Cam question - Team Camaro Tech
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post #1 of 13 (permalink) Old Jul 19th, 14, 04:38 PM Thread Starter
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Tony
 
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Cam question

What is a good cam for a L48 currently all stock. It was bored either .20 over with stock compression pistons and nothing extra done to the heads before I owned it. The carb is a Rochester (not sure if that matters). It has stock exhaust manifolds and cast iron intake too.
I want to keep the appearance the same but was chewing on changing the cam to open it up more than stock to improve performance without going too crazy.
After some gear advice I am changing the gears from 3.08 limited to 3.42 posi.

Any advice on a cam or any other suggestions to improve performance without affecting the stock look?

1969 Camaro SS350, original motor/12 bolt/interior and build sheet in Fathom Green.
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post #2 of 13 (permalink) Old Jul 20th, 14, 10:36 AM
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Brian
 
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Re: Cam question

Stock compression on that motor is 10:25:1? That's pretty beastly... You could add more intake duration beyond the 200 you have but with that you need to get that fuel mix to fill the cylinders efficiently. Without changes to lift or valve sizes it might be a flop going a lot more duration, so mild improvements are best. Btw I'd keep that engine stock also!

1969 Camaro 383
2.02/1.63 & 234/244 Vortec
TH350 / 12 bolt 3.73
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post #3 of 13 (permalink) Old Jul 20th, 14, 12:23 PM
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Anne
 
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Re: Cam question

Quote:
Originally Posted by TClovis View Post
.
After some gear advice I am changing the gears from 3.08 limited to 3.42 posi.

Any advice on a cam or any other suggestions to improve performance without affecting the stock look?
A mild hydraulic roller will wake it up. Something like this will add ~ 30 hp :

http://www.summitracing.com/parts/cc...make/chevrolet

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post #4 of 13 (permalink) Old Jul 20th, 14, 03:09 PM
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Brian
 
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Re: Cam question

Going to a roller cam is a lot of head and block work and not a simple upgrade.

1969 Camaro 383
2.02/1.63 & 234/244 Vortec
TH350 / 12 bolt 3.73
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post #5 of 13 (permalink) Old Jul 20th, 14, 03:41 PM
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Doug
 
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Re: Cam question

The retro-fit hyd. rollers are not any harder to change than any other camshaft. You would have to check (mic) the camshaft bearings and the lifter bores. This is something that should be done on any rebuild. This would be a good camshaft to for a 350 ci engine. http://www.summitracing.com/parts/hr...make/chevrolet But unless you were going to change to an Edelbrock Performer RPM aluminum intake and a set of long tube headers it would be a waste of time and money.
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post #6 of 13 (permalink) Old Jul 20th, 14, 04:38 PM
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Re: Cam question

I run the Crane 274H06 Energizer Hydraulic Flat Tappet. Duration 274/274, Lift .450/.450. I have a 68 350/295 with stock exhaust manifolds and 2.5 duals. The only other engine mod, if you can call it that, is the Protronix ignition module (points replacement). Stock quadrajet carb and did not have to change any jetting.

This cam while not wild and crazy, added a good bit of low and mid zip to this engine. I have a 4 speed but I am certain you could get by with an automatic without a stall converter.

It's not the most wicked sounding cam but then, I wasn't really going for that. I car club buddy has the same engine as I do and he installed a Thumpr cam. It sounds all nasty but I am not so sure it added any power.

This you tube is my car so you can at least hear the way it idles.

https://www.youtube.com/watch?v=6DTVLbNsq4E

Prepare to be the center of attention when you drive a first generation Camaro. You will be gawked at. Grown men & women will coo like children when you drive past. Children will scream like babies. Dogs & cats will get along. Does it get any better?
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post #7 of 13 (permalink) Old Jul 20th, 14, 06:25 PM
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Chet
 
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Re: Cam question

Ridiculous. How can anybody recommend a cam with the information that "he just wants to wake it up? What stall? What rear gear? Define "woken up". That's a 300 hp 350. 10.25:1 compression was more like 9.8:1. How old are the springs in the heads?

You have $800 its real easy to convert non-roller block to roller cam. That's the cost of the retro-fit rollers that drop right in and the cam itself. Still need a thrust button to keep cam from walking, possibly new distributor gear.

You want to wake up that car, quickly and inexpensively? Put a pair of good headers on it with a true dual exhaust. You will be amazed at the difference. Then if you want more, look at a rear gear change. Want more still, think about a set of modern heads on it with a cam that matches the flow numbers of those heads and fits how you want to drive the car.
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post #8 of 13 (permalink) Old Jul 20th, 14, 09:21 PM
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Re: Cam question

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Originally Posted by onefiness View Post
That's a 300 hp 350. 10.25:1 compression was more like 9.8:1. How old are the springs in the heads?
L65 was a 9:1, L48 had the 300 HP and 10.25:1. It was basically a stroked 327 as I understand it.

