iroc.86

i would like to upgrade my cam because the one that is in my motor now is
a bit conservative for a 383 and it has my dcr up a bit high calc. at 9.9
here are the specs for my current cam its a lunati voodoo 60103

• Advertised Duration (Int/Exh): 268/276
• Duration @ .050 (Int/Exh): 227/233
• Gross Valve Lift (Int/Exh): .489/.504
• LSA/ICL: 110/106
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 1800-6200

im not having any problems with this high dcr i am just looking for more power
and since i put in the 9" w/3.90 im crossing the trap around 6000-6300 rpm
but it seems like the motor is peaking around 5600-5800. my botom end is rated to 7500 so i should be good there.

im thinking of this cam from lunati and am wondering what kind of gains i might expect, im thnking around 500fwhp. anyways the specs are as follows.

• Advertised Duration (Int/Exh): 273/279
• Duration @ .050 (Int/Exh): 243/249
• Gross Valve Lift (Int/Exh): .578/.585
• LSA/ICL: 110/106
• Valve Lash (Int/Exh): 016/016
• RPM Range: 2600-7000

Stekman

Most cam powerbands as listed by manufacturers are given based on a stock displacement. I think Comp lists there's as a rough idea based on the 350cid platform. Rule of thumb is a couple hundred RPM difference per displacement change. A 305 would be around +200 rpm, 350 to 383 would drop a couple hundred. That said, yes, your current powerband sounds right.

If it's a street motor, my suggestion would be to keep it hydraulic. Unless you run constant 4k-7k+, you won't notice any difference between a solid of that size versus a comparable hydraulic. They're not worth the price of changing out the entire valve train for what very little is actually gained. Especially with the way companies grind hydraulic ramp rates these days.

Actual specs look fine.

Orr89RocZ

iTrader: (20)

specs would be nice for a hyd. 4.11 gear too. That cam will peak near 6400-6500.

Are you sure your DCR is 9.9?? that seems way high. Whats your static?

iroc.86

well i think i will see if i can get those specs ground on a custom cam only hyd instead of solid.

and yeah im pretty sure the dcr is correct i used the calculator on the kb piston website . specs on my engine are

64cc heads
flat tops w/7cc rellife's
.041 head gasket
4.166 gasket bore
block zero decked
3.750 stroke
5.7" rod
ivc of 39.5 abdc
yeilds
10.7:1 static
9.994:1 dynamic

88IROC350TPI

Call Cam Motion and get a custom one ground, trust me you won't regret it.

Orr89RocZ

iTrader: (20)

Whats the valve events on that cam?

iroc.86

the events are

evc 2.5
evo 50.5

ivo 7.5
ivc 39.5

icl 106
lsa 110
4* adv built in

ps. your car is my biggest motivation

Orr89RocZ

iTrader: (20)

Thanks! but its nothing special. Buy my cam and you basically have my setup

Any cam in the 230ish duration range with alot of lift will be awesome on your setup. Get that DCR down inthe mid low 8's and should make power

iroc.86

thats the thing im having trouble finding a cam that will bring it down that low the one im looking at will drop it to 9.7 i need something with a ivc of around 60-70* i belive. car runs good now pulls hard best motor run was a 12.47 @ 108 on a 1.73 60fter but i think it should run mid 11's with minimal work

Orr89RocZ

iTrader: (20)

yeah you definately need abit more cam.

i calculate dynamic to be 8.95 to 1 with that cam. Using your above specs and IVC of 60 degrees, which is the advertised closing point. The 39.5 is the closing at .050". use advertised for DCR calcs

Still pretty high. Your right tho, you want closing around 70 degree range to get lower 8's. 70 should give 8.3 to 1 DCR


