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-   -   Cam choice,, Please help!! (http://www.hotrodders.com/forum/cam-choice-please-help-57597.html)

Lthompson 02-06-2005 08:05 PM

Cam choice for 383,, Please help!!
 
Ok, heres the deal im trying to pic a cam that will give me the best usable power in my combo. I want the biggest cam i can get that will give me the best overal power and torque that i will really be able to feel. I would like to have a high torque number while still having the horsepower to push it. Its going into a 79 camaro, a rather heavy car so i need the torque. It will be driven on the street mainly, but i want it to be the meanest i can get it while still being streetable. And i want to be happy with my results. Im undecided between 3 cams. the XE274, XE284, or the 286 magnum. Im going to be running 1.6 rockers as well. Heres the specs for each cam

274-- 230/236 at .050 .478/.490 lift
284-- 240/246 at .050 .507/.510 lift
286-- 236/236 at .050 .490/.490 lift

Heres what its going into..

383
AFR 180cc heads, Flow 240 cfm at .400 and 255 at .500
10.5.1 compression
6 in. rods
1.6 pro magnum rollers
demon 750 carb
RPM air gap intake.
3000 rpm stall converter
3.73 gears

I want as many opinions as i can get so everyone,,, PLEASE HELP ME!! Maybe someone could even run those cams through a "good" dyno program and throw me some estimated numbers. It would be much appreciated. thanks a million and good hotrodding to all!

bracketeer 02-06-2005 08:53 PM

I don't agree with your combo but....
 
Why 1.6 rockers? Buy a bigger cam (a 5.25 cam cost the same as a .490) and use 1.5 rockers and stock length push rods. Its a whole lot cheaper and works better.

Since I am forced to pick one of the three cams you are deciding on. I would take the XE286.

Lthompson 02-06-2005 08:57 PM

Im using 1.6 rockers because thats what i already had and they were brand new originally purchased for a seperate engine. and i meant 6 in connecting rods. Push rods will be stock length, thanks again for any more help.

Deuce 02-06-2005 08:59 PM

:D


I suggest calling the Camshaft company of your choice and telling them what you want....with your specs.

They will do a LOT better job than most anyone here.........Because they are professionals. And they want you to be happy......and refer more business to them.

I have always have great results when going with the Camshaft manufacturers choice......

:D

bracketeer 02-06-2005 09:05 PM

pushrods
 
Your pushrods will not be stock length with 1.6 rockers. You will have to figure out the length yourself. 1.6 rockers change the entire valve train geometry.

KeithB123 02-06-2005 10:35 PM

WOW, you have a great combo to start with! Textbook!

All 3 cams are too big for a street set up, Unless your compession is bumped up. I have the 274 right now. It is big for the street! It can be run and driven on the street but the power is on the top end. You need a small cam for the street, We ALL think or thought a bigger cam will make more power.........top end.

Go with the Extreme 262!

bracketeer 02-06-2005 11:21 PM

I'm not a professional or stupid.
 
Well, I would have to agree with Keith. All the cams are too big for 1.6 rockers.

My suggestion was 1.5 rockers with the .490 cam.

I based this choice on the Edelbrock perf/rpm 64 cc head which recommends the .488 cam. The Edelbrock head only carries a 170 cc runner which is smaller than the 180 cc runner he is using. The 64cc head gives the same compression at 10.5 to 1. The .488 cam recommends 2800+ stall. Which is basically what he has. Thus, the .490 was the best choice.

Since he is determined to use the 1.6 rocker and a Comp cam. We will deduct the 7% gain from the 1.6 rocker. So, the .490 cam divided by 7% leaves a .4579 cam. Comp cams closest cam is the XE262H which has a .462 lift. Which is exactly what KeithB123 suggests.

