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Old 04-05-2005, 06:03 PM
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smart cam choice? opinions valued.

hi there, i've read alot of cam choice threads here, i think that i'm on the right track here. i am wondering which cam is the most logical choice for my set up? the cams i am looking at are ...
comp 280hr 224/224 525/525
comp xr276hr 224/230 502/510
comp xr282hr 230/236 510/520
gm hot cam 219/228 492/492---525/525 (1.6 rocker)
crane 222/230 509/528
gm zz4 208/221 474/510

this is '75 lt1 350 .030, 4:10, 2500 stall, air gap intake, vortec heads 600 lift springs(hopefully will have exhaust side ported for improved IvE %) carb not yet decided 600 cfm holley right now. the way i understand it is that i should be looking for low to mid 500 lift. which cam would make the most sense in this application and if you don't mind feel free to express why or why not you pick one cam over another. oh ya and for the record i think i prefer the the comp 280hr or xr282hr over the rest. thanks for taking the time to read my post and your opinions and comments are valued.
keith
as requested ... the car is a '76 camaro, i would like to get over 400 hp if possible, not sure of exact cr 9.5-10:1 ??? my current cam is 230 @ .050 and 480 lift. i am not too concerned with idle i like the lumpy idle. lol i do not beleive the block is decked.
thanks to all for reading.
keith

Last edited by classic keith; 04-05-2005 at 06:31 PM.
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Old 04-05-2005, 06:17 PM
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Well likes been stated many times in the previous post on this subject more info is needed.

Has the block been decked?

What type of pistons are you using?

What type of Horsepower are you lookin for?

Is idle quality and vaccum a concern?

What type of car or truck is it going into?

Answer those and I will be better able to give my opinion .

Doc
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Old 04-05-2005, 06:24 PM
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600 CFMs is too small for any of those cams. As posted above we need actual compression along with what your intended use for the engine is.

Since your springs are rated for .600", you may as well take advatage of them. Get a cam with some good lift numbers. I would get a cam with over .550" lift or change the springs.

Duration will help the Vortec heads flow better. How much depends on your computed compression. You don't want a cam bleeding away your idle, gas mileage, and vacuum any more than it needs to.
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Old 04-05-2005, 06:27 PM
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thanks doc, i do not believe the block has been decked, the pistons are either trw or sealed power(can't recall) not sure exact cr 9.5 -10 to 1???
i want to be able to get 400 + hp idle is no concern my current cam is 230 @ .050 480 lift (flat tappet) and the engine is in a '76 camaro. i hope this is enough info. please let me know if i can do more.
thanks keith

Quote:
Originally Posted by Docs91RS
Well likes been stated many times in the previous post on this subject more info is needed.

Has the block been decked?

What type of pistons are you using?

What type of Horsepower are you lookin for?

Is idle quality and vaccum a concern?

What type of car or truck is it going into?

Answer those and I will be better able to give my opinion .

Doc
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Old 04-05-2005, 06:31 PM
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As far as what would match the Vortec heads flow pattern the best, I would say the xr276hr or the xr282hr. These cams will also make its power right where the vortec heads like to. I beleive that the vortec heads will have a hard time keeping up after 6000 RPM on a 350. I would try to keep the overall RPM at or under 6000 RPM for your setup.

Adam
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Old 04-05-2005, 07:46 PM
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cam selections

Being that you are looking at a 6000 RPM ceiling with those heads, I would go with the crane 222/230 or the xr276. As far as carburetor goes, if you are planning to stay with 6000 RPM max, the 600 will give you all you need for that.
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Old 04-05-2005, 08:19 PM
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Ive read on here many times that vortec heads don't flow much over 500 lift. Am I wrong? I would keep the 230 deg .480 lift cam makes power all the way up to 6000 rpm. Why put a cam in an engine that makes power over your max RPM range
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Old 04-05-2005, 08:33 PM
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Quote:
Originally Posted by 67 Deuce 4 Me
Ive read on here many times that vortec heads don't flow much over 500 lift. Am I wrong? I would keep the 230 deg .480 lift cam makes power all the way up to 6000 rpm. Why put a cam in an engine that makes power over your max RPM range
you're right the vortecs don't flow much over 500 i think the flow rates on the exhaust side are a huge part of that. i've read that porting the exhaust side will help, if only a little bit. the comp cams i am looking at have rpmranges of 2000-5500/ 1900-5600/ and 2200-5800 going in the order that i have them listed in the first post. i like the last one because of my 2500 stall and max rpm of 6000. i was thinking that that was the approach i needed.
the crane cam of 222/230 509/528 has rpm range from 3000 - 6000. is the 3000 just a little too high for the 2500 stall?
thanks to everyone for their thoughts so far. i am trying to fully understand cams.
keith
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Old 04-05-2005, 08:40 PM
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stall vs cam rpm range

