Cam suggestion for 69 SS350 please - Team Camaro Tech
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post #1 of 43 (permalink) Old Dec 11th, 05, 01:04 PM Thread Starter
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Cam suggestion for 69 SS350 please

I have a 69 SS350 motor that was rebuilt and it seems that it doesn't have as much top end pull as I'd like as the rev's get up, I may have selected the wrong cam and was wondering what you guys think.

Here's what I have:
350 CI, 041 64cc factory heads, 9 to 1 pistons, Comp Cams XE256 (Lift=.440 Intake,.454 Exhaust. Duration @ .050=212 Intake, 218 Exhaust), stock rockers, stock Q-jet on stock intake, stock manifolds, stock distributor, stock exhaust manifolds, M-20 4-speed, 3.55 posi.

I've made sure it's tuned real good and it runs real good but seems to fall flat too soon, maybe around 4500-5000 RPM. I just drive on the street but would like it to pull a little longer and still have good street manners. I think I may have picked too small a cam and was wondering if I should change it, or would some 1.6 rockers help, or maybe this is as good as I should expect?

I'm sure this has been gone over before, but a search didn't really come up with my drivetrain combo.

Thanks Brian

Last edited by BH69Camaro; Dec 11th, 05 at 01:38 PM.
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post #2 of 43 (permalink) Old Dec 11th, 05, 08:44 PM
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Wes
 
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Re: Cam suggestion for 69 SS350 please

That Powermax cam is only good to 5000 according to Crane.

If you want more rpms, a new intake and exhuast (headers) will also help,..as well a as a new cam in the 220-224 duration @ .50.

But what happens at 4500,..does she lay down?...or does she miss?
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post #3 of 43 (permalink) Old Dec 11th, 05, 09:04 PM Thread Starter
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Re: Cam suggestion for 69 SS350 please

I'd like to keep the stock manifolds on it because I like the factory look. At about 4500 it just seems to not pull as hard.
Brian
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post #4 of 43 (permalink) Old Dec 11th, 05, 09:34 PM
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Re: Cam suggestion for 69 SS350 please

You've got a torque cam in a setup that is nowhere near optimized for higher rpm power...I think what your feeling is perfectly normal for your setup. If you are running factory manifolds and a original style exhaust system, that is going to kill your upper rpm power worse than anything as it is not a very good flowing setup. Your intake and carb will support decent power to 5500 rpms or so, assuming things like good fuel pressure, good valve springs, no point bounce, strong ignition coil, etc, etc. IMO, just simply adding a set of 1 5/8" headers and a good 2 1/4" or 2 1/2" dual exhaust system will pick up your 4000 rpm+ power quite dramatically, plus add 500 rpms of useable rev range on the top end. However, I can certainly understand wanting the stock look. If you want to do nothing other than change the cam, I would suggest a comp cams NX262 hydraulic. 262/280, 218/[email protected], 113 lsa. The extra long exhaust timing plus wider lsa is of great benefit with a restrictive exhaust system, plus it has an aggressive intake lobe that will still help it make good power across the board. These NX cams are designed for nitrous applications but they also work well to "crutch" a restrictive exhaust system. IMO, adding 1.6 rockers will not do you any good at this point.

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post #5 of 43 (permalink) Old Dec 11th, 05, 09:37 PM
 
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Re: Cam suggestion for 69 SS350 please

Quote:
Originally Posted by BH69Camaro
I'd like to keep the stock manifolds on it because I like the factory look. At about 4500 it just seems to not pull as hard.
Brian
Do as the factory did and run a factory cam. They ran them with cast iron exhuast and it worked then it should work today. I would go with the Hyd 327/350hp cam PN#3863151 221/221 .447/.447 114 lc. Crane sells this cam as a Muscle Car Cam PN#967601 (I love this cam and use it alot, next favorite is the 1st design Mech Off Road Cam, 257/269 .493/.512 112 lc)

http://www.nastyz28.com/sbchevy/sbccams.html

24502476 Hyd. 212/220 .435"/.460" 9.1:1 112.5 350/300 CC crate motor
14088843 Hyd. 202/206 .403"/.415" 8.5:1 115 '83 to'86 305HO
12364050
3863151 Hyd. 221/221 .447"/.447" 11.0:1 114 327/350HP L-79
12364051
3896929 Hyd. 195/202 .390"/.410" 8.0:1 112 327/300HP
3896962 Hyd. 222/222 .450"/.460" 8.5:1 114 350 L-46, L-82
12353915 Hyd. 194/204 .401"/.423" 8.0:1 104 GM/Crane street
12353914 Hyd. 180/194 .378"/.401" 8.0:1 - GM/Crane very high, low-speed torque
12353923 Hyd. 224/234 .465"/.448" 9.5:1 114 GM/Crane off-road
12353918 Hyd. 214/224 .442"/.465" 8.75:1 112 GM/Crane marine & off-road
12353917 Hyd. 204/214 .420"/.442" 9.0:1 112 GM/Crane non-emissions vehicles & off-road
12353916 Hyd. 204/214 .423"/.446" 8.5:1 110 GM/Crane 50 state legal 305-350
12364052
3849346 Mech. 254/254 .485"/.485" 11.0:1 114 327/365HP & Z-28 302
12364053
3927140 Mech. 257/269 .493"/.512" 12.0:1 112 Off-road
12364054
3972178
3972182 Mech. 242/254 .459"/.485" 11.0:1 116 '70 LT1 360 to 370HP
" " " " 9.0:1 116 71 LT1 330HP
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post #6 of 43 (permalink) Old Dec 12th, 05, 06:02 PM Thread Starter
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Re: Cam suggestion for 69 SS350 please