Personally I don't view cam choices in isolation of the other two major factors in filling cylinders--- valve lift and valve size. This engine has a short valve lift.

1969 Camaro 383
2.02/1.63 & 234/244 Vortec
TH350 / 12 bolt 3.73
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post #9 of 13 (permalink) Old Jul 21st, 14, 01:19 PM
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Re: Cam question

I have the basically the same set up in a 68 SS350 except it is a 4 speed. I used the old 327/350HP cam. Rumbles a bit and runs great. You won't need screw in studs either.

Bob
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post #10 of 13 (permalink) Old Jul 21st, 14, 02:05 PM
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Tom
 
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Re: Cam question

I am presently running a Crane 272H10 in my 327. This is a mild single pattern cam with good street manners and would be good in an otherwise stock 350. The valve lift is .450" and the duration is 216 degrees. It has more of a burble-burble sound than a potato-potato sound.

Gas mileage on the highway is ~18 mpg. Has gone to a best of 20 mpg with a Qjet carb. It is installed 2 degrees advanced(plus the 5 degrees ground in, iirc). You would notice an increase in torque over the stocker with no downside. Vac is 15-16" and idles at 700rpm or lower. I like it at 850 because of the stick(and my RS hood release resonates like crazy at lower idles )

All that said, this is just one option from Crane and there are plenty of others from the other manufacturers. I can only vouch for what I personally have tried. Previously ran the Edelbrock Performer cam which is also widely used as a "one step above stock" cam and I would not use it again. The 272h10 is way better with no tradeoff.

I would also consider the Crane 274H06 mentioned above which would have more punchy low-midrange and a "potato-potato" sounding idle(see Craig's video above-sounds great!!!). I have one of these on the shelf that I will probably swap in soon. It has about the same lift and duration but with a tighter lobe separation that accounts for the performance and sound difference while still being easy on the valvetrain.

'67 rs - ordered new by my Grandfather
327 L30, K-K, Deluxe int, tach & gauges, 12 bolt posi, 4 speed.

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post #11 of 13 (permalink) Old Jul 21st, 14, 02:28 PM
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Lynn
 
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Re: Cam question

Hydraulic: use a copy of the 69 L46 camshaft. Almost the same specs as the 327-350 horse hydraulic cam noted above. No other changes needed.

If you are up for solid lifters, use a copy of the 70 LT-1 camshaft. Federal Mogul makes a cam and lifter kit that is available through Rock Auto. If you do that, I would pull the heads, and install a thinner head gasket to raise compression slightly. With the extra duration (and tighter quench) you can get away with 10.5 or even 10.75 easily. You can re-use your manifold and Qjet (virtually the same as used on the L46 and it was rated at 350 hp), or go with an aluminum hi rise.

With either of the above you can keep your stock springs. Just don't wind it above 6500 regularly. But then, really no need for more with either of the above combos as the torque curve is pretty broad.

I also would not go to the trouble of hogging out the intakes for 2.02 valves on a street car. I know you didn't ask about head changes, just trying to anticipate the next question.

Lynn
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post #12 of 13 (permalink) Old Jul 21st, 14, 02:35 PM
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Re: Cam question

Quote:
Originally Posted by bilodeaulynn View Post
Hydraulic: use a copy of the 69 L46 camshaft. Almost the same specs as the 327-350 horse hydraulic cam noted above. No other changes needed.

If you are up for solid lifters, use a copy of the 70 LT-1 camshaft. Federal Mogul makes a cam and lifter kit that is available through Rock Auto. If you do that, I would pull the heads, and install a thinner head gasket to raise compression slightly. With the extra duration (and tighter quench) you can get away with 10.5 or even 10.75 easily. You can re-use your manifold and Qjet (virtually the same as used on the L46 and it was rated at 350 hp), or go with an aluminum hi rise.

With either of the above you can keep your stock springs. Just don't wind it above 6500 regularly. But then, really no need for more with either of the above combos as the torque curve is pretty broad.

I also would not go to the trouble of hogging out the intakes for 2.02 valves on a street car. I know you didn't ask about head changes, just trying to anticipate the next question.

There we go Lynn, thank you very much- I knew someone would understand this set up more. I was thinking ya have to use caution with over-lifting on this engine and the compression. Could turn into a lot of money altering other things to avoid colliding a piston with a valve.

1969 Camaro 383
2.02/1.63 & 234/244 Vortec
TH350 / 12 bolt 3.73
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post #13 of 13 (permalink) Old Jul 23rd, 14, 05:13 AM
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Re: Cam question

Quote:
Originally Posted by Cdminter55 View Post
But unless you were going to change to an Edelbrock Performer RPM aluminum intake and a set of long tube headers it would be a waste of time and money.
X2

You "might" pick up a little more power with the "correct" aftermarket cam swap, but IMO, it wouldn't be enough to warrant the effort and cost in the change without installing a good induction system along with headers and good free flowing dual exhaust.

Darren
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