Pat,

I sent you a PM re: your headers. I would be interested in them if you are still wanting to move them... Of course, I don't get home until August...

 

I just checked specs on their shorter duration cams. The Voodoo 256 shows me good numbers on DD2000. Extracted from Lunati's web site:

BIG BLOCK CHEVROLET

Voodoo 250:
60200 60200LK 250/256 207/213 .495/.515 112/108 71817 73815 75702LUN 77004 65001LUN idle-5000
Very strong torque and increased HP for small cubic inch motors (289 thru 302). Compatible with stock "Speed Density" type fuel injection. Works great for pleasure/ski boats, and mild towing applications.

Voodoo 256
60201 60201LK 256/262 213/219 .515/.530 112/108 71817 73815 75702LUN 77004 65001LUN 1000-5500
Best mild performance cam. Works excellent in Mass Air fuel injection applications. Makes approximately 19" vacuum at idle. Great for performance oriented marine applications and heavy towing applications. Perfect "STREET ROD" cam. Has SLIGHTLY noticeable idle, works with stock converter, A/C, power brakes and STOCK valve springs in MOST cases.

Voodoo 262
60202 60202LK 262/268 219/227 .530/.542 112/108 71817 73815 75702LUN 77004 65001LUN 1400-5800
Mid-level performance street cam with excellent drivability. Works well with stock type exhaust manifolds and dual plane intake with mild 4 bbl carb. This is an AWESOME 4x4 and Performance Marine cam where "DRY" exhaust is used. Improved valve springs and roller rockers are recommended.

Voodoo 268
60203 60203LK 268/276 227/233 .542/.554 110/106 71817 73815 75702LUN 77004 65001LUN 1800-6200
The most awesome "268" cam ever produced! Out-powers all others! This HIGH Performance street cam likes 2400 RPM stall, 800 cfm, dual plane intake and headers. Makes un-equalled power to 6200 RPM with proper valve springs. If you're looking for a VERY STRONG cam with great street manners for your "CRATE MOTOR", this is it! Factory EFI motors need custom chips / tuning.

Note the 213/219 duration of the Voodoo 256. It has lift of .515I/.530E and looks to be the one to beat for street driving without high revs... The power should feel good to 5000 rpm - I have shifted gears by then usually... This cam may be a better pick than the Crower I mentioned recently. Just have to be sure it will handle 9.5:1 CR without detonation - could have to drop back to 9/1 CR...

 

This may only interest a few of us who are starting from a stock motor, but I think I know have enough info to provide good numbers from specs, books, and DD2000. I have not actually measured my cam, but it is likely worn down anyway!

Tom's '73 Vette web pages give the cam data for seat-to-seat timing. Inputting that info in Desktop Dynos 2000 gave me the lobe center (or LSA) of 114.5 degrees, and the intake centerline (or LCA) of 118 degrees. These two values for a cam, once known, remain constant whether you use seat-to-seat or 0.050" values for lift and duration.

I thought I had read somewhere that the duration of this cam was 210/210 at 0.050" lift, so I had been using this data to baseline my motor in DD2000. Well...I just got a copy of Ed Staffel's OTHER big block chevy book, Chevrolet Big Block Parts Interchange Manual, and he lists the 0.050 duration as being 228/228 degrees.

Using my values and the updated values from Ed, I now get power output figures on DD2000 (Max Tq of 398 @ 3000, Max HP of 292 @ 4500) that are very close to Chevy's net power rating claims for the engine.

As such, here is a "cam card" for you:

PN 353040 Chevy BB Cam (in engines to include 1973 Corvette LS-4)

(Cam Specs at 0.050" lift)
Lobe Center 114.5 Valve Overlap -1.0
Intake Lift@Valve 0.440" Intake Duration 228.0
Exhaust Lift@Valve 0.440" Exhaust Duration 228.0

IVO (BTDC) -4.0 IVC (ABDC) 52.0
EVO (BBDC) 45.0 EVC (ATDC) 3.0
ICA (ATDC) 118.0 ECA (BTDC) 111.0

 

From reading the books I mentioned earlier I note that a theory is that you target your CR based on the intake valve closing (fully - not just the 0.050" spec). See pg 113 of Ed Staffel's book on '90's style rat motors. Anyway, Ed (in consultation with Dave Vizard) calls for an intake valve closing spec that leaves 88% of cylinder volume for use with 9.5:1 CR. Using the table at page 108 for a 454, Ed calls for a cam with intake valve closing at 48 degrees for 9.5 CR or one closing at 55 degrees for 10.5 CR. Run seat-to-seat specs on your chosen cam and you will find that these intake valve closing figures will make you choose short duration cams. In fact, by Ed's math, the Voodoo 256 (with 56 degrees IVC seat-to-seat) would work best with 10.5:1 static CR. Is that a ping monster waiting to be built or I am onto something here?

 

Hi,

Firstly Breathit has got his act together. I could not agree more with his statements.

Secondly I like the Voodoo line of cams. They look real good. I don't have DD2000, but would like to see the numbers for the voodoo 256/262/268. With the right LSA and engine I believe could be right for our application.

I say "our" as I believe we will be after the same type of engine. I will be rebuilding my stock LS-5 one of these days. I want a "driver". 400 hp with lots of low and mid range torque. Hence I am thinking, stroke it to 496, which is easy, stick with stock manifolds and an 68 alum, stock intake. So that limits my duration....maybe go with "stock" style alum heads with ~ 8.5 CR. That means my reworked by Lars Q-jet stays as well. And my car looks pretty much stock, but...has torque. Also I have a 3.08 with a M-20, but want a 5 speed, someday...I'll use hypert pistions and coat the pistion tops and vlvs etc for better heat resistance and flow etc.

