CalvinMD

going the 383 route on my L98...so far have in mind going with a Comp Cams XR276 grind 502lift Int 510exh 276dur int 281exh dur 112lobe centrline....grind number 08-503-8.....

Will this give me the slighty lopey idle I'm looking for?? I have a 69 302 Z-28 that I love the idle sound and want my 383 to be similiar

looking for what you all have in your cars and your thoughts whatever they may be...trying not to upset the knock sensor and have my power brakes and AC able to deal with the strong idle

My car will also be on a 2800 stall speed and long tube headers and large runners on the TPI as well as larger injectors (29lb/hr) and running through 3:73's

Like to hear from everybody..am I on the right track???????????

rodj

Stock heads ?

3.73's and TPI ; figure you are going to run out of breath real fast
Even aftermarket big tube TPI setups don't make power over 5K
lottsa bottom end torque though

CalvinMD

heads are stock L98's but will be treated to a porting and port matching job....I am looking to make tons of torque from 1800 to about 5500

rodj

Check out
http://xtremecarzone.com.au/index.php?showtopic=386

Bear in mind test engine as much better flowing heads than yours and a 288 cam

GREGGPENN

Why not go to YouTube and search for CC503?

http://www.youtube.com/results?searc...cc503+cam&aq=f

GREGGPENN

You'll get it...but no higher than 4800rpms. You'll feel it level out after that.

C4vettrn

I am running it on my 383 LT-1 and it has great steet manners with good lobe at idle. don't worry about knock sensors you should get them resensatized when you have a chip burned. My motor pull hard with a flat power curve.Make sure they grind it for a 383 motor.

CalvinMD

My machinist has talked me into just sticking to a 355 ci rebuild on my L98...I just need to know the max lift the stock style flat top pistons can take safely..probably going to downsize my cam to the XR264HR 488/495 lift...those 268XFI cams look attractive (as does the ZZ4 Hot Cam) but I'm sure the pistons would need to be modified or ordered special for such high lift (around 570) ...whats the max lift before valves start touching stock type Hypereutectic pistons

rodj

Valve to piston clearance is not a problem
Valve gear is a different matter

http://forums.corvetteforum.com/c4-t...113-heads.html

Setup correctly the $40 GMPP ZZ4 /LT4 springs will get you .525 lift on your heads so you could run either the ZZ4 or the Hot cam

rodj

Why?
Only cost difference on a full rebuild is the new crank and some clearancing of the block for 30 extra cubes
Cubes = Hp
Alright you won't see the full potential with L98 heads and TPI but better base for future mods

CalvinMD

thanks guys...here is a pic of the patient..forgive the crappy phone photo

GREGGPENN

Double why?

CalvinMD

I may stick to my guns after mulling over all of this,,....if I do go the 383 route now , which I am leaning towards..then I will go with the XR270HR or the ZZ4 Hot cam...which ever one I can find the best deal on....going to do the whole kit with 1.5 Magnum roller tip rockers ...as long as it runs strong to a bit over 5K after launching from a 2500 stall speed , I'll be tickled pink....I already have the intake base worked with the large runners and BBK 58mm TB..and I'm already running the Dana 44 with 3.73s on a new posi unit taking power from the built 700r4. The wheels and tires are brand new 17's with the correct offset with 315/35's in back. The brakes are all EBC pads with Powerstop slotted and drilled rotors on all new bearing hubs..the heads will be port matched to the intake and headers..the rest of the exhaust is one Magnaflow hi flow cat and no mufflers. Going to also do the swap to the all analog dash from Corvette Central if I have any pennys left after the motor build

GREGGPENN

If you can have them flowed, you'll have a better idea what lift you can throw at them w/o stalling flow. OTOH, if you're only going to install 1.5 rockers, any of the cams you mentioned will "work".

Note: The GM ZZ4 cam and the GM Hotcam are different. IIRC, the ZZ4 is smaller than you'd want on a 383...while the Hotcam is 218/228 .495"/.495" 112LSA with 1.5rr.

Are you thinking of a ZZ9 cam by TPiS? 212/226 .483/.520" 112LSA with 1.5rr?

CalvinMD

My head is hurting...my machinist after I tolf him I still wanted to go the extra cubes now is insisting I use a Lunati Voodoo 270/278...I told him just go for it..as long as it runs..excuse me while I go look for some Tylenol and a beer

rodj

Means little
Advertised duration as you show can have little relevance to actual working duration
We need @50 duration ( like cam specs GP posted above) and valve lift ( w/1.5 rockers ) to comment

CalvinMD

here goes:
CAMSHAFT SPECIFICATIONS: GM LT1-LT4 350 c.i. 1993-1997

HYDRAULIC ROLLER: Strong power increase in mildly modified engines with excellent throttle response. Will work with stock converter in 383-up cubic inch. Likes 2000 RPM converter in 350 or less cubic inch applications. Likes 3.23-3.73 gearing. Has noticeable idle and likes headers.
Hyd
Hyd
1800-5800
60121
NA
270int
278exh
219int @50
227exh@ 50
.515lift int @1.5/1
.530exh lift
112° LSA

grantar2

If your going to have the heads machined consider having the valves unshrouded. Makes a huge difference in flow.

mtwoolford

I dunno; but everytime I've gone with a GM cam, its always worked for me. So whadda bout:

GM Performance 19210723 (replaces 12370846), stock cam in GM ZZ383 cubic inch crate engine (425 horsepower / 490 foot pounds torque).

basic rpm range: 2000 to 6500;
intake duration @ 0.050" lift: 222 degrees
exhaust duration @ 0.050" lift: 230 degrees
intake lift w/1.5 rockers: 0.509" (0.546" w/1.6 rockers)
exhaust lift w/1.5 rockers: 0.528" (0.567" w/1.6 rockers)
$296.95 at Pace Performance; $309.95 at Summit.

Of course the fly in the ointment is whether the valve, valve retainer, valve guide, seal, and spring pack can accomodate any of the valve lifts that are being considered. I could be wrong, but I believe that valve lifts in the range of 0.488 inch are about the max a stock head can accommodate.

Good luck, sounds like you're doing a nice build.

Marv02

Is this a LT1 or a LT4 cam do you have the part Number.