results of adding a better cam to a ZZ3 350 sbc

[grumpyvette]

(cam install feed back)

[CARLOS] story:hey grumpy...
I just got my chevy ZZ3 rebuilt.The engine shop did some porting work to the ZZ3 heads and added domed TRW pistons (CR11:1) overbore .030. We left the stock ZZ3 cam in place.
Two weeks ago I went to the dyno where we experienced a clear detonation starting 4000rpm . We had to retard ignition down to 4� idle and 23� max advance above 3500rpm to get rid of knocking. ( 98 octane fuel used already ) This did not really give the hp I expected Engine lost lots of low end response / torque.
Now I read a lot about adding a hotter cam ( later ABDC seems to be the issue ) to bleed off pressure could solve my problem. ( cranking pressure was 175psi before, now it is 215psi )
Can somebody give me a recommendation how to move forward ?My goal is rather to get low end torque than high rpm power.

My combo:
Chevy ZZ3
portet heads
.30 overboreTRW pistons L2304F30 ( should give CR 11:1 accd to engine shop )
Ignition is MDS 6AL with electronical pickup, no vacuum.
Fuel is 98 Octane,
Cam ZZ3 stock
Heddman hot rod headers 1,5" primaries leading in 2" collector, opening to 2,5" tubes and Edelbrock RPM mufflers
Car is Cobra replica
TH350 manual shift kit
holeshot 2000 converter
3,07 rear end

I got a recommendation from grumpyvette for a crower cam, ( remember something like 00471 )

http://www.crower.com/misc/cam_spec/cam ... &x=59&y=12

heres the results

[/quote]
heres a good example of what a fairly well matched cam swap, with 11:1 compression, can do for the power curve, in this case a restrictive exhaust still limits power but yet its still a noticeable improvement

yoooooohaaaaaa !
I installed my engine today, got the CROWER 00471 cam installed with 6� retard. After adjusting my Webbers

WHILE THESE PICTURES ARE NOT HIS CAR THE WEBERS and car WOULD BE SIMILAR

the idle is quite smooth, idling at 600-700 RPMs. Engine feels like it would be a new one, runs extremely soft when cruising.
But boy... if you hit the pedal the Webbers start screaming like hell.
I'll be at the dyno for final adjustment in 10 days. Will post results.


Ok folks, two days ago it was dyno time....

here you can see torque and hp of three stages of modification. peak dates first, tables & images follow later
the curve of the crower is FANTASTIC !!!

1. ZZ3 stock engine, no mods except my Webber 48 IDF carbs
2. same as 1, but heads ported plus TRW pistons added CR 11:1
3. same as two, but CROWER CAM 471 LM added, plus block hugger headers 1 1/2 replaced by 1 5/8 and tubing from collector to H-pipe increased from 2" to 2 1/2"

comments appreciated


1. 316 lbs ft @ 1.500 RPM, 319 hp @ 4.875 RPM
2. 425 lbs ft @ 1.875 RPM, 338 hp @ 5.500 RPM
3. 532 lbs ft @ 2.375 RPM, 361 hp @ 5.500 RPM

I do not care if the values itself are 100% correct, but having the same car on the same dyno, corrected by air temp & pressure should give correct relation.

my snake goes like...well, torque is fantastic, (in combination with a 3000 RPM stall converter that GRUMPY said needed to be matched to the cam) and TH350 manual shifter kit... my cobra at 2.400 pounds ---->>>>is butt kickin' boys !

