Calling All Cam experts!!

[69CamaroRacer]

Well I have just rolled the 500 mile marker on my new 383 and I am left wondering... I just don't think that the power levels I was looking for are there. I wanted a 500hp 500tq street monster but the seat of the pants tells me it is not there. So I was wondering if the cam I chose might not be the best.

Here are the specs on the combo

383 10.5-1 comp
AFR 195 heads.. ported flow 278in 210 ex
Comp Magnum hydrolic Roller Cam #12-450-8
750 Holley HP series carb. (stock out of the box)
Air Gap intake.
Th 350 with Caon 3000 converter
12 bolt w/ 3.55 cogs
For a fuel system I ran -8 An from a sump in the tank
to the mech fuel pump. It is an Edelbrock 110 gph.
THe exhaust sys is a 1 3/4 long tube headders in to a 3.5 collector and 3 in system that has 40 series flows and an x-pipe.

Now the engine still needs some tuning.. it has a date with the dyno soon and only that will tell. If I had to guess I would say I am somewhere near 375- 400hp. THe engine runs and idels fine. It pulls hard to about 6300 and then the cam runs out. I have the rev kit so no valve float. I know that tuning can give allot so I am not gonna change anything till I get a good tune but I was just day dreaming here looking for more power. Also I need to get my fuel pressure gague hooked up so I can see if there is a pressure drop on WOT. I thought about a Comp cams XE series cam because of their more agressive ramp speeds. Ok below you will find the specs for the cam I have.

Here are the specs from the cam card.
Gross lift .560in 560 ex
duration at .006 Tappel Lift 286 in 286 ex
Valve timing INT 37* BTDC 69* ABDC
EXT 77* BBDC 29* ATDC
The cam has a 106 Intake centerline.

Intake Exhaust
Duration at .050 230 230
LSA 110*

Ok so what would the perfect cam be for my set up? THe only guide lines that I have is that it be a Hydrolic Roller.

[andrewb70]

Before you start thinking about swapping parts get it tuned perfectly. If your A/F ratio is not right or your timing is not right, you can easily be loosing 50HP. It's actually pretty hard to get 500HP out of a 383. We had a ZZ383 on the dyno at Holley and even with a very radical cam it did not hit the 500HP mark.

Andrew

[Travis B]

Before you start thinking about swapping parts get it tuned perfectly. If your A/F ratio is not right or your timing is not right, you can easily be loosing 50HP. It's actually pretty hard to get 500HP out of a 383. We had a ZZ383 on the dyno at Holley and even with a very radical cam it did not hit the 500HP mark.

Andrew


Andrew what heads were on it and what cam did it have in it? Roller or flat tappet solid or hydrualic?

thanks in advance

[andrewb70]

Andrew what heads were on it and what cam did it have in it? Roller or flat tappet solid or hydrualic?

thanks in advance

It was a GM crate engine, ZZ383. Hydraulic roller cam and whatever heads come on that engine. WE ran a series of cams with the last one being around 230-240 duration at .050" and about .54x lift. They had a Vortec bolt pattern. Here are more details on it:

http://www.paceparts.com/index.asp?PageAction=VIEWPROD&ProdID=73193

Andrew

[Travis B]

It was a GM crate engine, ZZ383. Hydraulic roller cam and whatever heads come on that engine. WE ran a series of cams with the last one being around 230-240 duration at .050" and about .54x lift. They had a Vortec bolt pattern. Here are more details on it:

http://www.paceparts.com/index.asp?PageAction=VIEWPROD&ProdID=73193

Andrew


Thanks for the link......

[JayBird]

Hey, I'm no cam expert, but I do have my own personal experience and dyno time on my engine with a comp hydro roller cam. I have close to the same spec cam as you on a 355 sbc and mine made 470hp and 460 tq. I suspect yours will be in the 425-450hp range when properly tuned.