Comp's 240/246 hyd tappet cam, XE284H will do well. 69 degree closing point. That should peak near as high as my motor did and should give you some getup and go. Has abit less overlap than my current roller cam so it should be tuneable, even tho flat tappets i have heard arent quite as smooth as a roller at idle and low rpm. Doesnt matter tho i still think it should be tuneable because I could have gone alot bigger and still been fine

iroc.86

im thinking this might be better choice its 2 steps up from what i have now

voodoo 60105

• Advertised Duration (Int/Exh): 284/292
• Duration @ .050 (Int/Exh): 241/249
• Gross Valve Lift (Int/Exh): .525/.546
• LSA/ICL: 110/106
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 2500-6600

Orr89RocZ

iTrader: (20)

Thats pretty comparable to what comp cams offers. That be a nice choice for street strip car.

iroc.86

hey justin, who makes your cam? also do you think the diff between roller and flat tap would be negligible? by the way whats your race weight?

since i put the 9" in i gained 105lbs car weighs 3555 with me in it.
so by my time it should be around 350-360 whp

Orr89RocZ

iTrader: (20)

my cam was a custom grind spec'd by bret bauer but the grind came from comp cams but from their lobe catalog i dont think its a comp cams lobe.

my car was 3450 or so with me in it. At your weight i'd say more like 340whp. Cam swap could/should get you closer to 370 with tuning but then again, its hard to say. I would think it would make around that power if not more with a cam like that 241/249 or similar. If it will peak near 500 rpm higher than what your current cam does, then it should really make power on the top end.

They say around mid 220's duration the roller tappets start to make more power and are smoother running. 240 is a decent sized hyd flat tappet, so a similar roller i would expect to make abit more power but how much? I have no idea.

89formula350b2l

iTrader: (11)

Well well well....another 383 HSR......your times and mine are purdy darn close man. i have the xr276 BUT Thursday I got my LE custom cam.....You cannot go wrong with custom cam.....i mean it is made for your specific car! Besides....Lloyd only charges $300....i believe its actually cheaper than buying an "off the shelf" cam from comp cams/crane/ ect

good luck man!

iroc.86

are you selling it? since you are going tt right?

Orr89RocZ

iTrader: (20)

yeah its a hydraulic roller tho but its for sale I already have my new turbo cam laying here which is also a great grind for a n/a motor

327Chevy

orr89rocz is right in post #10.

I also looked at the Lunati 60103 cam card. Yes it does say 39.5 ABDC IVC. But that is at .050" lift, not the IVC @ "advertised / .006" lift" that should be used in DCR calcs.

How do we know that this is at .050"? Because looking at the card for the intake lobe open @ 7.5 degrees BTDC, stay open all through the downstroke (180 degrees) then close @ 39.5 degrees ABDC. What does this add up to? 7.5 + 180 + 39.5 = 227 degrees duration, the .050" duration of the cam as per lunati.

Instead, to find the "advertised" IVC (that should be used in DCR) use the lobe centerline of 106 degrees plus the advertised duration / 2 (since it is given in cam degrees). that is 268 cam degrees intake duration / 2 = 134 crank degrees. So the IVC at advertised duration is 106+134 = 240 degrees past TDC or equally 60 degrees ABDC.

Use 60 ABDC instead of 39.5 for your IVC. (I know orr89rocz already said this) This is going to put your DCR closer to the 9.0-9.1 range. This is from my little excel program, I haven't verified per KB.

Also this is good article for what DCR is safe to run with various thermostat and octane combinations. See the chart with the three lines.

http://www.popularhotrodding.com/eng...eze/index.html

iroc.86

b

iroc.86

is it for an oe roller block or is it a retro-fit?

iroc.86

hey orr, guess you didnt catch this? i might be interested in that bump stick!

Orr89RocZ

iTrader: (20)

i replied above but i missed that part. my cam is a hydraulic roller for an OE roller block. I have a guy somewhat interested in it but he's unsure of his intake and head setup so i'm not gonna sell it til he's sure

If you get this cam i can give you the tune for it and it should be close on your motor as its comparable to my old 383