Grumpy ! Thanks again for the fantastic recommendation on the CROWER

 

[grumpyvette]

now for the fun part, of the story, he had the cam installed ADVANCED 6 DEGREES,, not retarded 2 degrees from the dot-to-dot index location, (which would be retarded 6 degrees from the dot-to-dot index location, as instructed, once he got that cleared up and had better headers installed with a low restriction exhaust added he picked up significantly MORE horsepower, and once he measure the exhaust back pressure on the old exhaust and the new exhaust systems it was all too obvious that the older system was extremely restrictive

 

[grumpyvette]

3rdgenmaro posted this info

the main reason Im posting this is to point out that a fairly simple cam upgrade can easily produce gains of 35-40 hp, over the average stock OEM cam, the G.M. hot cam is DESIGNED to be about pushing too the limit on what can be used with stock components and still function, and yes it really requires upgraded valve train components and its best used with a manual transmission or a 2600 rpm stall converter and a 3.54:1-3.73:1 rear gear.
stock valve springs limit you to about .480 lift the hot cam lift is .525 so the springs ,retainers and rockers are required upgrades

http://www.summitracing.com/parts/NAL-1 ... /?rtype=10
GM Performance 12480002 - Chevrolet Performance LT4 Hot Cam Hydraulic Roller Cam Kits

"5.7 Vortec LT4 Hotcam Install Pics and Information
Well guys, I recently installed a LT4 Hotcam into a 97 vortec motor with a ton of help from Melonhead. I figured I would post up on some part numbers and such that I ran into during the swap. I searched many different forums for help on this, so this thread is meant to be a help to anyone that decides to do the install.

First off, the motor is a carburated 97 Vortec 350 from a truck. It is in my 88 camaro with a stock 700r4. From what I have read, these motors come stock with 255hp. Or atleast that is what GM claims. The motor ran great, had decent power, but I wanted more. I wasnt looking for all out horsepower, but a good streetable cam that would work well with the rest of the engine and that would wake that motor up. I decided to go with the GM LT4 Hotcam. The cam is very streetable, has a smooth idle, and a good powerband that doesnt go too high in the rpm range. The cam is listed as NAL-24502586 (summit number) http://store.summitracing.com/partde...6&autoview=sku
It is a hydraulic roller with 1,500 - 5,800 operating range, 218/228 at .050, .492 lift with 1.5 rockers and a 112 lsa.

The main problem with the vortec heads as many people know is the lift restriction of .480 If you have the heads off the engine, I would recommend having the correct machining of the valve guide done and have screw in studs installed. However, you can make these heads work with larger lift cams without removing the heads. This is where Melonhead was a lifesaver for me. If you use the GM LS6 beehive valve springs (GM PART # 12499224), Comp Cams retainers 787-16, and change the umbrella valve seals to Sealed Power Part # ST2015, you should be able to get up to 0.550 lift. (I am currently only running .492 lift with this combination with no problems, however in the next couple months I will be swapping to 1.6 full roller rockers giving me a lift of .525.)

Swapping the valve springs is simple. Im not going into the details on how to swap valve springs on an assembled engine, you can find that elsewhere. I will say that the new seals go on fairly easily and if you put some oil on the inside it will help it slip on. Using an old retainer from a spring you just removed, press down on the seal until it fully seats on the bottom. you dont need to buy one of those installer tools for $30. The ls6 valvesprings are alittle tight to install sometimes. I had to put some of them under a hairdryer for a little bit for them to slip on. It was tight, but not tight enough to warrant a concern.

One of the huge downfalls of doing this swap with the engine in the car is the stock plastic timing cover. I first started by removing several of the front oil pan bolts. Most of you have pulled a timing cover in car before, so not much detail in that respect. The stock oil pan gasket is a one piece rubber style so be careful. While I was working the cover off, the bottom corner broke. Cheapest place I found was summit for replacement NAL-12562818 $23. The summit piece is built by GM and comes with gaskets and bolts. The crank position sensor holes are in the cover, but if you are using one, you must cut it out yourself.

The crank position sensor trigger wheel is pressed onto the crank in front of the crank sprocket. A screwdriver was all that was needed to pop it off. Gently pry on one side then the other until it comes off the keyway. The rest of the cam change is straight forward, pull spider, pull lifters, pull cam, reinstall cam, reinstall lifters, reinstall spider, reinstall timing gears. For reference the timing set I used was Cloyes CLO-9-1157. Also from summit.

