What cam should I use? - Team Camaro Tech
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post #1 of 20 (permalink) Old Jan 10th, 13, 07:58 PM Thread Starter
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Wayne
 
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What cam should I use?

I'm rebuilding a stock 69 SS 300hp 350 and the cast pistons will be 30 over, 041 194 64cc heads, 350 turbo, 308 gears, stock manifolds and Rochester carb. It has power brakes and steering but no AC. I want to keep the original cowl induction set up. I've been asking mechanics and also searching information on this forum to learn more about how the cams work. Here's what I want: an engine that has more horse power, but I don't want to use a stall converter. If the cam makes the engine idle a little rough but is good for the street that's ok. I guess to keep it simple, I want it to get up and go and not hurt the engine but would run smooth in normal driving. It's not going to be run down the track but if I feel the need for speed?

Some suggestions have been an Elgin 465/488 with lobe separation angle @ 112 or a 453/480 @ 112.

Another suggestion was a cam with 470 and 106-108 lobe separation angle.

I don't care so much what brand to use so long as it is made good.

I think I'm starting to understand how they work but there's enough info that it's still confusing. The cam does make a difference in hp doesn't it?

Any suggestions or tips would be appreciated. And if there are any youtube videos of some similar cams let me know.

Thanks, Wayne
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post #2 of 20 (permalink) Old Jan 10th, 13, 08:05 PM
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Michael Gekko
 
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Re: What cam should I use?

What you are posting are the lift numbers at the valve, a better indicator of the nature of the cam would be duration numbers @ .050 lift imo.

I would contact the folks at Bullet cams at 662-893-5670, they can help you pick the right grind for your application better than most anyone else.

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post #3 of 20 (permalink) Old Jan 10th, 13, 08:31 PM
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Re: What cam should I use?

The Comp Extreme Energy 262 would fit the bill nicely. Isky 262 SuperCam would also be a nice fit. Those 3.08 gears will limit you from going with a bigger cam than those two.

Quote:
Originally Posted by Eleanor's Nemesis View Post
What you are posting are the lift numbers at the valve, a better indicator of the nature of the cam would be duration numbers @ .050 lift imo.

I would contact the folks at Bullet cams at 662-893-5670, they can help you pick the right grind for your application better than most anyone else.
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post #4 of 20 (permalink) Old Jan 12th, 13, 11:49 AM Thread Starter
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Re: What cam should I use?

I haven't had time to call anywhere yet and this is the weekend. I appreciate the responses. Just so I can get a better understanding of the differences in cam specs and what they do I will give the complete info on this Elgin cam.

The part # is E1166. Lift: .453/.480 Duration: 282/294 Duration @ .050":216/228 Lobe separation 112 LC

This one sounds like it has more power than stock but doesn't need a stall convertor. And what I am understanding is that the 112 lobe separation may not be as good as 114 as far as running smoother. Is that right? Although 112 may not be that much different.

Would this cam work okay like the CompCam 262 mentioned? I'm trying to find out as much as I can so I will not be disappointed in the cam I choose.

I know that using the stock exhaust manifolds will probably hurt the performance some too. FYI, the compression was 10.25:1 according to the books. My goal is to look as stock as possible and still have a better performing engine.

Thanks
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post #5 of 20 (permalink) Old Jan 12th, 13, 12:24 PM
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Re: What cam should I use?

Not really 10.25:1. More like 9.5-9.75. The smaller the duration at .050, the more the powerband of the cam is on the low end of the rpm range. Idler is smoother also. Comp had graphs of the Extreme Engergy powerbands. Peak horsepower was practically the same, it just moved up or down in the rpm range. That Elgin cam is very similar to the specs of the EX-262 and the Isky I spec'ed. Lobe seperation angles are like everything else in cam shaft choice, a compromise. Here's a link that explains the effects of narrow vs wider angles. http://www.compcams.com/Technical/FAQ/LSAproperties.asp

Comp EX cams and Lunati Voodoo cams have very aggressive ramp rates. This can cause valvetrain noise. Some people like them, some people like the smoother ramp rate cams. Do your homework. Converter size and rear gear ratio are going to be your deciding factors. Figure your engine CR to be about 9.7 if it is stock and never had the block machined and factory pistons and heads.
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post #6 of 20 (permalink) Old Jan 12th, 13, 12:32 PM
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Re: What cam should I use?

