgap manifold too.. a friend just happens to have one., and as long as it works.. im gonna use it i think..
But your saying cam only huh......
Glad I asked this question.. im getting so much info out of this .. thanks everyone..

ZZ71S

If you do not use the 1.6 self aligning roller rockers you will not get the full .525 lift.
The zz4 with the Lt4 hot cam in the dyno comparison that you posted is using the 1.6 rockers.

Jason Staley

If you use 1.5 rockers, you'll have less lift on the exhaust than you currently do with the ZZ4 cam.