I dont think that havinga 2500 RPM stall is going to hurt your 3000-6000 cam, and it may even be a boon when it comes to launching. May years ago I ran a car with a 2000 RPM stall and the cam was 2500-5500. Made for excellent launches, being that as soon as I started moving, I was into the cam, and didnt waste any power .
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Old 04-05-2005, 08:43 PM
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I dont think so, I belive the stall you have is a good choice! ....Ed. I run the 280 magnum in my car, the same cam you have now. 388 cu in.I have a 1800 to 2200 stall. works perfect.
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Old 04-06-2005, 11:38 AM
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Quote:
Originally Posted by Max Keith
I dont think that havinga 2500 RPM stall is going to hurt your 3000-6000 cam, and it may even be a boon when it comes to launching. May years ago I ran a car with a 2000 RPM stall and the cam was 2500-5500. Made for excellent launches, being that as soon as I started moving, I was into the cam, and didnt waste any power .
but the cams i seem to like the most... being the comp 276/282 have rpm ranges of 2000-5500 rpm. are you saying that a cam with an rpm range of 3000-6000 would be a better cam for this application that the 2000-5500rpm.
again i'm looking to make 400 + hp if possible and the car is a street/strip car. idle and gas mileage arre not an issue. i'm strictly looking for a good solid fit for my combo. if that means a cam in the 3000-6000rpm rather than the 2000-5500rpm thats fine.
thanks
keith
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Old 04-06-2005, 01:24 PM
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cam choices

Being somewhat conservative on cams, in that I prefer to error on the small side, The 2000-5500 maybe your better option. There are so many other variables, like rear end gearing, vehicle weight, tires, etc, you get the point.
As was mentioned by another poster, the cam you have at the present sounds pretty much in your ballpark, now.
Since I dont know much about the heads you are running, that also comes into the equation.
I am giving you the figures on my 351W, as despite what a lot of detractors may want to say, there isnt that much of a difference in the performance capabilities of a 350 and a 351.
I have a 351W, with out of the box, Twisted Wedge heads, 9.4:1 compression, 230/235 degree, .510/.515 lift, 106 degree lobe separation, solid lifter cam, Edlebrock Performer intake, 600 CFM Holley carb, Mallory Dual point, 1 5/8ths primary headers.
My engine actually dynoed at 398 HP@ 5500 RPM, with closed exhaust, and 410 HP@ 5500 RPM with open headers.
Going to a 750 only brought me up to 401 HP at@ 5500 cloed, and 417@ 5500 open.I elected to stay with the 600 for the sake of driveability, since I saw no power gains below 4000 RPM, by going to the larger carb.
I dont think your Vortec heads will out breath the Twisted Wedges with out alot of massaging. That being the point, regardless of what cam you run, I would honestly say, you may well peak out at around 365-375 HP, and you may have to turn 6000 to do it. Locating a cam with a narrower lobe separation my well be the way to go, as they generally produce more peak HP than does a wide lobe separation cam, but the wider separation cams usually have a flatter torque curve.
With the rest of your setup, in my opinion, your heads are what may be your limiting factor on hitting your 400 HP goal, particularly with your compression ratio.
Another thing to consider, if you are able to build bucket loads of torque on the lower and mid ranges, with your engine, you will be better served than trying to turn it a kazillion RPM.
Just my 2 cents worth.