I guess I'm getting what would be expected out of my setup, and that I could go with a cam with a little more duration and lift. I definitely want to keep the changes internal.

Travis- Do you think I'll feel a good increase with the NX262 cam? I guess what I mean is, if after I change it out, do you think I'll feel it?

Thanks,
Brian
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post #7 of 43 (permalink) Old Dec 13th, 05, 06:17 AM
 
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Smile Re: Cam suggestion for 69 SS350 please

I figure at 9 to 1 CR., a CC 268HE will be a schosh weak down low BUT should do you great!

As for the great old -151 cam, it really needs at least 10 to 1 CR. and preferably 11 like stock. And I ran it as a daily driver for years after 1,200 mile's new in my car back in the spring of '67!

I will say it's charge from about 3,000 rpm in second up to the top end of third is AWESOME!!! I used to motor by cars that would get me like 2 cars out of the hole!!

pdq67



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post #8 of 43 (permalink) Old Dec 14th, 05, 12:29 AM
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Re: Cam suggestion for 69 SS350 please

Quote:
Originally Posted by BH69Camaro
I guess I'm getting what would be expected out of my setup, and that I could go with a cam with a little more duration and lift. I definitely want to keep the changes internal.

Travis- Do you think I'll feel a good increase with the NX262 cam? I guess what I mean is, if after I change it out, do you think I'll feel it?

Thanks,
Brian
I'll run some dyno sims when I get home, and post the results.

"This is not a cheerocracy...I make the cheercisions around here"
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post #9 of 43 (permalink) Old Dec 14th, 05, 07:17 AM
 
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Re: Cam suggestion for 69 SS350 please

BH69Camaro,

I understood from your original post that you have stock intake/exhaust manifolds, and you want to keep them. What is the rest of your exhaust system setup?

You may already have this but, if you don't, you would make some gains by going to a free flowing 2.5" dual exhaust setup.

-Mark
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post #10 of 43 (permalink) Old Dec 14th, 05, 08:04 AM
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Re: Cam suggestion for 69 SS350 please

Why not port out the exhaust and intake maifolds as big as you can, install a nice free flow 2 1/2" dual exhaust, and get the upgraded cam.. My engine builder swears by Isky hydrulics, maybe a 272. You could also bump up the comp alittle closer to 10:1.... I would also invest in a good set of valve springs....
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post #11 of 43 (permalink) Old Dec 14th, 05, 02:35 PM Thread Starter
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Thumbs up Re: Cam suggestion for 69 SS350 please

Quote:
Originally Posted by travis
I'll run some dyno sims when I get home, and post the results.
Travis-Very cool, Thanks!!!

Mark- My exhaust is the 2 1/4" factory system from Rick's, it's mandrel bent though and I love the sound.

Robo- Thanks for the suggestions, those would be good things to do while swapping out the cam.

Brian
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post #12 of 43 (permalink) Old Dec 14th, 05, 06:23 PM
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Re: Cam suggestion for 69 SS350 please

Ok...here goes...

As I suspected, and your seat of the pants dyno observed, with your current setup power peaks at about 4500rpms, at 280hp. 330 ft-lbs at 3500 peak, with a strong torque curve but power falls off a cliff by just after 5K. I made some assumptions here...log type manifolds, and 600cfm exhaust flow. I assume this engine is 9-1 compression because you put dished pistons in it? In any case, this would be a nice daily driver package. Pretty much any cam I tried hurts midrange torque (some worse than others) with minimal top end power gains. A few of cams I ran thru came out with interesting results though. The crane 278 powermax (222/[email protected], .467/.494, 114lsa, 109 ica) hurts the least on the low end with a nice power increase at 4500, and peaks at 5000 rpms with considerably less drop off up to 5500 rpms. Increasing the compression to 10:1 makes that cam work even better, peaking at [email protected] rpms, with minimal low end torque loss. GM's -151 350hp 327 hydraulic also makes a good showing, but it too needs 10-1 compression to really sing (and keep the midrange torque up). The best cam I tried was the -178 GM solid (LT-1 cam). With 10:1 compression, it makes over 50hp more at peak than you current setup, pulling well to nearly 6K. I don't know if I believe the low end torque numbers, but if they are close to true, it would pull similar to your current setup with much greater top end power. And, the 278 crane, -151, and -178 have nearly identical cranking compression numbers as what you have now...meaning that whatever fuel you are running now you could still run with 10:1 compression and one of these cams.
I also took the liberty of running your current setup as is, only adding a set of 1 5/8" x 34" headers. It spanks the other combo's up to 5K, with considerably less dropoff past 5K.
According to the program, to get your power to peak up around 5200 rpms with a 110 lsa hydraulic cam, you would need a cam of about [email protected], but any cam in that size range with your current setup just kills your power curve under 4K.