Here is my suggestion based on your set-up: http://www.lunatipower.com/Product.aspx?id=1982&gid=287

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post #7 of 20 (permalink) Old Jan 12th, 13, 02:00 PM
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Re: What cam should I use?

This one is perfect...http://www.lunatipower.com/Product.aspx?id=1983&gid=287
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post #8 of 20 (permalink) Old Jan 12th, 13, 02:14 PM Thread Starter
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Re: What cam should I use?

The CR shows 10.25:1 in an old 1969 Motors auto repair manual is where I came up with that. It will have the original heads with new 30 over pistons. So it sounds like I will have about 9.5:1.

I am going to use the stock torque converter and the 308 gears.

I think I'm understanding now. For example, using another Elgin cam, it is part #922. It has .433/465 lift, .050" 214/224 duration and 112 LS. So this one has a little more torque at low end and a little less high end power than the 216/228? And the higher the lift is more powerful but makes the engine run rougher and is what determines the use of a stall converter.

And the ramp rates on the 2 other cams mentioned can cause valve train noise. I take it that the noise isn't damaging anything it's just a more aggressive noise.

I appreciate the suggestions and information.
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post #9 of 20 (permalink) Old Jan 12th, 13, 04:39 PM
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Re: What cam should I use?

You MUST be realistic with the RPM powerband. Will you ever hit 5500 RPM's??? How often??? I would keep the RPM range either, idle to 5000, or 1,000 to 5500 RPM's. Just my .02.

I had the Comp XE (Extreme Energy) cam, yes the valvetrain was a little noisy, did not bother me at all.

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post #10 of 20 (permalink) Old Jan 12th, 13, 07:34 PM
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Re: What cam should I use?

I run the Extreme Energy 262 with my engine which happens to be a 1970 300 hp 350 out of a Nova. .030 over forged pistons, pocket ported 041 heads. Since you are boring your engine, you will have a perfect opportunity to have the block decked to zero, cc the cumbustion chambers and valve relief in pistons and figure your compression ratio exactly. Yes, the factory manual shows 10.25:1 but that is not what they came out to in real life. You will be able to get your squish/quench right in the magic .040-.045 range.

You'll also note that the Lunati cam recommended is right there with the EX 262 and the Isky. Keep your cam specs in the ballpark of the cams that I and others have recommended and you'll be a happy camper. Don't overthink this. You're goals are a mild build and these sticks will fit the bill.
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post #11 of 20 (permalink) Old Jan 12th, 13, 07:47 PM
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Re: What cam should I use?

I'm not sure that the factory valve springs can handle that much lift. And if they are original 40 year old units I would definately recommend replacing them.

The higher valve lift doesn't really create the rough sounding idle...you get that with larger duration numbers and as lobe separation angles decrease the idle tends to get rougher too. One of the best ways to judge the characteristics of a cam profile is to know what the duration is @ 50 thousandths lift. That gives a better idea of how long the valves are off their seats and how 'fast' the ramps are. There is more to consider but the .050" duration number gets you in the ballpark so to speak. A lot of things go into determining which torque converter should be used, but typically as the .050" duration number gets bigger the more a performance converter should be considered. The Elgin cam would probably work better than the other one with 3.08 gears and a stock torque converter. Make sure the valve springs are at least .030" from coil binding with your new cam though.

Quote:
Originally Posted by 69ndpce View Post
The CR shows 10.25:1 in an old 1969 Motors auto repair manual is where I came up with that. It will have the original heads with new 30 over pistons. So it sounds like I will have about 9.5:1.

I am going to use the stock torque converter and the 308 gears.