Last edited by Max Keith; 04-06-2005 at 01:30 PM.
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Old 04-06-2005, 03:55 PM
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thanks for your honest evaluation of my set up. . i like to try to see things from the "devils advocate" approach. i still have the question about the rpm ranges. comparing the 2 different rpm ranges ... 2000-5500 vs 3000-6000, which rpm range will help make better et's and power with my set up. if the stall is 2500 how does this affect a cam with power band starting at 2000 rpm. would i not want the power band to start just after the stall rpm rather than before it. if so i think i am understanding why you suggest the cam i am using already for my combo. i've heard the comment before to error on the small side. i will take your advice on seperation but i agree if you can't get the peak hp, gobs of bottom and mid torque combined with 4:10 gears might be the best i can do with what i have.
thanks again, hope i'm not frustrating you too much.
keith
Quote:
Originally Posted by Max Keith
Being somewhat conservative on cams, in that I prefer to error on the small side, The 2000-5500 maybe your better option. There are so many other variables, like rear end gearing, vehicle weight, tires, etc, you get the point.
As was mentioned by another poster, the cam you have at the present sounds pretty much in your ballpark, now.
Since I dont know much about the heads you are running, that also comes into the equation.
I am giving you the figures on my 351W, as despite what a lot of detractors may want to say, there isnt that much of a difference in the performance capabilities of a 350 and a 351.
I have a 351W, with out of the box, Twisted Wedge heads, 9.4:1 compression, 230/235 degree, .510/.515 lift, 106 degree lobe separation, solid lifter cam, Edlebrock Performer intake, 600 CFM Holley carb, Mallory Dual point, 1 5/8ths primary headers.
My engine actually dynoed at 398 HP@ 5500 RPM, with closed exhaust, and 410 HP@ 5500 RPM with open headers.
Going to a 750 only brought me up to 401 HP at@ 5500 cloed, and 417@ 5500 open.I elected to stay with the 600 for the sake of driveability, since I saw no power gains below 4000 RPM, by going to the larger carb.
I dont think your Vortec heads will out breath the Twisted Wedges with out alot of massaging. That being the point, regardless of what cam you run, I would honestly say, you may well peak out at around 365-375 HP, and you may have to turn 6000 to do it. Locating a cam with a narrower lobe separation my well be the way to go, as they generally produce more peak HP than does a wide lobe separation cam, but the wider separation cams usually have a flatter torque curve.
With the rest of your setup, in my opinion, your heads are what may be your limiting factor on hitting your 400 HP goal, particularly with your compression ratio.
Another thing to consider, if you are able to build bucket loads of torque on the lower and mid ranges, with your engine, you will be better served than trying to turn it a kazillion RPM.
Just my 2 cents worth.
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Old 04-06-2005, 04:18 PM
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I think you are splitting hairs. The cam you have is about the same as all the rest you are looking at. That is, you will not notice a big difference.

Instead you should invest in a good set of 1.6 roller rockers, a performer rpm intake, and a 750 cfm Holley.

You should be able to make 400 hp with the vortec heads and you current cam if the exhaust and intake are free flowing. I have seen many 400hp vortec headed dyno runs with a cam of your current size.

Do a little bowl smoothing to gain a good amount of extra hp. Concentrate on the valve seat/head interface.
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Old 04-06-2005, 04:35 PM
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thank you for your post. that work was done and i now am going to open up the exhaust side. the cam issues i have are more less in going from the hyd flat tappet cam i have now to a roller cam. i was planning on the 1.6 rockers until i saw that most of the roller cams have lift into the 500's already and then thought the 1.6 might push me alittle too high. i do have a 750 vac secondary which needs a rebuild, but it's there to use if needed.
thanks again.
keith
Quote:
Originally Posted by 454C10
I think you are splitting hairs. The cam you have is about the same as all the rest you are looking at. That is, you will not notice a big difference.

Instead you should invest in a good set of 1.6 roller rockers, a performer rpm intake, and a 750 cfm Holley.

You should be able to make 400 hp with the vortec heads and you current cam if the exhaust and intake are free flowing. I have seen many 400hp vortec headed dyno runs with a cam of your current size.

Do a little bowl smoothing to gain a good amount of extra hp. Concentrate on the valve seat/head interface.
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