As is, with your setup, the best power curve I found was with a small crower solid flat tappet cam. I don't have a catalog handy to give you a part number, but its specs are 230/[email protected], .456/.458 lift, 112 lsa...its listed as a "pro street" solid. That cam, per the sim, gives just a minute amount of torque loss at 2000 rpms, and then takes off from there, peaking at 5K, with minimal drop off after that. If you have the 981-16 comp cams springs, the crower solid should work well with them. If your not opposed to a solid, then this appears to be the cam for you.

This is just a sim program, but the numbers are believable.

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post #13 of 43 (permalink) Old Dec 14th, 05, 10:18 PM Thread Starter
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Re: Cam suggestion for 69 SS350 please

Travis- Wow, that's a lot of good information. The assumptions you made on the log manifolds are correct. I really do want to keep my current setup so it looks like if I really want to feel a lot more power, I'd have to change my pistons to 10 to 1 along with a new cam.

I don't know if the pistons are dished or not, I had the engine built and I chose the compression ratio and cam based on reading a bunch of magazine articles for a good driver, which it really is...but I just wish it pulled a little longer when I get on it.

I've got to think about what I want to do now, and it's really good to know the information you came up with, I'll be reading it over and over. That'll really help me get the fruits of the labor...Thanks Bud!!

Brian
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post #14 of 43 (permalink) Old Dec 15th, 05, 05:18 AM
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Re: Cam suggestion for 69 SS350 please

Quote:
Originally Posted by BH69Camaro
I have a 69 SS350 motor that was rebuilt and it seems that it doesn't have as much top end pull as I'd like as the rev's get up, I may have selected the wrong cam and was wondering what you guys think.

Here's what I have:
350 CI, 041 64cc factory heads, 9 to 1 pistons, Comp Cams XE256 (Lift=.440 Intake,.454 Exhaust. Duration @ .050=212 Intake, 218 Exhaust), stock rockers, stock Q-jet on stock intake, stock manifolds, stock distributor, stock exhaust manifolds, M-20 4-speed, 3.55 posi.

I've made sure it's tuned real good and it runs real good but seems to fall flat too soon, maybe around 4500-5000 RPM. I just drive on the street but would like it to pull a little longer and still have good street manners. I think I may have picked too small a cam and was wondering if I should change it, or would some 1.6 rockers help, or maybe this is as good as I should expect?

I'm sure this has been gone over before, but a search didn't really come up with my drivetrain combo.

Thanks Brian
You don't say if you have power brakes or not, but even if you do put in the factory G.M. (#3896692) L-82 cam, it'll wake that unit up big time. What you have for a cam now we install in units that we chase "gas-mileage" only. A setup on the dyno recently similar to your's, but with larger valves, made almost 360 HP and 400 Ft.Lbs. torque through the Q-jet and stock cast exhaust manifolds. If I remember correctly however it did have 9.7:1 C.R. You could get your's up some by a little milling. Thanks, Gary in N.Y.
P.S. The cam specs are 224* x 224* @ .050", x .450" x .460 x 114 L/S, and if you throw a set of 1.6's on the intakes only, you'll be at .480" lift on the
intakes. As I said, it'll bring that unit to "life". It should "see" some decent vacuum numbers. Trans & rear should be right on the money. The larger valves here will have no no advantage on the power under 5000 RPM. Some "bowl" work would be a plus however, even with the 1.940's and stock exhaust manifolds. If you do have power brakes don't change the lobe separation. If you don't then you can narrow that down slightly (108*) due to having a "stick" car.

Last edited by GOSFAST; Dec 15th, 05 at 05:28 AM. Reason: Add Info
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post #15 of 43 (permalink) Old Dec 15th, 05, 09:15 AM
 
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Smile Re: Cam suggestion for 69 SS350 please

At 9 to 1 CR, I bet an Isky Z-20 solid cam will do you nicely!!

BUT I would bowl blend the valves and do some casting flash/dingle-berry port clean up which along with a set of cheap four tube, long headers AND a pair of high flowing mufflers should get you up to about 340 hp at 5,000 rpm and right at 400 to from 35 to 4,000 rpm. (Per D2K..)...

You will have a heck of a flat torque curve which will make for a great street motor, imho...

I would however find out just what the CR. really is as well as the head chamber cc's and how thick a headgasket you have??

I mention this b/c like everybody is saying IF you can get her up to right under 10 to 1 By changing heads and using a Fel-pro #1094, .015" thick shim headgasket you will make more power b/c then you can run a bigger cam AND still use pump gas!!

As always, imho...

pdq67



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