If you take your time, you can reinstall the timing cover with the engine in the car, without dropping the oil pan. It just takes time, patience, and a steady hand. Do not get too forcefull or you will break it. From here on out it is basic reinstall. I set the hydraulic lifters at 1/2 turn.

Distributor gear. That is the big question I had. Do you have to run a bronze gear? No. Since these motors come originally with a roller cam, the stock gear will work with this cam. GM cams use a melonized distributor gear on the cam. However, if you go to an aftermarket cam, you might have to change out since they are billet. But for the GM hotcam, your old distributor gear will work.

I am running an Edelbrock Performer RPM intake with a holley 600 with vac secondaries. I have alot to do under the hood when money allows. Full roller 1.6 rockers, custom wires, custom air intake, and a basic cleanup of stuff under the hood.

The idle didn't change much. It almost sounds exactly as it always had. After some linkage issues I had, I could tell a huge difference in the motor. That cam really woke it up. I have realized now I need to change out the governor in the transmission to let first gear turn higher before shifting. I haven't been able to do any tuning to it lately. The first couple of hard runs has given me a nice little noise somewhere in the drives haft or rear end. Got to fix that first. I am running a stock converter. The only issue I have with it is that at times when you are coasting around a turn or down the road, you can feel the car want to "buck" a little.

http://www.grandsportregistry.com/dyno.htm This is the registry for the 96 LT4 cars and the mods done with dynos done. Most show at least 300hp at the wheels. I have not been able to dyno, but I can say it is a lot more than the 255 the motor started out with.

All together I am completely happy with the swap. I have around $600 in the swap and it is definitely worth it.

I will post up more as I get the time to tune. Here are a few pics.

BE aware you need to verify rocker adjustment lock nut to rocker slot clearance and yes it varies even with the same manufacturers different rocker designs

 

[grumpyvette]

http://www.airflowresearch.com/articles ... /A7-P1.htm

http://www.airflowresearch.com/articles ... 5/A-P1.htm

http://www.airflowresearch.com/articles ... 5/A-P1.htm

http://www.airflowresearch.com/articles ... 9/A-P1.htm

http://www.airflowresearch.com/articles ... 8/A-P1.htm

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YOU MIGHT FIND THESE LINKS WORTH READING ALSO

http://www.hotrod.com/features/1411-wha ... -camshaft/

http://www.bootleggercams.com/#cam-specs

lt4 hotcam comes here inexpensively in a kit with springs and rockers , and whats not being stated, in that bit of LUNATI ADVERTIZING,posted above is the fact,
that you can install the hot cam in the stock engine with just the valve spring and added 1.6:1 ratio rockers and expect it to run fairly well with the stock TPI or LT1 fuel injection system without changing the computer controls injectors , the cars torque converter speed or rear gear ratio, and thats NOT likely to be the case with the more radical and longer duration and higher lift LUNATI CAMS, thus the result you see is a rather apples to oranges comparison, and ID also point out that if your willing to change the heads,rear gear ratio, compression, converter stall speed ETC. theres dozens of cams made by CRANE, CROWER LUNATI,ISKY ERSON
that will provide similar or better results.. provided the compression ratio, converter stall speed and drive train gear ratios match the application of course.

http://www.jegs.com/i/GM+Performance/80 ... 7Aod6RUAsw

THE G.M. HOT CAM has 218/228 duration at .050 lift, and maximum lift with 1.6 rocker ratio (intake/exhaust) is 525/525. Valve lash is zero/zero and lobe centerline is 112 degrees. it was designed to be about the max compatible upgrade that would not require rather extensive supporting upgrades to allow it to function.
(CRANE CAMS USED TO SUPPLY MANY G.M.PERFORMANCE CAMS,
Chevrolet Performance LT4 Hot Cam Hydraulic Roller Camshafts 24502586

this is no longer true and QUALITY has dropped off noticeably by who ever is currently supplying the cams)