Here's what I have found out about hydro roller cams. The rpm limit is around 6000-6200. My limit was 6200 with comp cams 929 springs which is on the heavy side as far as seat pressure, etc for hydro lifters. After speaking with comp I switched to the bee hive springs which bumped up the rpm to 6600-6700. Anything after that on the engine dyno shows vallve float. You say the valves are not floating, but I would bet they are after 5800-6000. I also think (my personal opinion) that the rev kit does not increase rpm limit, it can help lifter stabilization, but that doesnt necessarily mean more rpm.

I am in no way putting down hydro rollers. They work great for what they are meant for. I am currently switching to a mech roller so I can turn a few more rpms.

I think the cam you have is a good choice for what your intentions are. My only suggestion would be to chassis dyno it or engine dyno it if you could and change to the bee hive springs and you would see exactly where your rpm limit is and also be able to detemine where valve float occurs. I can drive my car and turn it to 7000, with no audible signs of valve float, but per the dyno I know after 6700, in fact it is floating the vlaves. At 7200, I do then hear signs of valve float in the car. I have only done this once. This is not something you would want to consistantly do.

Again, once properly tunedm, I think you will be happy with the power the hydro roller makes, just you cannot turn them higher rpms like a solid roller.

my 2 cents,

Feel free to ask me questions if you like. I am no engine builder, but I have spent alot of dyno time and $$ with my engine builder finding these things out.

Jay

[Travis B]

Hey, I'm no cam expert, but I do have my own personal experience and dyno time on my engine with a comp hydro roller cam. I have close to the same spec cam as you on a 355 sbc and mine made 470hp and 460 tq. I suspect yours will be in the 425-450hp range when properly tuned.

Here's what I have found out about hydro roller cams. The rpm limit is around 6000-6200. My limit was 6200 with comp cams 929 springs which is on the heavy side as far as seat pressure, etc for hydro lifters. After speaking with comp I switched to the bee hive springs which bumped up the rpm to 6600-6700. Anything after that on the engine dyno shows vallve float. You say the valves are not floating, but I would bet they are after 5800-6000. I also think (my personal opinion) that the rev kit does not increase rpm limit, it can help lifter stabilization, but that doesnt necessarily mean more rpm.

I am in no way putting down hydro rollers. They work great for what they are meant for. I am currently switching to a mech roller so I can turn a few more rpms.

I think the cam you have is a good choice for what your intentions are. My only suggestion would be to chassis dyno it or engine dyno it if you could and change to the bee hive springs and you would see exactly where your rpm limit is and also be able to detemine where valve float occurs. I can drive my car and turn it to 7000, with no audible signs of valve float, but per the dyno I know after 6700, in fact it is floating the vlaves. At 7200, I do then hear signs of valve float in the car. I have only done this once. This is not something you would want to consistantly do.

Again, once properly tunedm, I think you will be happy with the power the hydro roller makes, just you cannot turn them higher rpms like a solid roller.

my 2 cents,

Feel free to ask me questions if you like. I am no engine builder, but I have spent alot of dyno time and $$ with my engine builder finding these things out.

Jay


what heads are you running??? How much compression? What solid roller are you going to go to?

[TurboLark]

I personally hate single pattern cams for just about everything out there. A good dual pattern would help usually. With a 383 you can us a little bit larger cam. You didnt say at what lift the head flow was at, but normally I like to run .025-.040" more lift than the peak head flow(the valve goes past that point twice this way). For duration I would be looking at 232-236deg int and 238-244 deg exh at .050. something in the 110-112 lobe seperation would be nice. In this situation, i would prefer to use a solid roller to avoid the potential valve float problems.

Main thin at this time is to get fully tuned to see where you are at, and then determine if you are happy with it or not.

[Lowend]

The cam selection isn't bad, the intake to exhaust ratio is about .75 - .80 is considered "perfect" so you may see a little power from a little more duration on the exhaust side.... BUT there is a world of power to be had from a fine tune. My old dyno guy once found 200RWHP on a car without swapping any parts (right jody ;) )
I would definately do some dyno tuning before swapping ANY parts on the combo, its pretty well matched.