Also $1400 for a rebuild seems cheap...Funny I enjoy the rebuild, just don't want to take the engine out and install it!

carbster09

 

Carbster09,

If you use aluminum heads you can get up to a full point higher on the CR than with iron heads. As street wisdom says 9.5:1 CR is OK on pump gas, that's why I wonder if 10.5:1 CR using aluminum heads might be OK. You definitely want all the CR you can get - it is free HP and torque, especially down low in the RPM's - but you can't go past the point where you get detonation and can't run on pump gas. The rub - where is that point? Using the Voodoo 256 cam, small-tube headers, and playing around on DD2000 shows me ~22 ft-lbs and ~59 HP more just from bumping the CR from my planned 9.5 to 10.5 and switching to GMPP al heads. Power peak is 402 HP @ 4500 and 518 Ft-lbs at 2500-3000 using GMPP aluminum 110 CC heads (what come stock on the ZZ454 crate engine)and 10.5:1 CR. By comparison, my stock '049 cast iron heads fitted with larger 2.19"I/1.88"E valves and using the same 10.5:1 CR show just a bit less power (392 HP @ 4500 and 517 ft-lbs @ 2500). Running stock heads and valves (2.06"I/1.72"E) at 9.5:1 CR gives 343 HP @ 4000 and 496 ft-lbs @ 2000-2500. If I were to use the Voodoo 256, retain the stock heads and stay with the stock 8.25:1 CR my power really drops: 319 HP @ 4000, 470 ft-lbs @ 2000. If I run my stock cam and engine data, but keep with small-tube headers, I get even less power: 320 HP @ 4500, 427 ft-lbs @ 2500. This spread should show the large possible power gains from the right cam and CR. By the way, if the numbers above don't say it, our stock cast iron heads seem to be begging for bigger valves. I got lots of good head data from reading a nice article here about flow rates on various BB Chevy heads:

http://www.chevyhiperformance.com/te...98/index8.html

My car has the '049 heads, so I put those values in for use in DD2000. I also used the values for the aluminum heads in making comparisons.

 

Here is a link to a great article using 3 of Comp Cam's XE series:

http://www.compcams.com/Community/Ar...?ID=1108284073

I am currently setting up my car to perform as the XE274 cam is being used in this article... You may like the XE268...

Bob

 

Guys,

Still figuring out what to do...

I'll do a compression check and decide if a rebuild is needed yet. I may be able to get away for now with a cam swap. I could also add 100cc Edelbrock Al heads and bump up the CR a bit over 9:1 leaving the bottom end alone. If a rebuild is needed, I found some good deals on Scat kits at Flatlander Racing. Their cast 4.250" stroker crank kits with my 2-bolt block and intended use may be OK.

As for the stock cam specs - again... Quoting myself from above:

I thought I had read somewhere that the duration of this cam was 210°/210° duration at 0.050" lift, so I had been using this data to baseline my motor in DD2000. Well...I just got a copy of Ed Staffel's OTHER big block chevy book, Chevrolet Big Block Parts Interchange Manual, and he lists the duration as being 228°/228° at 0.050" lift.

Well, I dug up an OEM Cam table from their website http://www.flatlanderracing.com/musclecams.html and it shows my stock '040 cam as 210°/213° duration at 0.050" lift. That would make it more of a torque performer than I had decided it was based on seeing the other stat of 228°/228° duration. I see a parallel as Cadillac used a better stock cam in 1973 and Pontiac had its SD-455 that year. GM may have been trying one last time to use cams with better performance - a last hurrah before the muscle cars went away. In any event, a swap to a new design even with similar advertised duration will likely get me more power due to more aggressive ramps and higher lift.

Here is a revised 210°/213° "cam card" for you:

PN 353040 Chevy BB Cam (in engines to include 1973 Corvette LS-4)

(Cam Specs at 0.050" lift)
Lobe Center 114.5 Valve Overlap -17.5
Intake Lift@Valve 0.440" Intake Duration 210.0
Exhaust Lift@Valve 0.440" Exhaust Duration 213.0

IVO (BTDC) -13.0 IVC (ABDC) 43.0
EVO (BBDC) 37.5 EVC (ATDC) -4.5
ICA (ATDC) 118.0 ECA (BTDC) 111.0

 

I ended up putting the XE262H in my car with Comp Cam K-kit (lifters, springs, etc). I also had the heads gone through for a basic valve job. The car seems to like the cam and now I am fine tuning it all...

 

Hey there Neighbor! Looking at the dates on these post it looks like you sure put some thought into it! Hope its a great choice for ya!

 

i stroked my ls-5 to 489. i went with the xe 274 solid flat tappet. ported and larger valves on stock heads. performer rpm intake, headers, 850 cfm custom smi q-jet. compression around 10.2 with forged pistons. this motor idles at 700 rpm and has plenty of torque. i think i could have went with the xe 284 but this thing has more torque and power than i will ever need.

 

...and it was the old timing chain nearly letting go that made me go ahead and do it... I hated tearing into an original motor but they all wear out some time... I saved the old worn-out cam anyway...put it in the Comp box in the back of the garage.

I am adjusting the APT on my carb by turning screw out 1/2 turn each time and trying it out. I went too far in last adjustment, now a bit bit lazy and rich and I got most but not all lean surge out before this last go around - the surge is back but a rich condition now... I will have to take the 48M rods out and turn the tips down to 0.026" like Lars suggests (using a drill, popsickle stick and fine sandpaper) if I want to dial in the part throttle and avoid a lean surge.