I think I'm understanding now. For example, using another Elgin cam, it is part #922. It has .433/465 lift, .050" 214/224 duration and 112 LS. So this one has a little more torque at low end and a little less high end power than the 216/228? And the higher the lift is more powerful but makes the engine run rougher and is what determines the use of a stall converter.

And the ramp rates on the 2 other cams mentioned can cause valve train noise. I take it that the noise isn't damaging anything it's just a more aggressive noise.

I appreciate the suggestions and information.

1968 Camaro NHRA/IHRA SS/C 'Super Stocker' 396/Jerico
1968 Street/Strip Camaro 350 w/PG
1968 Caprice NHRA/IHRA Stock ELiminator O/SA 327-250 HP



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post #12 of 20 (permalink) Old Jan 12th, 13, 08:27 PM Thread Starter
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Re: What cam should I use?

I've received some excellent advice! All of the recommendations seem to basically be the same. It looks like there are minor differences in the lift and durations. I do like the Comp Cam's graph showing the torque and horsepower curves. That would be helpful if all of the brands showed that. Any one of these that have been suggested should work and all of them have positive feedback from those that are using them.

And what I've read elsewhere say if I go with too much cam I won't be happy.

I will buy a kit that includes the springs for the particular cam I buy. The springs that were on it are probably original 1969 equipment.

I've got some time yet before I need to get the cam. Feel free to make any any other comments or suggestions.
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post #13 of 20 (permalink) Old Jan 12th, 13, 08:56 PM
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Re: What cam should I use?

Quote:
Originally Posted by 69ndpce View Post
And what I've read elsewhere say if I go with too much cam I won't be happy.
With 3.08 gears and a stock converter I wouldn't go any bigger than an edelbrock Performer or the Elgin equilivent. 265-400 V8 (1957-86) part number 2102 204 / 214 .420" / .442" 112

http://www.competitionproducts.com/E...uctinfo/E923K/
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post #14 of 20 (permalink) Old Jan 12th, 13, 10:04 PM
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Re: What cam should I use?

Quote:
Originally Posted by 67 Plum View Post
With 3.08 gears and a stock converter I wouldn't go any bigger than an edelbrock Performer or the Elgin equilivent. 265-400 V8 (1957-86) part number 2102 204 / 214 .420" / .442" 112

http://www.competitionproducts.com/E...uctinfo/E923K/
This is great info. With larger cams and high gearing (numerically lower) the car will be less fun to drive than a small-ish cam and the same gearing, I've seen it happen time, and time again. I even did it once and hated life until I could upgrade the drive line.
This is somewhat off topic, but, as far as advertised and .050" duration goes, if the cam had an adv. duration of say 260* advertised and 210* @.050 (the same amount when added) and if a cam has 280* adv and a 214* @.050 what would this indicate? I know it has to do with ramp rates, but which one is more aggressive etc.. I have never fully understood this about cams.

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post #15 of 20 (permalink) Old Jan 13th, 13, 05:06 AM
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Re: What cam should I use?

All this is very true. However, you really need to decide what you want from this engine and do not waver from your plan. Look at these two links:

http://www.compcams.com/Company/CC/c...px?csid=1&sb=2

http://www.northernautoparts.com/Pro...?ProductId=709

The compcams link is showing the specs of the 300 hp 350 CI cam. Notice it was the same cam shaft for a lot of engines? Now look at the base Performer Plus cam in the nothernauto link. Barely over the stock cam specs. Do you want to go to all the trouble of a cam change for that little of a gain? This is what you need to decide and be unwavering about.



Quote:
Originally Posted by ace's68 View Post
This is great info. With larger cams and high gearing (numerically lower) the car will be less fun to drive than a small-ish cam and the same gearing, I've seen it happen time, and time again. I even did it once and hated life until I could upgrade the drive line.
This is somewhat off topic, but, as far as advertised and .050" duration goes, if the cam had an adv. duration of say 260* advertised and 210* @.050 (the same amount when added) and if a cam has 280* adv and a 214* @.050 what would this indicate? I know it has to do with ramp rates, but which one is more aggressive etc.. I have never fully understood this about cams.
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