My preference:
Crane cams 286H06
.465 lift, which is where we agree you want to be.
286 duration, which is longer than the XE262H
(duration is barely affected by the 1.6 rocker, only the lift).
http://cranecams.com/?show=browsePar...tType=camshaft

firestone 02-07-2005 02:02 PM

I did a little looking, to see what cams are being used with the 180cc heads. I also learned a little more about why it is better to use a single pattern cam instead of a dual pattern with a set of heads that flow like the AFR's while reading the first article. The first combo below is used on a 350, but remember that matching a head and cam has very little to do with what the size of the motor is. A matched setup on a 350 will be equally as matched on a 383, just with a lower powerband.

this combo (a 355) made 425 hp at 5800 RPM with a 224 @.050 cam ( for the most part duration is what determines your powerband) I think a slightly larger cam would have made a little more hp without sacrificing much torque.

http://www.chevyhiperformance.com/te.../148_0306_355/

Here is a page from the AFR website with several different cams in 383's with the 180cc heads. Notice that the largest cam that they used with the 180cc heads was the 12-432-8 (XR282HR)which is a hyd roller with 230-236 dur @.050 and .510 .520 lift. This cam is rated to 5800 RPM. This motor made 491 hp at 5500 RPM which is about right considering that you will drop 200-300 RPM because of the motor being a 383 rather than a 350 which the parts are based on. If you look at the XE274H cam it has 230 236@.050 dur and .487 .490 lift. If you added the 1.6 rockers to that, you would be at .517 .520 lift. these specs are almost exactly that of the XR282HR. Also notice that they did not bump up to the 12-433-8 (XR286HR 236 242 @.050 .520 .540 lift) until they started using the 195cc heads.

http://www.airflowresearch.com/dyno/chevy_dyno.htm

They only other thing I would consider would be running the single pattern 280H cam (230 230@.050 .480 .480 lift). with the 1.6 rockers that would put the lift at .510 .510. This would also work very well.

Here is the comp page with all the cams I talked about

http://www.compcams.com/Technical/Cu...ML/128-169.asp

Adam

bracketeer 02-07-2005 02:42 PM

roller cams
 
Roller cams are nice but expensive. 3 out of the 5 cams firestone mentions are rollers. Take that into consideration.

rumpity_z28 02-07-2005 03:04 PM

Quote:

Originally posted by Deuce
:D


I suggest calling the Camshaft company of your choice and telling them what you want....with your specs.

They will do a LOT better job than most anyone here.........Because they are professionals. And they want you to be happy......and refer more business to them.

I have always have great results when going with the Camshaft manufacturers choice......

:D

:thumbup: I agree thats why we pay the big bux for these products because of R&D and free support i phoned compcams a couple of times and its hard to shake those guys of the phone hehe they just love talkin :) and know what there talkin about

johnsongrass1 02-07-2005 03:06 PM

You wouldn't suppose AFR would inflate their numbers for argument's sake would ya?


Don't believe much of what you read. Even if you read in ten different places.

firestone 02-07-2005 04:39 PM

Those motors do have hyd roller cams, so your motor will not make quite as much hp, but my main point was to compare the size of the cams they were using not necessarily how much hp they were making.

They could be inflating the numbers, and so could all of the other magazines that get similar numbers. I don't have any reason not to believe them though until I see something on the contrary.


Adam

bracketeer 02-07-2005 04:50 PM

I am amazed
 
Quote:

They will do a LOT better job than most anyone here.........Because they are professionals.
Can you believe a moderator actually posted that. Lets all just call the tech people and not bother coming to hotrodders.com

1BAD80 02-07-2005 06:26 PM

Notice he is not a Moderator ON THIS Forum or a professional or even knows who is one on this Forum.
I would recommend a CompCams Magnum 280H .
Maybe because I run in the sportsman class in top alcohol dragster, Im probably wrong because its not a Pro class.
:( :pain:

Deuce 02-07-2005 07:22 PM

Quote:

Originally posted by 1BAD80
Notice he is not a Moderator ON THIS Forum or a professional or even knows who is one on this Forum.
OK.........who is a professional camshaft advisor employee on the board?

And I have cut camshafts.........in the past.

I did not design them........just cut them........

And I stand by my statement.........


They will do a LOT better job than most anyone here..........Because they are professionals.

How many here work for a camshaft company?

:D


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